DIBM 712- Physiology of the Respiratory System

movement of air into and out of lungs

ventilation

Respiration

diffusion of gas across plasma membranes

External respiration

gas exchange between air in lungs and blood

Internal respiration

gas exchange between blood and tissue

conducting zone

for movement of air- nose to small bronchioles

Respiratory zone

for gas exchange- alveoli and respiratory bronchioles

to accomplish gas exchange, what four processes must occur

ventilation, pulmonary respiration, gas transport, systemic respiration

Why does chest expand during inhalation

increasing volume of thoracic cavity decreases pressure and allows air to flow in

why would someone's neck muscles hurt when picking up running again

increased work of scalene muscles to increase breathing rate

what chemical mediators are produced by respiratory system

ACE

Critical function of respiration besides gas exchange

regulate blood pH

Which bronchioles do not have cartilage and are targeted by EPI and NE due to presence of smooth muscle

terminal bronchioles

When someone is having an asthma attack, what occurs

EPI causes terminal bronchioles to constrict and limit air exchange

Bronchodilation

relaxation of smooth muscle causes decreases resistance to airflow to increase airflow

Bronchoconstriction

contraction of smooth muscle causes increases resistance to airflow and decreased airflow

SNS stimulation causes bronchodilation or bronchoconstriction

bronchodilation

Site of pulmonary gas exchange

alveoli

since alveoli have no cilia, what removes debris

macrophages

Alveolar sacs

chambers connected to two or more alveoli

what would happen to diffusion rates of oxygen if we had simple cuboidal cells in our alveoli

decreased diffusion

Why do we have simple squamous cells in alveoli

quicker oxygen diffusion

Sympathetic nervous control of bronchioles

NE and EPI secreted by adrenal medulla acts on B adrenergic receptors to cause dilation

Parasympathetic nervous control of bronchioles

vagus nerve secretes Ach causing bronchoconstriction

what affect does Atropine have on bronchioles

blocks Ach and relaxes passageways

which muscles increase volume of cavity

muscles of inspiration- diaphragm, external intercostals, (primary) pectoralis minor, scalenes (secondary)

which muscle contains a central tendon

diaphragm

what muscles decrease volume of cavity during forced expiration

muscles of expiration- internal intercostals, transverse thoracic, abdominal

resting respiration requires only

diaphragm relaxation

function of pleural cavity

serous fluid allows pleura to slide past each other which allows lungs to fill with air and recoil

pleural cavity is a _____ space

potential

contraction of diaphragm does what to respiration

increases thoracic cavity volume which decreases pressure to allow air flow in

pressure and volume are ______ proportional

inversely

Air flows _____ its pressure gradient

down

Airflow=

change in pressure/resistance

Barometric air pressure

air pressure outside body

Alveolar pressure= atmospheric pressure

no air movement

Alveolar pressure < atmospheric pressure (due to increase in thoracic volume)

air moves into lungs

atmospheric pressure at sea level

750 mmHg

Alveolar pressure > atmospheric pressure (due to decrease in thoracic volume)

air moves out of lungs

When does alveolar pressure = atmospheric pressure

at the end of inspiration when there is no air movement and at the end of expiration when there is no air movement

what allows lung to expand with an increase in thoracic volume

suctioning effect of parietal and visceral pleura

Pneumothorax

air in the pleural cavity

If the visceral and parietal pleura separate, what happens

pleural pressure becomes zero and lung collapse

tall, young, thin men are more likely to have

spontaneous pneumothorax

Lung recoil

tendency for lungs to decrease in size after being stretched, due to elastic recoil and surface tension

Elastic recoil

elastic fibers in alveolar walls return to original shape after being stretched

Surface tension of lungs

film of fluid lining alveoli where water interfaces with air- increased tension will make lungs collapse

what is needed to prevent collapse of lungs

surfactant

how does surfactant prevent collapse of lungs

decreases surface tension

what is surfactant produced by

type II pneumocytes

what type of pleural pressure causes lung expansion during inspiration

negative

increasing alveolar ventilation will do what to concentration of gas

decrease

Is increased respiratory rate better for gas exchange and diffusion of gasses into tissues?

