KNES 260: MIDTERM STUDY GUIDE
ANATOMY: MEDIASTINUM & HEART & CARDIOVASCULAR CIRCULATIONArteries :
• Walls of arteries have three layers
I. Tunica Adventitia (outer layer)
II. Tunica Media (middle smooth muscle layer)
This layer maintains the artery’s round shape
Elastic lamina helps maintain the shape of the artery along with the Tunica Media
III. Tunica Intima (inner layer)
There is a smooth inner lumen
• Carries blood from heart to tissue
→ Carries blood away from the heart!
• Decreasing size of vessels goes from arteries à arterioles à capillaries
→ All three sizes of vessels all have smooth muscle
• There are three types of arteries:
I. Elastic
→ Are largest in size
→ Allow for high degree of expansion between heart beats
→ Example: thoracic and abdominal aorta
II. Muscular
→ Distributing arteries
→ It regulates blood flow to different parts of the body
→ Example: femoral arteries
III. Arterioles
→ Has a narrow lumina (narrow opening)
→ Thick muscular walls
→ Blood pressure is regulated by degree of muscular tone
→ Examples: tributaries
Veins:
• Veins carry blood from tissue to heart
I. Veins return blood to heart!
• Increasing size of vessels go from capillaries à venulesà veins
• Three types of veins:
I. Large (Inferior Vena Cava)
Have wide bundles of smooth muscles
Welldeveloped Tunica Adventitia (outer layer)
II. Medium (Great Saphenous Vein)
Contains vessels that maintain blood flow in the right direction
Muscles must contract in order to pump blood into the next compartment (musculovenous pump)
III. Small (Venules)
Unite to form the venous plexuses
Doesn’t contain noticeable amounts of smooth muscle (thus the shape isn’t like the shape of an artery)
• Structure of the vein is similar to the structure of arteries however:
→ Walls are thinner due to a lower blood pressure
→ There is a poorly developed muscular layer
→ There are accompanying (communicating) vein for extremity arteries
→ Larger of the valves have valves in them
Capillaries:
• Simple endothelial tubes
• Do not have tunica layers
• These vessels have the diameter of a red blood cell
• Are arranged in networks called capillary beds
• Nutrients and other materials are exchanged through diffusion (example: O2, CO2)
Mediastinum: (I need a better explanation for this, I am totally lost… not exactly sure where it is?)
• It is the middle space
• Middle septum occupied by tissue between two pulmonary cavities
• Covered on each side by the mediastinal pleura
• Tissues untied by loose connective tissue and infiltrated by fat (it separates the heart and lungs)
• Allows for accommodation to changes in movement, volume, and pressure
Heart:
• Pericardium: a doublewalled fiberous sac enclosing the heart
o Outer Fiberous Pericardium: it stabilizing and prevents overdilation
o Serous Pericardium: it lies within and directly covers the heart
Visceral Layer
Partial Layer
o Pericardial cavity is a space filled with fluid that allows the heart to beat in a frictionless environment
• There is a double selfadjusting muscular pump
• Right side of heart receives and sends deoxygenated blood
• Left side of heart receives and sends oxygenated blood
• Three tissue layers of the heart:
o Endocardium: internal layer of protection
o Myocardium: thick middle layer for contraction (the heart is mainly comprised of this layer)
o Epicardium: thin external layer for lubrication
• Summary of the layers from most external to most internal:
→ Pericardium: a fiberous sac enclosing the heart
→ Epicardium: outermost tissue layer of the heart that provides lubrication
→ Myocardium: middle tissue layer of the heart, it is the thickest and it is for contraction
→ Endocardium: innermost layer of the heart, provides protection
• when ventricles contract, they produce a wringing (squeezing, twisting) motion due to spiral orientation of cardiac muscle
→ this propels blood out
→ the muscle fibers are anchored to fibrous skeleton of dense collagen
the fibrous skeleton prevents:
• over dilation
• provides attachment
• forms and electrical insulator
Cardiac Cycle:
• Deoxygenated blood enters through the right atrium and exits through right ventricle into the lung, oxygenated blood enters through the left atrium and through the right ventricle and exits into the ascending aorta.
• Period of relaxation (diastole): is relaxation of the ventricles and filling of atria (“lub” sound)
• Period of contraction (systole): is period of contraction of the ventricles (“dub” sound)
• Sounds are produced by the snapping shut of one way valves
Atrium:
• Smooth thinwalled interior
• Musculi pectinati (small ridges of muscle) for contraction and movement of blood to ventricles
• Atria don’t require a lot of muscle, they require a lot of room.
• Interatrial septum between atria (it’s a wall that separates the two atria)
o Fossa ovalis (foramen ovale)
The foramen ovale is an opening between the two atria that closes up after birth and forms the fossa ovalis.
Ventricles:
• Muscular elevation are called trabeculae carnae
o They produce vigorous contraction
• Tendinous (sinewy) cords extend from the papillary muscles to the chordae tendinae
o Chordae Tendinae prevents blood from backflowing through the one way valve
• Interventricular septum separates the two ventricles
Cardiovascular Circulation:
• Deoxygenated Blood:
o Deoxygenated blood from the Superior Vena Cava, Inferior Vena Cava, and Coronary Sinus dump into the right atrium
o The blood travels through the tricuspid valve into the right ventricle
o Blood then goes through the pulmonary semilunar valve into the pulmonary trunk
o The pulmonary trunk bifurcates into the right and left pulmonary arteries which then travel to each lung
• Oxygenated Blood:
o Oxygenated blood from the pulmonary veins enter the left atrium
o It travels through the bicuspid valve to the left ventricle
o From the left ventricle, blood travels through the aortic semilunar valve and up to the ascending aorta where blood then enters general circulation
Heart will first take blood via coronary artery before it enters the ascending aorta
• Diagram:
Deoxygenated blood from Superior Vena Cava, Inferior Vena Cava, Coronary Sinus à Right Atrium à Tricuspid Valve à Right Ventricle à Pulmonary SemiLunar Valve à Pulmonary Trunk à Pulmonary Arteries à Lungs à Pulmonary Veins à Left Atrium à Bicuspid Valve à Left Ventricle à Aortic Semi Lunar Valve à Ascending Aorta à General Circulation
Values:
• Valves serve to prevent back flow of blood through one way valves
• They are held in place by fiberous connective tissue
Venous Return: (What exactly is systemic circulation… it’s a dumb question, I know…)
• All systemic circulation dumps into the right atrium
• Cardiac circulation is attached to systemic circulation
o Systemic system is when blood is transported from the heart to other parts of the body and back
• Veins drain into coronary sinus, which dumps into the right atrium (so, let me get this straight: all blood from the SVC and IVC all go into the coronary sinus, which then goes into the right atrium?)
