Chapter 10-11 Review

The Heart: Heart WallThe Heart: Heart Wall

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Three layers Epicardium

Outside layer This layer is the parietal pericardium Connective tissue layer

Myocardium Middle layer Mostly cardiac muscle

Endocardium Inner layer Endothelium

The Heart: CoveringsThe Heart: Coverings

Slide 11.3Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Pericardium – a double serous membrane Visceral pericardium

Next to heart

Parietal pericardium

Outside layer

Serous fluid fills the space between the layers of pericardium

The Heart: ChambersThe Heart: Chambers

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Right and left side act as separate pumps Four chambers

Atria Receiving chambers (thinner walls)

Right atrium Left atrium

Ventricles Discharging chambers

Right ventricle (2nd thickest) Left ventricle (thickest)

The Cardiovascular System2. Blood Vessels -A network of tubes

–Arteriesarterioles move away from the heart•Elastic Fibers•Circular Smooth Muscle

–Capillaries – where gas exchange takes place.•One cell thick•Serves the Respiratory System

–VeinsVenules moves towards the heart•Skeletal Muscles contract to force blood from legs back to heart•One way leaflet valves

– When the valves no longer meet properly (valvular incompetence) varicose veins form b/c of pooling blood/ backflow

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Regulation of the Heart• Intrinsic regulation: Results from normal functional

characteristics—initiated by heart’s own pacemaker nodes, not on neural or hormonal regulation– Starling’s law of the heart--stroke volume of the heart increases in

response to an increase in the volume of blood filling the heart (the end diastolic volume) when all other factors remain constant (more blood in the heart=stronger heart muscular contraction)

• Extrinsic regulation: Involves neural and hormonal control– Parasympathetic stimulation (by medulla oblongata)

• Supplied by vagus nerve, decreases heart rate, acetylcholine secreted

– Sympathetic stimulation• Supplied by cardiac nerves, increases heart rate and force of contraction,

epinephrine and norepinephrine released

Heart Homeostasis• Effect of blood pressure

– Baroreceptors monitor blood pressure

• Effect of pH, carbon dioxide, oxygen– Chemoreceptors monitor

• Effect of extracellular ion concentration– Increase or decrease in extracellular K+ decreases heart rate

• Effect of body temperature– Heart rate increases when body temperature increases, heart rate

decreases when body temperature decreases

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Arteries: Built for their job• Arteries

– blood flows away from heart– thicker walls

• provide strength for high pressure pumping of blood

– elastic & stretchable • maintains blood

pressure even when heart relaxes

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Major arteries

pulmonaryartery

pulmonaryartery =to lungs

aorta carotid = to headto brain & left arm to right arm

coronary arteries

to body

Veins: Built for their job• Veins

– blood returns back to heart– thinner-walled

• blood travels back to heart at low speed & pressure

• why low pressure?– far from heart

• blood flows because muscles contract when we move – squeeze blood through veins

– valves in large veins• in larger veins one-way valves

allow blood to flow only toward heart

Open valve

Blood flowstoward heart

Closed valve

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Structure-function relationship• Capillaries

– very thin walls – allows diffusion of

materials across capillary• O2, CO2, H2O,

food, wastebody cell

O2

food

waste

CO2

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Blood Vessels: Anatomy

Slide 11.25Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Three layers (tunics)Tunic intima

Endothelium

Tunic media

Smooth muscle

Controlled by sympathetic nervous system

Tunic externa

Mostly fibrous connective tissue

• 2 part system– Circulation to lungs

(pulmonary)• blood gets O2 from lungs)