Only up to a point- if it's too rapid there is less time for diffusion to occur and the concentration of gas decreases

Ideal Gas Law

PV=nRT

Boyle's Law

pressure and volume are inversely proportional

Tidal volume

Amount of air that moves in and out of the lungs during a normal breath

Expiratory reserve volume

Amount of air that can be forcefully exhaled after a normal tidal volume exhalation

Residual volume

Amount of air remaining in the lungs after a forced exhalation

inspiratory reserve volume

Amount of air that can be forcefully inhaled after a normal tidal volume inhalation

Inspiratory capacity

tidal volume + inspiratory reserve volume

vital capacity

The total volume of air that can be exhaled after maximal inhalation.

Functional residual capacity

expiratory reserve volume + residual volume

Total lung capacity

vital capacity + residual volume

Increased scar tissue in alveoli does what to diffusion

slows diffusion

Respiratory membrane

Surfactant layer, Alveolar epithelium, capillary endothelium, fused basement membrane, interstitial fluid

Type I pneumocytes

Thin squamous epithelial cells, form 90% of surface of alveolus. Gas exchange.

Type II pneumocytes

cube shaped secretory cells producing surfactant

Why do you have to ascend to the surface slowly when scuba diving

nitrogen gas comes out of solution at lower pressures and forms bubble which can block blood flow

Surface tension in the lungs causes

contractile force

Dalton's law

total pressure is the sum of the individual pressures of each gas

Pressure exerted by each type of gas in a mixture

partial pressure

is inspired air the exact same composition as expired air

no

why are alveolar air and atmospheric air composition different

alveolar air is only partially replaced by atmospheric air, oxygen is being absorbed into pulmonary blood, CO2 is diffusing into alveoli, air is humidified

Solubility coefficient

how soluble a gas is in a liquid

diffusion coefficient

rate at which gas diffuses into and out of a liquid or tissue

solubility coefficient and molecular weight of gas

what is more soluble in water, O2 or CO2

CO2

Why do we want CO2 to be more soluble in water

to be able to diffuse faster and leave our blood

Henry's Law

concentration of gas in a liquid is determined by its partial pressure and solubility coefficient

diffusing capacity

volume of gas that will diffuse through the membrane each minute for a partial pressure difference of 1 mmHg

Diffusing capacity of O2 at rest

21 ml/min/mmHg

increases with exercise

Diffusion of gases through respiratory membrane is decreased due to what 3 major factors

decreased partial pressure gradients

increased membrane thickness

decreased surface area

physiological shunt

deoxygenated blood from lungs dilutes partial pressure of O2

why can CO2 pressure gradient be less than O2 even though the diffusion rate is faster

CO2 is more soluble

transport of oxygen

by hemoglobin (98.5%) or dissolved in plasma (1.5%)

Oxygen binds to the _____ portion of hemoglobin.

iron atom (in heme)

when first oxygen molecule binds to hemoglobin

conformational change occurs to increase Hemoglobin binding affinity to oxygen (cooperativity)

100% saturated hemoglobin

4 O2 molecules bind to one Hemoglobin

Why is carbon monoxide so dangerous

causes irreversibly binding of O2 to hemoglobin so O2 cannot be dropped off in tissue

CO2 is transported as

bicarbonate (70%), in combination with hemoglobin (23%), in solution with plasma (7%)

Is fetal or adult Hb more effective in transporting O2

Fetal

Haldane effect

Hb that has released oxygen more readily binds to CO2

CO2 combining with water in RBCs to form carbonic acid that dissociates into bicarbonate and H ions requires what enzyme

carbonic anhydrase

CO2 diffuses

across tissue membrane and into RBCs to be converted to bicarbonate

CO2 binds to Hb at the

globin chains

Chloride shift

Cl ions enter RBC and bicarbonate ions leave

At tissue capillaries

Reverse chloride shift

bicarbonate ions are pumped back into RBCs in exchange for chloride and convert back to CO2 and diffuse into alveoli

Bohr effect

as ph of blood declines, amount of O2 bound to Hb also declines

central chemoreceptors are located

medulla

At what PO2 does O2 saturation of Hb decrease more rapidly

40 mmHg and under

at PO2 of _____, hemoglobin is 98% saturated.

104 mmHg