Respiratory System

• Involves the organs that exchange gases between the atmosphere and our bodies

• Respiration: refers to the gaseous exchange between the atmosphere, the blood and the body cells

• The cardiovascular system transports the gases

5 Events of respiration

1. Pulmonary ventilation: moving air in and out of the lungs ( breathing)

2. External respiration: exchange of gases between blood and lungs

3. Gas transport: by cardiovascular system (blood)

4. Internal respiration: exchange of gases between blood and various tissue cells

5. Cellular respiration: the production of CO2

and consumption of O2 during metabolism

Respiration: If breathing stops

• 4-5 minutes: loss of consciousness

• 7-8 minutes: brain damage

• 10 minutes: death

• Relaxed adult breath 9-20 times per minute, ventilates 5-6 liters of air

Respiratory Organs

• Nose: warms, moistens, filters air ( in addition to smell and being a resonating chamber for speech)

• Pharynx: (throat) composed of 3 areas

a) nasopharynx: respiratory air passage

b) oropharynx: respiratory and digestive functions

c) laryngopharynx: same as oropharynx

• The 2 openings of the auditory tube ( in the nasopharynx) allow for pressure equalization between the middle ear and the atmosphere)

• Tonsils: a mass of lymph tissue guarding the passageways.

• Larynx: ( voice box) connects pharynx with the trachea

Larynx: contains cartilage

• Thyroid cartilage: adams apple

• Epiglottis: a flap of tissue which closes off the trachea allowing food to pass into the esophagus rather than the trachea

• Cricoid cartilage: ring of cartilage which connects larynx and trachea ( functions in protection)

There are also 2 pairs of mucus membrane folds in the larynx

1. Ventricular folds: ( upper folds) called false vocal cords. Function in protecting your vocal cords and holding your breath.

2. Vocal folds ( lower folds) the vibration of these folds produces sound

Testosterone: causes cartilage growth during puberty resulting in longer folds, deeper ( base) sound and bigger adam’s apple

Trachea (windpipe)

• Is about a 5 inch tube anterior to the esophagus• The trachea walls consist of a stack of “C”

shaped hyaline cartilage rings with smooth muscle attached to the open cartilage ends

• This allows the esophagus to expand into the trachea during swallowing

• Inside the cartilage is the layered psudostratified cilliated columnar epithelium with goblet cells

Bronchial tree ( in order)

• Trachea• primary bronchi• secondary bronchi all columnar ep• tertiary bronchi• Bronchioles• Terminal bronchioles all cuboidal ep• Respiratory bronchiole• Alveolar duct• Alveolar sacs all squamous ep• Alveoli with external respiration

Lungs

• Paired organs found in the thoracic cavity,• Covered by 2 layers of serous membranes

( called pleural membranes)• The lungs are divided into lobes, then

segments, then lobules which increase surface area

• EX. A 150 pound person has approximately 100 square yards of alveoli walls for gas exchange ( ½ tennis court)

Gas Exchange• External respiration: takes place by diffusion across the

cell membrane of the alveoli to the capillaries ( oxygen moves into the capillaries and carbon dioxide moves from the capillaries into the alveoli)

• Pulmonary respiration(breathing) consists of 2 stages:

1. Inspiration: occurs when intrapulmonic ( within lungs) pressure is below atmospheric pressure. Contraction of diaphragm and external intercostal ( between ribs) muscles increase the size of the thoracic cavity and thus the lungs expand and pressure in lungs decreases so air flows from high pressure to low pressure

2. Expiration: the opposite, muscles relax. Volume decreases ( air leaves) and pressure increases.

The movement of air in and out depends on pressure changes created by changing the volume of lthe lungs.

Breathing and lung capacity

• Tidal volume: the amount of air expelled during a normal breath.

• Vital capacity: The largest amount of air that can be exhaled after drawing a deep breath.