• drops off CO2 to lungs

• brings O2-rich blood from lungs to heart

– Circulation to body (systemic)• pumps O2-rich blood to body

• picks up nutrients from digestive system

• collects CO2 & cell wastes

Circulation of Blood

lungs

body

Circulationto lungs

Circulationto body

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Vertebrate circulatory system

lungs

body

• 2 part system

arteryto body

arteryto lungs

vein from lungsto heart

vein from bodyto heart

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Pathway of the blood•PULMONARY (deoxygenated)•Superior/ Inferior Vena Cava•Right Atrium•Tricuspid Valve•Right Ventricle•Pulmonary Semilunar Valve•Lungs•Pulmonary arteries•SYSTEMIC •pulmonary veins•Left Atrium•Bicuspid Valve•Left Ventricle•Aortic Semilunar Valve•Aorta•To the body’s organs & cells

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Cardiac Muscle

• Elongated, branching cells containing 1-2 centrally located nuclei• Contains actin and myosin myofilaments • Intercalated disks: Specialized cell-cell contacts• Desmosomes hold cells together and gap junctions allow action potentials• Electrically, cardiac muscle behaves as single unit

Conducting System of Heart

Refractory Period

• Absolute: Cardiac muscle cell completely insensitive to further stimulation

• Relative: Cell exhibits reduced sensitivity to additional stimulation

• Long refractory period prevents tetanic contractions

Electrocardiogram• Action potentials through

myocardium during cardiac cycle produces electric currents than can be measured

• Pattern– P wave

• Atria depolarization

– QRS complex• Ventricle depolarization• Atria repolarization

– T wave: • Ventricle repolarization

EKG Interpretation

• P-wave– SA node sends signal through atria muscle

–Atria depolarize (becomes more positive)

P

Conducting System of Heart

EKG Interpretation

• P-wave–Graph Result: small upward curve

– Result: Current passes over Atria

P

EKG Interpretation

• P Q segment–Graph Result: Flat line –Response: Atrial contraction time

P

Q

EKG Interpretation

• QRS complex (or interval)–AV node sends signal through ventriclular muscle

–Ventricles depolarize (change charge sign)

Q

R

S

P

EKG Interpretation

• QRS complex–Response: Current passes over ventricles

Q

R

S

P

EKG Interpretation

• S T segment–Graph: rise, flat line and bump–Response: Ventricular contraction time

Q

R

S

PT

EKG Interpretation

• T-wave–Ventricles repolarize– Response: Return to resting potential

Q

R

S

PT

EKG Interpretation

• U-wave (if present)–Repolarization of papillary muscles

Q

R

S

PT U

Heart Sounds

• First heart sound or “lub”– Atrioventricular (AV) valves close at beginning of ventricular

systole (contraction)

• Second heart sound or “dub”– Results from closure of aortic and pulmonary semilunar valves at

beginning of ventricular diastole (relaxation)

• Third heart sound (occasional)– Caused by turbulent blood flow into ventricles and detected near

end of first one-third of diastole

Pulse

Slide 11.35Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Pulse – pressure wave of blood

Monitored at “pressure points” where pulse is easily palpated

Figure 11.16

Blood Vessels: Anatomy

Slide 11.25Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Three layers (tunics)Tunic intima

Endothelium

Tunic media

Smooth muscle

Controlled by sympathetic nervous system

Tunic externa

Mostly fibrous connective tissue

Plasma Proteins

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Albumin – regulates osmotic pressure

Clotting proteins – help to stem blood loss when a blood vessel is injured

Antibodies – help protect the body from antigens

Platelets

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Derived from ruptured multinucleate cells (megakaryocytes)

Needed for the clotting process

Normal platelet count = 300,000/mm3

Platelet Plug Formation

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Collagen fibers are exposed by a break in a blood vessel

Platelets become “sticky” and cling to fibers

Anchored platelets release chemicals to attract more platelets

Platelets pile up to form a platelet plug

pump (peak pressure)_________________fill (minimum pressure)

Cardiac CycleHow is this reflected in blood pressure measurements?

chambers fill

ventriclesfill

ventriclespump

systolic________diastolic

110________80

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Cardiac Cycle

• Heart is two pumps that work together, right and left half

• Repetitive contraction (systole) and relaxation (diastole) of heart chambers

• Blood moves through circulatory system from areas of higher to lower pressure.– Contraction of heart produces the pressure

Cardiac Cycle