Bypass Surgery:
• Uses either the great saphenous vein or the internal thoracic artery to replace
• Bypass = when coronary arteries are blocked
• Double bypass = when two coronary arteries are blocked
SUMMARY:
ANATOMY: THORACIC AND ABDOMINAL CIRCULATION: • Brain must have 8% of blood supply at all times
• Entire digestion system goes to liver, kidney doesn’t have anything to do with it
Costal Groove:
• Contains intercostal artery, vein, and nerve neurovascular bundle
• Runs on the posterior aspect of each rib
• Most of the red blood cells are made by the ribs
• Intercostals help with inhalation and exhalation
Arteries of the Thorax:
• Thoracic aorta
• Axillary artery
• Subclavian artery
Azygos Venous System:
• Venous return via the intercostal vein
• Most posterior intercostal vein dumps into the Azygos system (when you say most posterior, are you saying the MOST posterior as in there are anterior intercostal veins and other parts of the posterior vein, or is it that MOST OF THE posterior intercostal vein dumps into the Azygos system?)
• Azygos venous system is a pathway between the Superior Vena Cava and the Inferior Vena Cava in an effort to not overdilate the heart
• Azygos vein = drains right side of posterior thorax
• Hemiazygos vein = drains left lower posterior thorax
• Accessory hemiazygos = drains left upper posterior thorax
Circulation to the Abdomen:
• Abdominal aorta
→ From thoracic descending aorta
→ Passes through aortic hiatus of diaphragm
→ Branches of the Abdominal Aorta:
• Celiac trunk
Distal to aortic hiatus
I. Splenic artery
Supplies blood to the spleen, pancreas, and greater curvature of the stomach
The artery is curly to lengthen the route to the spleen because the spleen cannot handle the pressure
I. Common hepatic artery
• Supplies liver, gallbladder, stomach, pancreas, and duodenum
• Supplies the liver!
Gastroduodenal
• Supplies blood to the stomach, pancreas, and proximal duodenum
II. Left gastric artery
Supplies distal esophagus and lesser curve of the stomach
• Superior mesenteric artery
→ Supplies blood to part of the gastrointestinal (GI) tract
• Renal arteries
→ Supplies blood to kidneys
• Inferior mesenteric
→ Supplies the lower part of the GI tract
→ Iliac arteries
• It is the bifurcation of the abdominal aorta
Venous Return:
• Four important veins:
→ Superior Mesenteric
→ Splenic
→ Inferior Mesenteric
→ Portal
Fetal Circulation: (SO LOST)
• All embryotic nutritional needs are provided by diffusion across the placenta
o Fetal hemoglobin has a higher attraction for O2 and thus, allows diffusion of O2 from mother to fetus
• Umbilical arteries bring deoxygenated blood to placenta from internal iliac arteries
o Deoxygenated blood from fetus to placenta
• Blood returned oxygenated via umbilical vein
o Umbilical vein: brings blood from placenta to the fetus
• Placenta acts as a liver and a lung
• Difference in fetal and infant circulation:
o Blood returning via umbilical veins bypass liver to inferior vena cava
o Since pressure in right atrium exceeds that of the left atrium, foramen ovale allows blood to bypass right ventricle
o Ductus ateriosus takes blood from right ventricle to the aorta
• Clamping of the umbilical cord:
o Umbilical veins become ligamentum teres
o Umbilical arteries to become ligaments
o With first breath:
Ductus Ateriosus constricts and becomes ligamentum arteriosum
• Ductus arteriosus = blood from right ventricle goes to the aorta (only open in utero)
Ductus venosus contricts and becomes ligamentum venosum
Increased pressure in left atrium and decreased right atrium pressure causes foramen ovale to close and become fossa ovalis
SUMMARY:
ANATOMY: PERIPHERAL CIRCULATIONArteries:
• Aortic arch:
o Brachiocephalic trunk
Right subclavian
Right common carotid
o Left common carotid
o Left subclavian
• Arteries in the arm:
o Subclavian artery
o Axillary artery
o Brachial artery
Ulnar
Radial
• Arteries going into the neck:
o Common carotid
Internal carotid – brain
External carotid – face and scalp
• Arteries in the leg:
o Common iliac
Internal – stays in the pelvic basin
External
• Femoral artery
• Popliteal artery
o Posterior tibial
o Anterior tibial
o Peroneal
Veins:
• Veins in the arms:
o Subclavian
o Axillary
o Basilic
o Cephalic
o Median cubital
o Median antebrachial?
• Veins in the legs:
o Blood in legs must return to femoral vein
o Greater saphenous
o Lesser saphenous
o If the lesser saphenous vein is blocked, can blood still return to the femoral artery?
