Module 12

respiratory system function

• supply body tissues with oxygen\

• dispose of CO2

respiration includes…

• pulmonary ventilation

• gas exchange

alveoli

• saclike dilation

• site of gas exchange with the blood

• big surface area in contact with capillaries for quick diffusion

elasticity

tendency of a structure to recoil to its initial dimensions after being distended

acidosis

increase in H+ concentration of the blood that lowers pH

type 1 alveolar cell

forms continuous layer lining the air-facing surface of the pulmonary alveoli

hypoventilation

plasma concentration of CO2 is abnormally increased, inadequate pulmonary ventilation

boyle’s law

pressure of given quantity of a gas is inversely proportional to its volume

alkalosis

decrease in H+ concentration of blood that raises pH

partial pressure

pressure of a particular gas in a mixture

transpulmonary pressure

pressure difference keeping the lungs against the chest wall

diaphragm

primary muscle of ventilation

lung compliance

change in lung volume per change in transpulmonary pressure

chemoreceptor

receptor sensitive to chemical changes such as pH, O2, CO2

deoxyhemoglobin

produced when oxyhemoglobin releases oxygen

ventilation

exchange of air between atmosphere and alveoli

oxyhemoglobin

oxygen bound on hemoglobin

hyperventiliation

high rate and depth of breathing resulting in a decrease in blood CO2 concentration below normal

intrapleural space

potential space between the visceral and parietal linings

surfactant

reduces surface tension between fluid and alveolar surface, increases lung compliance

intrapulmonary space

space within air sacs and airways

type 2 alveolar cell

pulmonary cells that produce surfactant

pulmonary ventilation

exchange of air between atmosphere and alveoli

components of gas exchange

• external respiration

• internal respiration

external respiration

• movement of O2 from lungs into blood

• CO2 from blood to lungs

internal respiration

• movement of O2 from blood into tissue cells

• CO2 from cells into blood

upper airway

air comes in and travels to larynx

air way ends at the

alveolar sacs

respiratory zone

where gas exchange happens

conducting zone

everything else

epithelial surfaces contain…

cilia

cilia

secrete mucus and keep lungs clear of particulate matter

particulates

dust, foreign contaminants

in the respiratory zone the air is…

* 37 degrees C
* temp and moisture is constant

respiratory system located in …

thorax (neck to diaphragm)

lungs

passive, elastic, volume fluctuates

all pressures are relative to…

atmospheric pressure (760mm Hg at sea level)

inverse relationship between

pressure and lung volume

intra-alveolar pressure (intrapulmonary)

changes to drive movement of air

pressure equation

P(transpulmonary) = P(alveolar) - P(intrapleural)

intrapleural pressure is always less than

alveolar pressure

intrapleural pressure

pressure in pleural space

inspiration initiated by

motor neurons firing APs to intercostal muscles and diaphragm

most important inspiratory muscle

diaphragm

active movement

inspiration

expiration initiated by

motor neurons decrease APs to diaphragm and intercostal muscles, causing them to relax

passive movement

expiration

role of nervous system

• receive info

• processes and responds

respiratory rhythm generated in…

medulla oblongata

motor neurons

breathing depends on these muscle movements, especially diaphragm

carotid bodies

strategically located to monitor oxygen supply to brain

peripheral cemoreceptor

responding to changes in H+ concentration

input from receptors modifies

rate and depth of breathing

when muscles contract in chest wall

chest expands

during inspiration…

diaphragm contracts downward and the thoracic cavity is larger

dalton’s law

the pressure each gas exerts is independent of the pressure of other gases

oxygen diffuses from

alveoli to plasma (high to low concentration)

during exercise

the O2 gradient from blood to tissue increases

2 forms of oxygen in blood

• dissolved in plasma and erythrocyte cytosol

• combined with hemoglobin molecules in erythrocyte

heme

iron-containing pigment, binding site

factors affecting movement of O2 on hemoglobin to tissues

• concentration

• affinity (changes in pH or temp can affect affinity)

affinity should be

sufficient to hold bond of O2 to the iron on hemoglobin but not so high that it prevents unloading

only dissolved O2 contributes to

pressure of O2 of the blood

CO2 produces

H+ which causes toxicity

forms of transport for CO2

• 10% dissolves in plasma

• some react with hemoglobin

• 60-65% is converted to HCO3-

CO2 movement in tissues and lungs

• chloride shift retains electrical neutrality of cell

• H+ in red blood cell buffered by deoxyhemoglobin, H+ in plasma buffered by bicarbonate moving out

• bicarbonate builds up, leaves down its gradient

• Cl- is attracted into cell with movement of bicarbonate and trapping of H+

range for pH of blood

7\.35-7.45

blood pH maintained thru

• lungs regulate CO2

• kidneys regulate bicarbonate

respiratory acidosis

arterial H+ concentration increased due to CO2

respiratory alkalosis

results from decreased arterial CO2 pressure and H+ concentration