IU PHYSIOLOGY 225 EXAM 4

pulmonary circulation overview

exchange of oxygen & carbon dioxide

what is the result of diffusive lung diseases?

results in improper gas exchange across alveoli

diffusive lung diseases: _____ pCO2

⬆️

diffusive lung diseases: _____ pH

⬇️

how does the heart compensate for diffusive lung diseases?

increasing HR & CO

examples of diffusive lung diseases

smoking, membrane thickening (pulmonary edema), alveoli destruction

what affect does excess CO2 have on blood pH

pH ⬇️, becomes more acidic

gas diffuses down gradients with _____ partial pressure to _____ partial pressure

high, low

what 2 things make diffusion between alveoli & blood rapid?

1) small diffusion barrier (thin membrane)

2) large surface area

_____ moves from alveoli to blood at the same rate it is _____ by cells

O2, consumed

_____ moves from blood to alveoli at the same rate it is _____ by cells

CO2, produced

atmospheric air: PO2 & PCO2 values?

-PO2 = 160 mm Hg

-PCO2 = 0.3 mm Hg

PO2 systemic arteries, veins & cell values

-arteries = 100 mmHg

-veins = 40 mmHg

-cells = ≤ 40 mmHg

diffusive lung diseases: _____ pO2

⬇️

in PO2, oxygen diffuse from _____ to _____

blood, cells

PCO2 systemic arteries, veins & cell values

-arteries = 40 mmHg

-veins = 46 mmHg

-cells = ≥ 46 mmHg

in PCO2, carbon dioxide diffuses from _____ to ______

cells, blood

PCO2 partial pressure is _____ in various sites in the body compared to atmospheric air

higher

determinants of alveolar PO2 & PCO2

-rate of alveolar ventilation relative to the rate of O2 use & CO2 production

-PO2 & PCO2 of inspired air

-minute alveolar ventilation

-rates at which respiring tissues use O2 & produce CO2

what effect does elevation have on partial pressure?

lower partial pressure of O2 & CO2

hyperpnea

increased ventilation due to increased demand

hypoventilation

ventilation does not exceed demands

hyperventilation

ventilation exceeds demands

what kind of blood does pulmonary veins carry?

oxygenated blood

why does O2 have to be transported by hemoglobin?

it is not very soluble in plasma

in arterial blood, hemoglobin is _____% saturated

98.5%

in venous blood, hemoglobin is _____% saturated

75%

when the environment has a high PO2 where does hemoglobin bind to?

binds very tightly to oxygen

when PO2 decreases, hemoglobin tends to _____ oxygen.

release

when the environment is _____, hemoglobin tends to release more oxygen.

acidic

when the environment contains more _____, hemoglobin releases more oxygen.

carbon dioxide (CO2)

what is saturation of hemoglobin a measure of?

how much oxygen is bound to hemoglobin

what does 100% saturation indicate?

all 4 binding sites on hemoglobin have oxygen bound to them

what parameters cause a right shift on the hemoglobin-oxygen dissociation curve?

-increased temp

-increased acidity (decrease in pH)

-increase in CO2

-increase in 2-3-DPG (diphosphoglycerate)

2-3 diphosphoglycerate

produced in RBC under conditions of low O2 (anemia & high altitude), decreases affinity of hemoglobin for O2 (enhancing O2 unloading)

affinity

attraction

what does a right shift on the hemoglobin-oxygen dissociation curve allow for?

allows for more oxygen to drop @ tissues (hemoglobin has less affinity)

what kind of shift would an increase in affinity have?

left shift

what effect does carbon monoxide have on hemoglobin & oxygen relationship?

hemoglobin has greater affinity for carbon monoxide (CO) than for O2, which prevents O2 from binding to hemoglobin

which is more soluble in water & blood: CO2 or O2?

CO2

carbon dioxide transport in the blood

-about 5%: dissolved in blood

-about 5-8%: attached to hemoglobin

-86-90%: reacted with water, transported as bicarbonate

CO2 + H20 ⬅️➡️ _____ ⬅️➡️HCO3 + H+

H2CO3

respiratory system functions

-respiration

-short term adjustment of pH

-vocalization

-defense against infection

-water & heat loss

-plasma proteins activation

respiration function

-obtain oxygen (supports ATP production in the mitochondria)

-rid the body of carbon dioxide (CO2 & H2O react to form HCO3 & H+)

breathing more slowly has what effect on pH?

decreases pH

breathing more rapidly has what effect on pH?

increases pH

3 separate respiration functions ~ 1) ventilation

mechanical process of breathing

3 separate respiration functions ~ 2) gas exchange (external respiration)

-between air & capillaries in the lungs

-between systemic capillaries & tissues of the body

3 separate respiration functions ~ 3) O2 utilization

cellular respiration (internal)

the pharynx is a shared passageway for what 2 things?

food & air

larynx 2 functions

-part of the conducting zone

-pulled superiorly toward the epiglottis during swallowing to prevent substances from entering the airway during swallowing

3 conducting zone functions

-vocalization in larynx & for conducting air to the trachea

-increases air temp to body temp

-humidifies air

epithelium of the conducting zone characteristics

-goblet cells secrete mucus

-cilia move particles toward mouth

-mucus escalator

the respiratory zone acts as a region of what?