Yes, because the greater saphenous vein
SUMMARY:
CARDIOVASCULAR PHYSIOLOGY: HEART: Anatomy of the Circulatory System:
• Pulmonary system – heart to the lung
o It has a low pressure circuit
o Left ventricle pumps more
• Systemic system heart to everywhere else on the body
o There is a very strong pump
• Heart anatomy:
o Left ventricle is a lot thicker than the right ventricle because it has to pump more blood
Heart Muscle and Electrical Excitation:
• Cardiac muscle:
o Is striated (has A bands, I bands, M lines, Z lines, etcetera)
o Has a TTubule system
o Has troponin (calcium activated and removes tropomyosin from myosin)
o Must have calcium ions activate troponin to achieve cross bridge cycle
o Cells are connected by gap junctions (molecular tunnels that allow for faster electrical conduction) and desmosomes (holds the cardiac cells together) at the intercalated discs
• Electrical Excitation:
o Sinoatrial node (SA Node)
It is found at the function between the Superior Vena Cava and the right atrium
Primary pacemaker
Primary pacemaker because it undergoes spontaneous depolarization fastest
It is muscle not nerve tissue
Impulses of the SA nodes are conducted through the atria rapidly due to the gap junctions and the wave of excitation causes the atrial cells to contract
SA node is autorhythmic
o Atrialventricular node (AV Node)
Found at the junction of the right atrium and right ventricle
Secondary pacemaker
It is muscle not nerve tissue
The pacemaker potential also occurs in the AV node, however because it is much slower, the SA node is the primary pace maker
AV node is also autorhythmic
Main job of the AV node is to allow atria to contract and then the ventricles to contract, this is very important!
• It receives the wave of excitation from the SA node but then it delays the signal to the ventricles by 100ms. (the AV Nodal Delay)
o Pacemaker Potential: The slow rise in membrane potential (depolarization) prior to an action potential in the SA node.
Summary of the Pacemaker Potential:
→ K+ ion channel closes
→ N+ ion channel opens and Na+ ion rush into cell
→ Ttype calcium channels open and the membrane potential rushes towards threshold
o Ttype calcium channels are transient and close quickly
→ Threshold is passed
→ Ttype calcium channels close and Ltype calcium channels open
o Ltype are long lasting calcium channels
→ Causes depolarization and an action potential
→ Ltype channels closes and K+ channels open and K+ ions rush out, causing the SA node cells to return to normal and become repolarized again
→ Series of events repeats itself and thus, the SA node is autorhythmic
→ The waves of excitation travel rapidly down the left and right branches of the Bundle of His and the Purkinje Fiber System
Changes membrane potential away from threshold to threshold that occurs prior action potential
Steeper pacemaker potential = heart beats faster
Shallower pacemaker potential = heart beasts slower
Heart Muscle Electrical Excitation
2
3
1
Memberane Potential (mV)
Pacemaker Potential
Time (ms)
1.Pacemaker Potential:
• K+ channels close
• Na+ continues to leak inwards
• Ttype calcium channels open around – 55 to – 50 mV
• Calcium leaks into cell
• These channels are transient (which means they don’t stay open for long)
2. Threshold is reached:
• Ltype calcium channels open
→ These are long lasting calcium channels
• This causes rapid depolarization and an action potential
3.Repolarization:
• Ltype calcium channels close
• K+ (rectifier/correcter) channel opens and allows K+ ions to leave cells of the SA node, thus repolarizing it
o Ventricular Muscle Action Potential:
Events:
→ There is no pacemaker potential
→ Period of depolarization is much longer
→ Action potential is 200 – 300 ms in length
Stage 1:
→ At rest, membrane potential is – 90 mV
→ It is permeable to K+ ions
→ Impermeable to Ca++ and Na+ ions
→ A wave of excitation causes the membrane to become permeable to Na+ ions and K+ channels to close
→ Membrane potential rises to about 30 mV
Stage 2:
→ Na+ inactivation
→ Opening of Ltype Ca++ channels which an influx of Ca++ ions occurs
→ This prolongs depolarization and thus, a plateau occurs
Stage 3:
→ Ltype ion channels close and K+ channels open
→ K+ efflux which causes repolarization
o Myocardial Muscle Contraction: look this over!
20% of calcium comes from extracellular fluid
Calcium from extracellular fluid stimulates release of calcium from sarcoplasmic reticulum
Steps to Myocardial Muscle Contraction:
→ Current spreads from one contractile (autorhythmic cell) cell to another through gap junctions
→ Action potential travels down plasma membrane and TTubules
→ Ca2+ channels open in plasma membrane and sarcoplasmic reticulum
→ Ca2+ that comes from the extracellular fluid induces sarcoplasmic reticulum to release Ca2+
→ Cross bridge cycle begins
→ Ca2+ is actively being transported back to the extracellular fluid and sarcoplasmic reticulum
→ Tropomyosin block myosin binding sites and the muscle fiber relaxes
ECG : Electrocardiogram
R
P 1 2 T 3
S
• P wave = caused by atrial depolarization that is initiated by the SA node
• 1 = plateau caused by the impulse delayed at the AV node
• Q & R & S wave = ventricular depolarization that begins at the apex and atrial repolarization occurs
• 2 = ventricular depolarization is complete
• T wave = Ventricular repolarization that begins at the apex
• 3 = ventricular repolarization is complete
Cardiac Cycle:
• Wigger’s Diagram
• Steps to the Cardiac Cycle:
1. Blood returns to the atria (both atria) and fill it. The pressure against the atrioventricular valves force the valves upon
2. Ventricles fill with blood and as they fill, the flaps of the atrioventricular valves (tricuspid and bicuspid) hang open in the ventricles.
3. Atria contract and force more blood into the ventricles.
4. Ventricles contract.
5. The blood pushes against the atrioventricular valves forcing them close
6. The papillary muscles contract and the chordae tendinae tighten and prevent the valve flaps from opening.
7. The pressure from the ventricles contracting forces the semilunar valves to open.
8. As the ventricles relax, blood flows back down the artery and it fills the cusps of the semilunar valves, thus, closing them.
→ THIS IS FOR THE LEFT SIDE OF THE HEART, right side would be different
→ Pressure:
• Green line: pressure in the aorta
o Greater amount of pressure in the aorta as the ventricle is contracting and pushing blood into the aorta
o The dicrotic notch occurs because the aorta is very elastic and it bulges outward before rebounding
• Blue line: left ventricle
o Great pressure in the left ventricle as it is contracting and pushing blood
• Purple line: Atrial systole
→ Ventricular Volume: black line
• Increases as atrium fills and atrioventricular valves open and increases even more as atria contract. Then decreases as ventricles contract.