• Lung Capacity: add vital capcity and residual volume

• Residual volume: in men it is 1200ml and females it is 100ml

Remember

• Boyles law: if volume increases then pressure decrease and vice versa

• Volume changes lead to pressure changes in the lungs• Daltons law: each gas in a mixture of gases ( ex air)

exerts its individual pressure, as if the other gases were not their

• So each gas has what is called a partial pressure.• This is relevant to respiration because oxygen and

carbon dioxide can diffuse in opposite directions ( each moving from an area of higher pressure to an area of lower pressure)

Remember

• Henry’s law: the amount of a gas which will dissolve in a liquid depends on that gases partial pressure and is solubility

• The solubility of the gas varies greatly due to :

• Carbon dioxide is very soluble

• Oxygen is less soluble

• Nitrogen almost not at all

• Throughout the system ( both internal and external) from lungs to blood to various tissues and back again, both oxygen and carbon dioxide move by diffusion

• oxygen from higher concentration in atmosphere to lower concentration in the cell and carbon dioxide does this oppositely

Transport of respiratory gases

• Is a function of blood• Oxygen hardly dissolves in water ( blood

plasma) so diffusion alone would not allow blood to carry enough oxygen for metabolic needs

• 97% of oxygen in the blood is carried by molecules called hemoglobin in RBCs

• Hemoglobin is a large protein with 4 pigment portions called heme rings each having a centrally located iron atom

Your body has:

• 3 trillion RBCs

• Each RBC carries 250 million hemoglobin molecules

• Each hemoglobin molecule carries 4 atoms of oxygen

• That’s a lot of AIR

The attraction of oxygen and hemoglobin is affected by

• Partial pressure of oxygen: higher PO2, the more O2 will combine with hemoglobin

• pH: increase acidity causes a release of O2

• PCO2: higher PCO2 causes a release of O2

• Temperature: increase temperature hastens release

• CO2 is much more soluble in blood than is O2

• Almost 80% of CO2 produced by cells is carried dissolved in the blood plasma and most is converted into a carbonic acid

• The amount of CO2 in your blood affects the pH of your blood

• Excess CO2 leads to respirator acidosis and insufficient CO2 causes respiratory alkalosis

• Since the body is very intolerant of even the slightest pH changes, it controls CO2 levels by controlling the frequency of expiration

Respiratory disorder

• Hypoxia: low levels of oxygen physiologically available

• Hypoxic hypoxia: low PO2 in blood due to high altitudes, blocked or fluid filled lungs

• Bronchitis: inflammation of seromucosa and goblet cells in the bronchial airways cases excess mucus and coughing

• Pneumonia: inflammation of alveoli, they fill with fluid reducing O2 that diffuses

• Asthma: muscle spasms in the smooth muscles of bronchial tree…usually due to allergies

• Emphysema: really a symptom.. some irritant ( smoking or dust) builds upon the alveolar walls and they lose their elasticity…later the walls break down and decrease the lung volume

Human Gas exchange

• Air moves into nose --- flows past pharynx----to the trachea--- to the bronchi----to the lungs

• When air reaches the lungs it has filtered debris and warmed the air to body temperature

• The trachea and bronchi are lined with cilia that eat upward, carrying mucus, dust and particles

• The hard and soft palates separate the nasal cavities from the mouth

• Air and food passages cross in the pharynx, the danger of choking is offset by providing alternative paths for breathing

• Air flows past the pharynx through the glottis into the larynx, which is protected by the epiglottis

• At the edge of the glottis are vocal cords, when air is passed across them, tissue vibrate creating vocal sounds

• From the larynx, air flows down the trachea too the bronchi

• The larynx is held open by cartilage that forms the adam’s apple

• The trachea wall is reinforced by “C” shaped cartilage

• When food is swallowed, the larynx rises and the glottis is closed y the flap of tissue called the epiglottis

• Backward movement of the soft palate covers the entrance to the nasal passage, food is directed down

• Within the lungs, each bronchus branches into numerous bronchioles that conduct air to the alveoli

• The alveoli are microscopic air sacs

• Gas exchange in the lungs and the tissue is brought about primarily by diffusion

Repiratory Tract health

• The entire respiratory tract has a warm, wet mucous membrane lining exposed to the environmental air

• The tract gets infected:

• Droplets from a single sneeze carry billions of bacteria or viruses

• The mucus membranes of the respiratory tract are protected by mucus

• If the number of infectious agents is large or resistance is inadequate, respiratory infections can result

• Ex: strept throat• Pulmonary tuberculosis The classic symptoms of

active TB infection are a chronic cough with blood-tinged

sputum, fever, night sweats, and weight loss

• Pneumonia

Respiratory System