region of gas exchange between air & blood (includes respiratory bronchioles & alveolar sacs)

alveoli are sites of _____. 300 million alveoli in the lungs.

gas exchange

do alveoli have a rich blood supply? if so, how?

yes because capillaries form sheet over alveoli

what do type I alveolar cells make up?

the wall of alveoli (single layer of epithelial cells)

what do type II alveolar cells secrete?

surfactant

surfactant

a chemical made by the alveoli that acts as a detergent & reduces surface tension

what is the effect of the walls of the alveoli being lined with water?

water tends to hydrogen bond with itself so they result is a strong tendency for the alveoli to collapse

alveolar macrophages 2 functions

-defend against infection

-increases rate of diffusion across the membrane

thoracic cavity structures ~ chest wall

airtight, surrounded by bones, protects lungs

*includes internal & external intercostals, diaphragm

thoracic cavity structures ~ pleura

membrane lining of lungs & chest wall

what is around each lung?

pleural sac

intrapleural space is filled with _____ _____.

intrapleural fluid

air moves in & out of lungs by _____ flow.

bulk

what 2 things does exchange of gases at the alveoli depend on?

diffusion & favorable concentration gradients

inspiration

pressure in lungs is LESS than the atmospheric pressure

expiration

pressure in lungs is MORE than the atmospheric pressure

the difference between what 2 pulmonary pressures drive ventilation (air flow into and out of the lungs)?

the difference between atmospheric & intra-alveolar pressures

atmospheric pressure (Patm) characteristics

-other lung pressures are given relative to this

-760 mmHg @ sea level

-decreases as altitude increases

-increases under water

intra-alveolar pressure (Palv) characteristics

-pressure of air in alveoli

-varies with phases of respiration

-inspiration = negative

-expiration = positive

intrapleural pressure (Pip) characteristics

-pressure inside pleural sac (always negative & less than Palv)

-varies with phases of respiration (-4 mmHg @ rest)

-negative due to elasticity in lungs & chest wall

-loss of this results in Pneumothorax

elasticity in lungs & chest wall

-lungs recoil inward as chest wall recoils outward

-opposing forces pull on intrapleural space

-surface tension of intrapleural fluid prevents wall & lungs from pulling apart

how do you calculate transpulmonary pressure?

Palv - Pip

transpulmonary pressure characteristics

-distending pressure across the lung wall

-increase in this increases distending pressure across lungs, causes lungs (alveoli) to expand which increases volume

what pressure remains constant during the breathing cycle?

atmospheric pressure

mechanics of breathing ~ alveolar pressure

-can change alveolar pressure by changing its volume

-alveolar pressure changes affect gradients

inspiration process

-diaphragm contracts

-volume in thoracic cavity increases

-pressure in thoracic cavity decreases

-air from environment rushes in

-engaged muscles: pectoralis minor & external intercostal muscles

expiration process

-diaphragm relaxes

-volume in thoracic cavity decreases

-pressure in thoracic cavity increases

-air is forced out

-engaged muscles: abdominal & internal intercostal muscles

as the volume of the lung increases, what is the impact on atmospheric pressure?

no change

medulla & pons ~ respiratory control center process

-determine normal breathing rhythm

-neurons descend the spinal cord & stimulate other neurons which leave the spinal cord & stimulate the diaphragm/intercostal muscles

-also receives sensory input from neurons in the thoracic cavity that monitor the stretch of the lungs & chest

primary control: generation of the breathing rhythm in the brainstem

pH of the CSF

secondary control: generation of the breathing rhythm in the brainstem

carotid bodies (chemoreceptors) detect pH, oxygen & carbon dioxide levels

the cerebrum & hypothalamus provide what type of input for breathing rhythm?

emotional input

respiratory rhythm

regular repeating pattern of neural activity, generated by central pattern generator

control of ventilation by central chemoreceptors (brain): are located where?

in the medulla oblongata

control of ventilation by central chemoreceptors (brain): what changes the activity of receptor?

increased or decreased systemic arterial PCO2

control of ventilation by central chemoreceptors (brain): what directly stimulates these receptors?

CSF H+

control of ventilation by central chemoreceptors (brain): what is the main drive for ventilation/increase in respiratory rate?

increase in CO2 on the central chemoreceptors

control of ventilation by central chemoreceptors (brain): no central _____ receptors.

PO2

process example: central receptors detect a decrease in pH

1) respiratory center signals motor neurons to increase firing rate

2) diaphragm contracts more deeply & frequently

3) as lungs blow off more CO2, the pH of body fluids increase

control of ventilation by peripheral chemoreceptors: are located where?

in the carotid & aortic arteries

control of ventilation by peripheral chemoreceptors: is stimulated by a dramatic decrease in what?

systemic arterial PO2 (not a primary factor in activation)

control of ventilation by peripheral chemoreceptors: what 3 things stimulate/activate these receptors?

-increased H+

-severe decrease in O2

-increase in arterial PCO2

what is the ventilation-perfusion ratio in a normal, healthy lung?

1

ventilation (v)

rate of air flow to the alveoli

perfusion

rate of blood flow

if ventilation decreases, V/Q is _____ _____ 1. if perfusion decreases, V/Q is _____ _____ 1.

less than, greater than

low V/Q ratio (shunt) characteristics

-no ventilation of an alveolus, but perfusion remains the same

-mismatch of ventilation & perfusion