Autonomic Control of Cardiac Output:
• Cardiac output: the amount of blood ejected from the left or right ventricle per minute
• Cardiac output = stroke volume X heart rate
o CO = SV x HR
• Autonomic control of the heart – parasympathetic and sympathetic control of the heart
o Parasympathetic (resting) Input: the Sa and Av nodes are controlled by the input from the parasympathetic nervous system via the Vagus nerve
o Action:
→ Cholmergic muscarinic receptors (metabotropic) – stimulates Gprotein
→ Inhibits cAMP
→ Increases K+ efflux
→ Decreases Na+ influx during pacemaker potential
→ Decreases heart rate
o Sympathetic Control:
→ Effects the SA and Av nodes, and Bundle of His / Purkinje
→ SA Node:
• Norepinephrine acts on beta adrenergic receptors à increase in cAMP production (via action Gproteins)
• Decreases K+ efflux
• Increases Na+ influx
• Thus, increases heart rate
→ AV Node:
• Reduces AV nodal delay
→ Bundle of His / Purkinje Fibers:
• Faster conduction
o Sympathetic effect of myocardium:
→ Norepinephrine and epinephrine act on beta 1 adrenergic receptors à activates acetylate cyclase à which increases cAMP à opens more Ltype calcium channels
• Increases the force of the contractions
• Increases stroke volume
FrankStarling Law of the Heart: (Bloody confused)
• Intrinsic control of strength of myocardial contraction
→ Skeletal muscle has an optimal length tension where the maximum tension is produced
→ Cardiac muscle doesn’t have optical position of actin and myosin at rest
This allows filling of blood during exercise and excitement
The greater the end diastole volume the greater the stroke volume
The greater the preload (the amount of filling) the greater the stretch of the myocardium and then the greater the force of contraction.
→ What affects stroke volume?
Venous return (more blood = more stroke volume)
Parasympathetic – changes heart rate
Sympathetic nervous system – changes rate of contraction
Heart Metabolism:
• Heart muscles are highly oxidative
o It has an abundance of mitochondria and myoglobin
o Its main energy sores is fatty acids
o Relies on coronary circulation
Coronary Circulation:
• Most of the coronary blood flow take place during diastole
VASCULATURE: Circulation:
• Blood is mainly kept in the venous return during rest
• Capillary endothelium:
o Endothelial cells can prevent blood flow
Not all endothelial cells are created equal
Some are more ‘leaky’ than others
• Types of vessels:
→ Artery – muscular and highly elastic
→ Arterioles – muscular and well innervated
→ Capillaries – thin walled and highly permeable
→ Venules – thin walled and contains smooth muscle
→ Veins – thin walled, fairly muscular, highly distensible (expandable)
Hemodynamics:
• The flow of blood is through the vessels (F) is dependent on the pressure gradient along the vessel (DP) and resistance to the flow.
→ F=∆PR
=L
min=
mm Hgmm Hg /L/min
Flow will increase if pressure gradient is increased
Flow will increase if resistance to flow is reduced (or both!)
What if:
• Pressure gradient is increased and resistance is kept constant
o Flow would increase
Resistance is increased and pressure gradient is kept constant
• Flow would decrease
• Changing the size of the vessel has a great effect on resistance because it is inversely proportional to radius to the 4th power
→ R∝1
r 4
→ What if:
Pressure remains constant and resistance decreased by 16 fold.
• Arterioles undergo the greatest amount of radius change and thus the radius change in resistance
→ Radius is controlled by the sympathetic nervous system and epinephrine
Norepinephrine is released onto alpha 1 adrenergic receptors which causes vasoconstriction
• Which is a reduction in vessel radius and thus, it increases the resistance to blood flow
Epinephrine released from adrenal medulla àresults in beta 2 type adrenergic receptors being activated which causes vasodilation
→ Summary:
Alpha 1 adrenergic receptors causes vasoconstriction
Beta 2 adrenergic receptors causes vasodilation
→ Controlled by local chemical factors in tissues supplied by arterioles
Dilates: Include NO (Nitric Oxide) – produced by vascular endothelium
Dilates: Histamine – released by immune system due to an allergic reaction
→ Beta receptors are mainly found in the heart
→ Alpha receptors are mainly found in the GI tract
• Active Hyperemia:
→ Increases blood flow in active skeletal muscle (without sympathetic control) due to accumulation of metabolites which dilates (expands) the arteries
Metabolites include: increase in CO2, decrease O2, increase in lactic acid
Microcirculation and Exchange across Capillary Walls:
• Metaarterioles are shunts, most blood at rest will go through metaarterioles
• Most capillary beds in muscle tissue are closed at rest
• Blood is pushed (shunted) through metaarterioles to venules when the precapillary sphincters are closed
o The precapillary sphincters open when:
There is an increase in CO2 in tissue
There is a decrease in O2 in tissue
There is an increase in lactic acid in tissue
• Capillaries: where the exchange of nutrients and waste products of metabolism and oxygen and carbon dioxide occurs
• Movement across the capillary:
o Simple diffusion: a solute moves down the concentration gradient
o (Don’t exactly get this) Bulk flow: movement of water and the solutes dissolved in the water across the endothelial later through pores due to the differences in pressure between capillary and interstitial fluid
→ Capillary blood pressure: forces fluid out of capillary
→ Interstitial blood pressure: forces fluid into capillary
→ Plasma colloid osmotic pressure: force that favours movement of water into capillary
