Respiratory Zone

major structures of respiratory system

nose, pharynx, larynx, trachea, bronchial tree, lungs

cardio system and resp system cooperate to supply body cells with ____ and to eliminate ___

O2, CO2

resp system provides for ___

gas exchange

cardio system transports ____

respiratory gases

when there is a lack of oxygen, ____

rapid death of cells from O2 starvation and buildup of waste products

3 basic steps of respiration

ventilation (breathing), external (pulmonary) respiration, internal (tissue) respiration

upper resp system consists of ____

nose, pharynx, associated structures

lower resp system consists of ____

larynx, trachea, bronchi, lungs

conducting zone

moves air to lungs

pathway of conducting zone

nose, pharynx, larynx, trachea, bronchi, bronchioles, terminal bronchioles

respiratory zone

main site of gas exchange

pathway of resp zone

respiratory bronchioles, alveolar ducts, alveolar sacs, alveoli

alveolar sac

2 or more alveoli sharing a common opening

actual site of gas exchange in lungs

across alveoli walls

2 types of alveolar epithelial cells

type I - main site of gas exchange, type II - secrete alveolar fluid (surfactant - reduces tendency of sacs to collapse)

respiratory membrane structure

alveolar epithelial wall of type I cells, alveolar epithelial basement membrane, endothelial cells of capillary, capillary basement membrane (first 2 layers from alveoli, second 2 layers from capillary)

lungs contain about ____ alveoli

300 million

total alveolar surface area equivalent to ____

1/2 tennis court

pulmonary ventilation

step 1 of respiration - inspiration and expiration (Boyle's law), respiratory muscles, lung volumes. inhalation and exhalation, exchange of air between air and alveoli

external respiration

step 2 of respiration - Dalton's Law, Henry's Law. exchange of gases between alveoli and blood

internal respiration

step 3 of respiration - rate of gas exchange, O2 and CO2 transport, hemoglobin, regulation, exchange gases between systemic capillaries and tissue cells, supplies cellular respiration to make ATP

equal air pressure before inhalation

~760 mm Hg

air moves down in ____

pressure gradient

pressures ____ as size of container holding set amount decreases

increases

Boyle's Law

movement of air into and out of lungs, pressure of a gas in a closed container is inversely proportional to the volume of the container

first step of inhalation/inspiration

contraction of diaphragm - most important muscle in inhalation, flattens, lowering dome, responsible for 75% of air entering lungs. contraction of intercostals - contraction elevates ribs, responsible for 25% of air entering lungs.

contraction of diaphragm and intercostals causes ____

thoracic cavity to expand. parietal pleura lining expands, visceral pleura tightly adhered to parietal pleura is pulled along which pulls lungs open.

as lung volume increases, _____ pressure drops

alveolar/intrapulmonic

accessory muscles aiding inhalation during exercise or forced ventilation

sternocleidomastoids, scalene muscles, pectoralis minor

after inhalation, pressure is ____ in the lungs than in atmospheric pressure

greater

exhalation is normally ____

passive

exhalation process

elastic recoil of chest wall and lungs bring back to original shape, diaphragm relaxes and returns to dome shape, external intercostals relax and ribs drop down, only active during forceful breathing

forced exhalation

active, as opposed to passive for quiet exhalation

forced exhalation occurs during ____

exercise or playing wind instrument

muscles that contract during forced exhalation

abdominal wall muscles - moves inferior ribs down and compresses abdominal viscera forcing diaphragm, internal intercostals - pull all ribs downward

minute ventilation (MV)

total volume of air inhaled and exhaled each minute, normal adult - 12 breaths per min

tidal volume (TV)

amount of air in one breath - about 500 ml

MV = ____

12 breaths per min times 500 ml/breath = 6 liters or 6000 ml per min

only about ___% of tidal volume reaches respiratory zone

70

___% of tidal volume remains in _____

30, conducting zone

conducting zone is considered ___

anatomic (respiratory) dead space because air in these regions does not undergo respiratory gas exchange

spirogram

lung volume chart

spirometer

measurement of lung volume

inspiratory reserve volume (IRV)

taking a very deep breath, additional 1900 ml female, 3100 ml male

inspiratory capacity (IC) =

TV + IRV, 2400 ml female, 3600 ml male

expiratory reserve volume (ERV)

inhale normally and exhale forcefully, additional 700 ml female, 1200 ml male

residual volume (RV)