→ Interstitial fluid colloid osmotic pressure: force that favours movement of water out of capillary
• Example of movement across the capillary:
o There is high amounts of oxygen in blood à oxygen will diffuse into interstitial fluid
Capillary Filtration and Reabsorption:
→
Lymph System:
→ The small amount of fluid that is not reabsorbed by the capillaries is taken up by the lymphatic system
→ And then it is returned to the blood eventually when the lymphatic duct dumps into a major vein
→ This prevents buildup of fluid in the interstitium which could cause tissue swelling
→ Smooth muscle around the lympathatics contract and force the lymph into back into the circulation and skeletal muscle contraction forces the fluid into venous circulation
→ There are valves which prevent backflow
Veins:
• Can store about 60% of the large volume of blood at rest (capacitance)
• Veins are expandable, thin walled, with little smooth muscle or elastin
• Venous return is facilitated by:
o Venous values which prevent backflow
o Stimulated by the sympathetic nervous system which can control capacitance
o Skeletal muscle pumping which squeezes veins and forces blood into the next compartment
Control of Blood Pressure:
• Controlled by:
o Cardiac output
Heart rate à is controlled by parasympathetic and sympathetic nervous system
Stroke volume à controlled by sympathetic nervous system
o Arteriolar resistance
Controlled by the sympathetic nervous system
o Blood volume
Controlled by the kidneys
• Short term control:
o Regulation is maintained by adjustments to the cardiac output and arteriolar resistance
SUMMARY:
ANATOMY: PULMONARY SYSTEMFunctions of the Respiratory System:
• Gas exchange between air and circulating blood
• Moving air from the exchange surface of the lungs
• Protection of the respiratory surfaces
• Production of sound
• Provision of olfactory sensation
Thoracic Cage:
• It is formed by:
o A sternum
o 12 pairs of ribs
o Costal cartilage
o 12 pairs of thoracic vertebrae
• Surrounds the thoracic cavity and supports the pectoral girdle
• Provides protection for the thoracic and abdominal contents (heart and lungs)
Organization of the Respiratory System:
• Upper respiratory system:
o Nose, nasal cavity, paranasal sinuses, pharynx
• Lower respiratory system:
o Larynx, trachea, bronchi, bronchioles, alveoli
Pharynx:
• Posterior to nasal and oral cavities
• Purpose is to supply air to larynx and trachea
• Part of digestive and respiratory system
• There are three parts to the pharynx (NOL):
o Nasopharynx
Function is respiratory
It warms and moistens the air
It is a posterior extension of the nasal cavities
Extends to soft palate
o Oropharynx
Is from the soft palate to the epiglottis (the function of the epiglottis is to prevent chocking)
Has a digestive function
o Laryngopharynx
Digestive function
Lies posterior to the larynx
Epiglottis to cricoid cartilage
Larynx:
• It is a complex organ for voice production
• Connects pharynx to trachea
• It is composed of nine cartilages
• It changes in size and length of cartilage to affect vocalization
• Laryngeal Prominence = Adam’s Apple
• Three main cartilages:
o Thyroid cartilage – this is the largest
o Arytenoid cartilage
Lies superior and posterior to the cricoid
Looks like a hook
Forms cricoarytenoid joint for attachment of vocal ligament
o Cricoid cartilage – thicker and stronger
It is the only complete ring of cartilage
• Vocalization:
o Glottis is the vocal apparatus of larynx
o Rima glottdis is the aperture/opening between the vocal folds
o Shape of rima varies according to the vocalization desired.
o Vocal Folds:
True Vocal Folds:
• Controls sound production
• Consists of vocal ligament and vocalis muscle
False Vocal Folds:
• Vestibular fold
• Protective function
• Extend between thyroid and arytenoid cartilages
• The space between the false and true vocal words is the ventricle of the larynx
Trachea:
• Fibrocartilagenous tube from larynx to T4 / T5
• It is supported by incomplete cartilaginous tracheal rings
• The posterior gap of the rings is covered by smooth muscle
• Common carotid artery and thyroid gland lie laterally
• It is around 2.5 cm in diameter in adults
• Tracheostomy:
o A surgery where an incision is made between tracheal rings and a tube is inserted to maintain airways
o Opening is made between either rings 1 – 2 or rings 2 – 4
Esophagus:
• Muscular tube after the laryngopharynx
• Consists of:
o Upper 1/3 being voluntary
o Middle 1/3 being a mixture of both voluntary and smooth muscle
o Lower 1/3 being smooth muscle
• Travels posterior to trachea and pierces diaphragm to enter stomach
o Food moves down the stomach via parastalsis (which is the involuntary squishing of food)
Trachea and Bronchi:
• Trachea bifurcates into two primary bronchi
o Each primary bronchi is supported by hyaline cartilage
o Each primary bronchi branches to form a bronchial tree that goes into a lobe
• Primary bronchi divide to become lobar bronchi (secondary bronchi) that go into each lobe
o Two on the left side
o Three on the right side
• Lobar bronchi divide into terminal bronchioles which divide into respiratory bronchioles
Thoracic Viscera: (organs lying in the thoracic cage)
• Two lateral compartments which consist of the lungs and pleurae
o Pleurae of the lungs:
Each lung is enclosed in a serous sac
Has two continuous membrane:
• Visceral – cannot be separated from the lungs
• Parietal – lines the pulmonary cavity
• One central compartment which consists of the heart, great vessels, esophagus, trachea, thymus (a special organ of the immune system)
Lungs:
• Organs of respiration
• Separated from each other by the heart, great vessels, and viscera
• Attached to the heart and trachea by structures comprise the root of the lung (pulmonary arteries, pulmonary veins, and bronchiole structures)
• Lung has three surfaces:
o Costal surface
o Mediastinal surface
o Diaphragmatic surface
• Lung also has three borders
o Anterior – where costal and mediastinal meet anteriorly
o Posterior – where costal and mediastinal meet posteriorly
o Inferior – circumscribes the diaphragmatic surface
• Right Lung:
o Larger, wider, shorter, and heavier than the left lung
Cause the left lung as the liver in the way
And the heart is also partially in the way too
o Has three lobes:
Superior
Middle
Inferior
Superior and inferior lobes are separated by the oblique fissure
Superior and middle lobes are separated by horizontal fissures
• Left Lung:
o Left heart has a deep cardiac notch that indents the anterior border of the superior lobe
o Has two lobes:
Superior – anterior border has an indent called the cardiac impression
Inferior
Lobes are separated by the oblique fissure
Thoracic Diaphragm:
• Main muscle of inspiration
• 3 openings go through the diaphragm for three important structures:
o Aortic hiatus
o Esophageal hiatus
o Caval foramen
• When thoracic diaphragm contracts, the dome moves inferiorly (during inhalation)
o This is Boyle’s Law
Decreased pressure = increased volume
Increased pressure = decreased volume
o Pushes abdominal viscera down (inferiorly)
Mechanisms of Breathing:
→ Quiet breathing: eupnea
o Involve diaphragm, internal and external intercostals
→ Forced breathing: hyperpnea
o Involves accessory muscles as well
→ Alveoli:
o Final gaseous exchange occurs in the alveolar sacs
o Intimately located next to the bronchial capillaries which bring deoxygenated blood from heart via pulmonary arteries
o Are efficient because there is a lot of surface area and:
There is a difference in partial pressure
There is a small diffusion distance
The gas exchange involves gasses that are lipid soluble
Coordination of blood flow and airflow
SUMMARY:
ANATOMY: LYMPHATIC SYSTEMLymphatic system:
• Vast network of lymphatic vessels that are connected to lymph nodes
o Lymph nodes = masses of lymphatic tissue
• It’s the second circulatory system
• It’s job is to collect surplus tissue fluid (lymph) and send it back to the heart
• Parts of the lymph system include: spleen, bone marrow, thymus, nodes, and vessels
• Functions:
o Drainage of tissue fluid
o Collection of lymph from tissue spaces
o Transportation of lymph to the venous return system
the lymph drains into the subclavian vein
o Absorption and transportation of fat
o Defense mechanism of the body as it transports antibodies and lymphocytes to fight pathogens
• Lymph either enters the:
o Right lymphatic duct (where the lymph from the right side of the body and head enter)
o Thoracic duct (where lymph from the rest of the body enter)
• Lymph reenters venous circulatory system
Lymphoid Organs:
• Lymph nodes:
o Tonsils, dense connective tissue through the body
o Function is to filter lymph before it enters the venous circulation
o Usually the first to react to pathogens and thus, strategically placed
o Fixed macrophages
• Thymus:
o It is posterior to the sternum
o Important role in growth and development of the immune system
o Grows until puberty hits and then the thymus degrades (atrophy) into fat
o Continues to produce Tlymphocytes in adulthood
• Spleen:
o It is a nonvital organ
o Largest of the lymphatic organs
o The splenic artery is large due to the large amount of blood volume
o Function:
Blood is monitored for pathogens by Tcells
Macrophages swallow and digest debris in blood cells
Lymphocytes:
• Three type of lymphocytes:
o Tcells (thymus – dependant)
80% of the lymphocytes are Tcells
• Four types of Tcells
o Helper Tcells
Stimulate further cellmediated and antibody mediated immunity
o Cytotoxic Tcells
o Memory Tcells
Creates a memory for following exposures to the same pathogen
o Suppressor Tcells
Supresses the response after initial response
o Bcells (bone marrow)
o NK cells (natural killer)
These cells ward off cancer cells
These cells are bigger than the Tcells and the Bcells
Defense Mechanisms:
• Nonspecific defense:
o Doesn’t distinguish pathogens
o Examples: fever, skin, phagocytes, inflammation
NK cells
Mast cells, basophils
Neutrophils, eosinophils, macrophages
o Specific defenses:
It depends on the activity of lymphocytes
Example: Tcell that is manufactured for a specific bacteria
Immune Responses:
• Innate immunity (which is nonspecific)
o Don’t need previous exposure to pathogens to attack it
o Magnitude of response is always the same
• Acquired Immunity (which is specific):
o Learns to recognize the pathogen and mounts a larger attack the second time around
• Cell mediated immunity: (which is one cell signals another cell)
o Helper Tcell recognizes pathogens’ antigen
o Helper Tcells activate cytotoxic Tcells
o Cytotoxic tcell tracks and destroys the cell with that specific antigen
• Antibody mediated immunity: (antibody signals the production of more antibodies)
o Bcell recognizes foreign antigen
And then the bcell divides into plasma cells and memory Bcells
The plasma cells can produce antibodies
Memory bcells creates a memory for following exposures
o When the antibody comes in contact with the antigen:
Neutralization can happen (antibodies prevent the antigen from doing any harm)
• Enhances phagocytosis
Agglutination can happen (antibodies bring together all the antigens and stick them together)
• Enhances phagocytosis
Precipitation can occur (antibodies solubafy the antigen?)
• Enhances phagocytosis
Complement can occur (NEED EXPLANATION!)
• Leads to cell lysis (explosion!)