air remaining after ERV exhaled

funcional residual capacity (FRC) =

RV + ERV, air remaining after passive exhale

vital capacity (VC) =

IC + ERV, maximum air exhaled after maximum inhalation

total lung capacity (TLC) =

VC + RV

external (pulmonary) respiration

exchange of gases between aveoli and blood

external respiration occurs ___

by passive diffusion following rules of Dalton's and Henry's laws

Dalton's law

governs movement of gas down pressure gradients

Henry's law

explains how solubility of a gas effects its diffusion

external respiration in lungs - oxygen

O2 diffuses from alveolar air (PO2 105 mmHg) into blood of pulmonary capillaires (PO2 40 mmHg), diffusion continues until PO2 of pulmonary capillary blood matches PO2 of alveolar air

external respiration in lungs - carbon dioxide

CO2 diffuses from deoxygenated blood in pulmonary capillaries (PCO2 45mmHg) into alveolar air (PO2 40mmHg), continues until PCO2 blood reaches 40 mmHg

internal respiration

exchange of gases between capillaries and cells

internal respiration - oxygen

oxygen diffuses from systemic capillary blood (PO2 100mmHg) into tissue cells (PO2 40mmHg), cells constantly use oxygen to make ATP

internal respiration - carbon dioxide

CO2 diffuses from tissue cells (PCO2 45mmHg) into systemic capillaries (PCO2 40mmHg), cells constantly make carbon dioxide as a by-product of cellular respiration

4 effects on rate of pulmonary and systemic gas exchange

1. partial pressures of gases, 2) surface area available for gas exchange (alveoli, RBC), 3) diffusion distance (respiratory membrane very thin, capillaries), 4) molecular weight MW and solubility of gases (lower MW diffuses faster, solubility varies)

___% oxygen dissolved in plasma

1.5

___% oxygen bound to hemoglobin (Hb)

98.5

heme

non-protein cluster of atoms with an iron atom at the center

each iron atom can bind one ___ molecule

O2

oxyhemoglobin

oxygen bound hemoglobin

deoxyhemoglobin

without oxygen bound hemoglobin

Hb has a cooperative affinity for ____

O2

binding of one ___ to a heme group causes a ___ change that makes binding of other ___ molecules easier

O2, shape, O2

the higer the ___, the more easily O2 combines with ___

PO2, Hb

percent saturation expresses ___

percent of Hb-O2 compared to deoxyhemoglobin

O2 must be present in ___ to be absorbed by ___ cells

plasma, tissue

Bohr effect

factors that effect PO2 saturation - pH, PCO2, temperature

pH effect on O2 saturation

as acidity increases, affinity of Hb for oxygen decreases

PCO2 effect of O2 saturation

as PCO2 rises, Bh unloads oxygen more easily, low blood pH can result from high PCO2

temperature effect on O2 saturation

within limits, as temp increases, more O2 is released from Hb, during hypothermia more oxygen remains bound

fetal Hb

higher affinity for oxygen than adult Hb, can carry up to 30% more O2

dissolved CO2 accounts for ___% of CO2 in blood

7

bicarbonate ions

70% of CO2 transported in plasma as HCO3 (bicarbonate)

carbonic anhydrase

enzyme that forms carbonic acit from water and CO2

carbamino compounds

about 23% of CO2 combines with amino acids of plasma proteins including Hb

mechanisms to ensure respiration control

muscle contraction that regulate thorax size controlled by clusters of neurons in the brainstem, respiratory system (neurons located in medulla and pons)

3 groups of respiratory center

1. medullary rythmicity area (medulla)

2. pneumotaxic area (pons)

3. apneustic area (pons)

pneumotaxic area of respiratory center

coordinates the transition between inhalation and exhalation. inhibits inspiration to prevent over inflation

apneustic area of respiratory center

also coordinates between inhalation and exhalation. stimulates inspiratory area, causes long deep inspiration, signals from pneumotaxic area overrides apneustic area stimulation

inputs into regulation of respiratory center

1. cortical influences

2. chemoreceptor regulation

3. proprioceptor stimulation

4. inflation reflex

cortical influences

cerebral cortex allows some conscious control of respiration, breath holding limited by overriding stimuli of increased H+ and CO2, if fainting occurs from breath holding regular breathing occurs when consciousness is lost

chemoreceptor regulation

central chemoreceptors are CNS receptors in medulla, (monitor levels of CO2 and H+), peripheral chemoreceptors in walls of aorta arch and carotid arteries (monitor levels of O2, CO2, H+), hypercapnia or hypoxia stimulate inspiration area

hypoxia

deficiency of O2 at tissue level

hypercapnia (hypercarbia)

arterial blood PCO2 above 40mmHg

hypocapnia (hypocarbia)

arterial blood PCO2 below 40mmHg

proprioceptor stimulation

proprioceptors of joints and muscles activate inspiratory area to increase ventilation

inflation reflex

stretch-sensitive receptors on walls of bronchi and bronchioles, detect over-inflation of lungs

other influences to respiration

limbic system stimulation (anticipation of activity or emotions), blood pressure, temp, pain, irritation of airways