SUMMARY:
ANATOMY: INTEGUMENTARY SYSTEMComponents of the System:
• Accessory structures
• Subcutaneous layer
Functions of the System:
• Protection (primary function)
• Excretion
• Temperature maintenance
• Nutrient storage
• Vitamin D3 synthesis (when exposed to UV rays)
• Sensory detection (thermoreceptors, mechanoreceptors, chemoreceptors)
Cutaneous membrane
• Epidermis:
o Composed of layer of keratinocytes
Thin skin = four layers
Thick skin = five layers
o Provides mechanical protection
o Prevents fluid los
o Keeps microorganisms from invading the body
o Cells accumulate keratin and eventually are shed
o Epidermal ridges are interlocked with dermal papillae which improves gripping ability (and causes fingerprint)
o Langerhans cells (immunity)
o Merkel cells (sensitivity)
o Epidermal cells:
Synthesize vitamin D3 when exposed to the UV
Respond to epidermal growth factor
• This determines how fast our hair, skin, and nails grow, repair, and secrete
• Dermis:
o Papillary layer:
Contains blood vessels, lymphatic vessels, sensory nerves of the epidermis
o Reticular layer:
Contains network of collagen and elastic fibers to resists tension
• This give skin its elasticity, not to anchor it to anything
o Stretch marks occur because it is an excessive stretching of the dermis
It leaves patterns of collagen and elastic fibers form lines of cleavage
• It is red because it is an accumulation of red blood cells
o Reticular layer gets stretched and thus, papillary layer gets damaged and vessels rupture
Lines of cleavage are naturally occurring and allows for movement
o Cutaneous plexus arteries found in subcutaneous layer / papillary dermis
o Cutaneous sensory receptors (light touch, pressure)
o Hypodermis:
Connects skin to underlying tissue (underlying tissue = adipose or fascia)
• Keratin:
o Fibrous structural protein
o Key material in epidermis, nails, and hair
o Callus formation
o Epithelial cells become “cornified” with keratin (which makes skin waterproof)
• Skin colour:
o Depends upon:
Blood supply
How much melanin we have
Carotene
Epidermal pigmentation
Hair follicles:
• Hair originates in the follicle
• Composed of roots and shaft
• Root (papilla) surrounded by bulb and plexus
• Soft medulla and hard cortex
• Cuticle is the superficial dead protective layer
Glands:
• Sebaceous:
o Tied to the lymphatic system
o Discharge waxy sebum onto hair shaft
• Sudoriferous:
o Give you your distinct odor
o Apocrine sweat glands
Produce odor
o Merocrine sweat glands:
Perspiration
• Mammary:
o Structurally similar to apocrine sweat glands
• Ceruminous:
o In ear, it produces waxy cerumen to protect the ear
Nails:
• Nail body covers the nail bed
• Nail production occurs at the roots
• Cuticle (eponychium) lies over the root
Injury and Repair:
• Regenerates easily
• Regeneration process includes:
o Scabbing
o Granulation tissue
o Scar tissue
SUMMARY:
PHYSIOLOGY: PULMONARY PHYSIOLOGY Anatomical Features of the Pulmonary System:
• Airways:
o There is an increase in the amount of smooth muscle we see in the airways
Parasympathetic nervous system stimulus of the smooth muscle results in constriction of the bronchioles
Sympathetic nervous system stimulus of the smooth muscle results in dilation of the bronchioles
• Alveolar Sac: a cluster of alveoli with a common opening
• Alveoli:
o The alveolar wall is composed of two types of cells:
Type I: sometimes are called pavement cells
• Usually make up the alveolar wall
• Are thin and flat
Type II: produce pulmonary surfactant
• Surfactant is a type of phospholipid
o Because water coats both type I and type II surfactant breaks the water molecule bond in order for the alveoli to expand
• Type two is thicker and isn’t as common as type I
o Alveolar macrophage attacks any bacteria or virus
o The thin walls of the alveoli and high surface area allow high permeability for gas diffusion
• Pleural sac:
o Visceral Pleura:
This is connective tissue surrounding the lung
This layer cannot be separated from the lung
o Parietal Pleura:
Connective tissue lining the inside of the thorax
o Intrapleural Space:
Thin and fluid filled
This is lubrication and glue
o The visceral and parietal pleura are in very close proximity, the only thing separating the two is the intrapleural space which is filled with the intrapleural fluid
Respiratory Mechanics:
• Pressures:
o Atmospheric Pressure: pressure of the atmosphere, decreases as elevation increases
o Intraalveolar Pressure / Intrapulmonary pressure: pressure inside each alveoli
o Intrapleural Pressure: pressure inside pleural space, this is always below the atmospheric pressure
Why is intrapleural pressure below the atmospheric pressure? (or subatmospheric)
• If the pressure is equal or greater than the atmospheric pressure then the lung wouldn’t expand
• Because of the tendency for the thorax to expand outwards
• Because of the tendency of lung to recoil inward (collapse)
o These two forces try force the lung apart, but the thin layer of intrapleural fluid between the two layers prevents it from occurring
The pressure inside the intrapleural space is negative, and thus, it forces the two pleural together and prevents it from separating
o Pneumothorax:
Lung would collapse!
o Transpulmonary Pressure: difference between intraalveolar (intrapulmonary) pressure and the intrapleural pressure
• Inhalation / Inspiration:
o Contraction of: (which results in the thorax having volume)
External intercostal muscles ribs move up and out
Diaphragm – moves down
o Changes in Pressure:
Intrapulmonary: pressure decreases as you inhale because the external intercostal muscles and diaphragm moves out of the way
Transpulmonary: stays relatively the same due to the fact that the intrapulmonary pressure decrease so does the intrapleural pressure
Intrapleural pressure: decreases, but then the pressure is relatively more negative to the atmospheric which forces the two pleura together and prevents the separation
o Summary:
Inhalation:
→ Increase in volume (Boyle’s Law: increase in volume = decrease in pressure)
→ Decrease in intrapleural pressure
• Exhalation / expiration:
o Relaxation of: (which results in more pressure)
External intercostal muscles
Diaphragm
o The intrapulmonary pressure is greater or equal to the atmospheric pressure
o Intrapleural pressure returns to normal
Compliance:
• Change in alveolar volume is not only a function of the change in thoracic pressure, but also in the compliance of the alveoli
• Compliance:
o Ease of filling of the alveoli
o Change in volume of the alveoli / unit change in pressure
• What affects compliance?
→ Thickness of the alveolar wall (thinner the better)
The thinner the better
→ Size of the alveoli at the start of inhalation (larger the alveoli the better)
The smaller the alveoli at the start of inspiration the harder it is to fill the alveoli
The larger the alveoli the better
→ Surface tension of alveoli (less surface tension is better)
The less surface tension the better
Lung Volume:
• Definitions:
→ Respiration (ventilation) rate: number of breaths taken per minute ( ¿of breathsmin )
→ Tidal volume: amount of air moved in and out of lungs per minute
( amount of air∈¿out of lungsbreath )
→ Minute ventilation: tidal volume times respiratory rate
( ¿of breathsmin )×( amount of air∈¿out of lungs
breath )=amount of airmin
→ Dead space: amount of air in the airway that doesn’t undergo gas exchange
→ Alveolar ventilation: Tidal volume minus dead space times the respiratory rate
(Tidal volume−dead space ) x( ¿of breathsmin )= volume
min
→ Vital capacity: max expiration following a max inspiration
Gas Exchange:
• All about the movement of oxygen and CO2 the alveolar air, blood, and tissues
• It is based upon the partial pressure of gasses in these compartments
o Gas always moves from an area of high partial pressure to an area of low partial pressure
• Partial pressure = fraction of a gas in the atmosphere x the atmospheric pressure
• Partial pressure in the atmosphere is different from the partial pressure in the alveoli
o Fraction of oxygen = 21% (PN2)
o Fraction of nitrogen = 79% (PO2)
o Fraction of carbon dioxide and other gases: less than 1% (PCO2)
• Gases also exert a partial pressure on liquid
o It depends upon the partial pressure of the gas on top of the liquid or mixed in with the liquid
o When a liquid is exposed to the atmosphere, it will eventually reach the same pressure as the atmosphere
• Oxygen:
o PO2 in dry air versus at sea level is different because:
Due to the mixing of air in the dead space and fresh air during inhalation
• Dead space air = low in oxygen
• Fresh air = high in oxygen
• Thus, there is a reduction in the PO2 levels
Humidification of air during inhalation
• Reduces fraction of oxygen in the alveoli
• Reduces PO2
o We will assume that we are at sea level under resting conditions which means that the PO2 levels in alveolar air is 100 mmHg
• Carbon dioxide: PO2 levels in alveolar air is 40mmHg at sea level because:
o Mixing of fresh air with dead space
o Rate of which CO2 is delivered to the lung from the blood
• Fick’s Law of Diffusion:
o Rate of diffusion of gases across the alveoli is governed by Fick’s Law
Surface area increase = good
Partial pressure increases = good
Thickness of alveoli increases = bad
(k x A x ( P2−P1
D ))=rate of diffusion
K = diffusion coefficient of gas
A = surface area
D = thickness of the barrier
P2 – P1 = partial pressure gradient for gas
Gas Transportation:
• Vast majority of oxygen carried in blood is carried by hemoglobin found in red blood cells
o It can carry 20mL oxygen/100 mL
o Because cardiac output cannot deliver amount of blood desired
• Binding of oxygen to hemoglobin:
o Hemoglobin is made up of four protein subunits called globulins
2 Alpha
2 Beta
All four have a porplyrin ring (a heme group) that contains ferrous iron which is the only iron capable of transporting oxygen.
o The curve is Sshaped (it is called sigmoidal curve)
o Cooperativity: the binding of one oxygen molecule facilities the rapid binding of other oxygen molecules
o Full saturation of hemoglobin occurs around 60 mmHg
o Hemoglobin only unloads about 25% 30% of its oxygen to diffuse into the tissue
o We usually still have 20% to 40% of oxygen left in the hemoglobin at all times (unless you are dead)
• Bohr’s Shift:
o The rightward shift of the sigmoidal curve due to the increase of carbon dioxide levels helps unload more oxygen at the tissue level
It doesn’t affect the ability to saturate at the level of the lung
Only helps to unload the oxygen at the tissue level
o Things that affect affinity of hemoglobin to oxygen:
Increased CO2 levels
Lower pH
Increase in temperature
Increase in 2,3 diphosphoglycerate – occurs when exposed to high altitudes
• CO2 can be in three different forms in the blood:
→ Dissolved in the blood plasma
→ In the form of bicarbonate (most of the CO2 in the blood is in this form)
→ CO2 bound to hemoglobin
At the tissue level, oxygen is released and carbon dioxide is picked up
At the alveolar level, oxygen is picked up and carbon dioxide is released
Control of Ventilation:
• Control is centered in the medulla oblongata and pons region of the brain stem
o Medullary Respiratory Center:
1. Dorsal Respiratory Group: Passive
• Controls quiet breathing during rest
• Controls the intercostal neurons (external intercostal muscles) and the phrenic neurons (diaphragm)
2. Ventral Respiratory Group: Active
• Active during time of increased needs for ventilation (exercise)
• Stimulates internal intercostal and abdominal muscles during forced expiration
Control of Inspiration and Expiration:
1. Central Pattern Generator Cells:
o Sends commands to regulate frequency for firing of Dorsal Regulation Group cells
o These cells are called preBotzinger cells
2. Pontine Respiratory Center:
o Fine tunes period of inhalation and exhalation via signals to the Dorsal regulation Group cells
3. Pulmonary Stretch Receptors and HeringBreuer (stretch) reflex:
o HeringBreuer (stretch) reflex if there is an overinflation of the lung, then it signals the Dorsal Regulation Group to stop further inhalation
4. Chemoreceptors:
o Peripheral: carotid bodies and aortic bodies
Faster to react than central chemoreceptors
o Central: it only monitors the cerebral spinal fluid pH
They are a lot more sensitive to the changes to the PCO2
How they work:
→ CO2 can cross the blood brain barrier and it would enter the cerebral spinal fluid
→ Carbon dioxide + water in the cerebral spinal fluid à carbonic acid
→ Carbonic acid à HCO 3 + H+
→ H+ stimulates control chemoreceptors which increases ventilation
Pulmonary Pathophysiology:
• Hypoxia: reduced availability of oxygen at the tissue level
o Four types of hypoxia:
1. Hypoxic hypoxia:
• Due to a lack of oxygen in the atmosphere
2. Anemic hypoxia:
• Due to anemia which is a reduction in hemoglobin
3. Circulatory hypoxia:
• Due to poor circulation
4. Histotoxic hypoxia:
• Due to the inability to use oxygen in the cells (ex. cyanide poisoning)
• Pulmonary obstructions:
o All pulmonary obstructions result in the same effect on ventilation, which is reduced ability to forcefully exhale due to either:
1. Increased airway resistance
2. Reduced elastic recoil
o Type of Obstructions:
1. Chronic Bronchitis: narrowing of airways due to mucus
2. Asthma: narrowing of airway due to the contraction of smooth muscles around airway
3. Emphysema: due to the breaking down of the alveolar walls which is due to an enzyme that is released that destroy elastin
SUMMARY: