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Respiratory System
Human Physiology
53
Physiology
Undergraduate 4
07/20/2011

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Term
external respiration
Definition
exchange of gases between the alveoli and pulmonary capillaries
Term
internal respiration
Definition
exchange of gases between the capillaries and the cells in the tissue
Term
plueral membrane
Definition
several layers of elastic tissue and capillaries that surrounds the thorax and lungs
contains pleural fluid
decrease friction between plueral membrane
holds lungs tight against thoracic wall and stretched in a partially inflated state
Term
intrapleural pressure
Definition
subatmospheric (-3mmHg)
prevents lung collapse because it exerts a negative force on the pleural membrane
Term
airway path
Definition
oral&nasal cavity
pharynx
larynx
trachea
right and left bronchus
bronchi
bronchioles
alveoli
Term
as move down the air pathway....
Definition
increase in branching
decrease in diameter
cartilage replaced by smooth muscle
epithelium gets thinner
cilia replaced by macrophages
increase in total cross sectional area
Term
trachea and bronchi
Definition
psuedostratified ciliated columnar epithelium
cartilage-maintain open airway and can't collapse
cilia-move mucus & trapped particles to pharynx to be coughed ,sneezed, or swallowed
goblet cells produce mucus
Term
bronchioles
Definition
simple cuboidal epithelium
smooth muscle-changes airway diameter, can collapse
no cilia
Term
alveoli
Definition
site of gas exchange
3 types of cells: macrophages, type 1 alveolar cells, type 2 alveolar cells
elastic fibers inbetween to create elastic recoil when lung tissue is stretched (smooth muscle would block rapid gas exchange)
Term
type 1 alveolar cell
Definition
simple squamous epithelium
gas exchange occurs
Term
type 2 alveolar cell
Definition
secrete surfactant-->
decrease surface tension of fluid within alveoli
keeps alveoli from collapsing
increase compliance (ability of lungs to stretch)
easier to inflate alveoli
Term
surfactant
Definition
decrease surface tension of fluid within alveoli (separates membrane to increase gas exchange)
keep alveoli from collapsing
makes it easier for the alveoli to inflate following exhalation
increase compliance (ability of the lungs to stretch)
Term
respiratory membrane
Definition
alveolar wall (squamous epithelium)
capillary wall (endothelial)
with thin basement membranes for easy gas exchange
Term
compliance
Definition
how easily the lungs can be stretched
affected by-->
elasticity of lung tissue and thoracic cage
surface tension of alveoli
Term
airway resistance
Definition
poiselle's law R=(length x viscosity)/radius^4
length of system and viscosity of air usually constant
diameter of airway alters resistance
-decrease diameter=bronchoconstriction (parasympathetic or histamine)
-increase diameter=bronchodilation (sympathetic)
-physical obstruction such as mucus or other factors
Term
gas laws
Definition
gases move from areas of high P to low P
decrease in V=increase in P
Term
ventilation
Definition
movement of air between the atmosphere and the alveoli
gas movement based on changes in pressure and volume in thoracic cavity
involves inspiration and expiration
Term
inspiration
Definition
increase in atmospheric P
decrease in thoracic cavity P
contraction of muscles by somatic motor neurons
-diaphragm=lowers thoracic floor
-external intercostals=ribs up and out
air flows into lungs
Term
forced inspiration
Definition
contraction of additional muscles to increase thoracic volume/decrease thoracic pressure
-scalenes=ribs upward
-sternocleidomastoids=sternum upward
Term
expiration
Definition
decrease atmosphere P
increase lung P
relaxation of inspiratory muscles
elastic recoil of lungs
decrease in thoracic volume/increase thoracic P
air flows out of lungs
Term
forced expiration
Definition
contraction of additional muscles to decrease thoracic volume/increase thoracic pressure
-internal intercostals=ribs inward
-abdominal=ribcage inwards & abdominal organs upward
Term
tidal volume
Definition
normal breathing volume
amt air moved during a single inspiration or expiration
average=500mL
Term
inspiratory reserve volume
Definition
additional volume of air that can be inhaled after a normal inspiration
Term
expiratory reserve volume
Definition
amount of air that can be forcefully exhaled after the end of a normal expiration
Term
residual volume
Definition
amount of air left after maximum expiration
Term
vital capacity
Definition
maximum amount of air that can be moved into and out in one breath
TV+IRV+ERV
Term
inspiratory capacity
Definition
maximum amount of air that can be inspired
TV+IRV
Term
functional residual capacity
Definition
amount of air left after normal breathing
TV+ERV
Term
total lung capacity
Definition
amount of air that can be held by the lungs
TV+IRV+ERV+RV
Term
pulmonary ventilation
Definition
total amount of air that moves into and out lungs
PV=breathing rate (breaths/min) x tidal volume (mL/breath)
Term
alveolar ventilation
Definition
amount of fresh air that reaches the alveoli
not all inspired air reaches alveoli=dead space (150mL)
rate and depth of breathing affects AV
-deep breathing/slow breaths=increase in fresh air to alveoli and increase in AV
-shallow breathing/rapid breaths=decrease in fresh air to alveoli and decrease in AV (tidal volume is decreased)
*total pulmonary ventilation is not affected by changes in rate and depth of breathing. always stays the same.
*
Term
diffusion of gases
Definition
based on partial pressure gradients of gases
solubility in plasma
Term
diffusion of oxygen
Definition
alveoli PO2=100mmHg
arterial blood PO2=100mmHg
peripheral tissues PO2venous blood PO2=40mmHg
Term
diffusion of carbon dioxide
Definition
peripheral tissues PCO2 >or equal to 46mmHg
venous blood PCO2=46mmHg
alveoli PCO2=40mmHg
arterial blood=40mmHg
Term
oxygen transport
Definition
2% dissolved in plasma
98% bound to hemoglobin-->oxyhemoglobin
occurs in arterial blood
Term
oxygen-hemoglobin binding
Definition
depends on PO2 in plasma (dictate loading) and PO2 in cells (dictate unloading)
-increase O2 con.=O2 binds/loading
-decrease O2 con.=O2 released/unloading
%saturation of hemoglobin=amt of O2 bound to hemoglobin at a given PO2
Ex: (2 oxygen bound/4max O2 can be bound)x100=50% saturated hemoglobin
Term
oxygen-hemoglobin dissociation curve
Definition
x axis= resting cell PO2 mmHg
y axis= % hemoglobin saturation
less than 40mmHg=unloading
@40mmHg=75% saturation
-O2 reserve for cells that have increase in metabolism
>60mmHg=@ least 90% saturation
increase in exercise=increase in hemoglobin saturation because muscles need more oxygen to work
Term
other factors that affect oxygen-hemoglobin binding: temperature
Definition
increase temperature=decrease O2 binding
occurs during increase in metabolism
Term
other factors that affect oxygen-hemoglobin binding: PCO2
Definition
increase in PCO2=decrease in O2 binding
occurs during increase in metabolism
Term
other factors that affect oxygen-hemoglobin binding: 2,3-DPG
Definition
2,3-DPG increases in hypoxia conditions (high altitude, anemia, extended period of low oxygen)
increase in 2,3-DPG=decrease in O2 binding
Term
other factors that affect oxygen-hemoglobin binding: pH
Definition
Bohr Effect
increase in pH=increase in O2 binding
occurs during increase in metabolism
Term
carbon dioxide transport
Definition
7% dissolved in plasma
23% bound to hemoglobin-->carboxyhemoglobin
-binds to polypeptide chains
70% bicarbonate ion in plasma
-CO2+H2O+carbonic anhydrase enzyme in RBC <--> H2CO3 <--> H+ + HCO3-
occurs in venous blood
Term
chloride shift
Definition
Cl- ions enter red blood cells as HCO3- ion leaves to maintain the membrane potential
Term
hemoglobin
Definition
quaternary structure, complex protein
4 globular protein chains (2 alpha, 2 beta)
each chain has iron containing heme group
O2 binds to heme group
CO2 binds to protein chains
1 hemoglobin can bind 4 O2
Term
ventillation regulation
Definition
medulla and pons (brain stem)
-control basic rhythm of breathing
-forced breathing changes (influenced by other factors) --> emotions and voluntary control
-somatic motor neurons to inspiratory and expiratory muscles
Term
chemoreceptors
Definition
central-medulla
peripheral-carotid artery and aorta
Term
central chemoreceptors
Definition
medulla
respond to changes in plasma PCO2 (increase)
increase in CO2 and H+ in cerebrospinal fluid stimulates medulla to increase ventilation to decrease PCO2
Term
peripheral chemoreceptors
Definition
carotid artery and aorta
respond to changes in arterial plasma PCO2, PO2, H+
-increase PCO2 and H+
-decrease in PO2 (<60mmHg)
results in increase in ventilation to decrease plasma PCO2 and increase plasma PO2
Term
irritant receptors in airways
Definition
detect inhaled particles or noxious gas
signal CNS to stimulate parasympathetic bronchoconstriction
Term
hering-breur inflation reflex
Definition
prevents overinflation of lungs
if tidal volume exceeded normal volume, stretch receptors detect change
stretch receptors signal CNS-->brain stem stops inspiration
Term
cerebral dominance
Definition
limited conscious control
cannot override chemoreceptor influence
chemoreceptors respond to increase PCO2 and decreased PO2 levels and cause the brain stem to override the cerebrum in the control of breathing and increase ventilation
Term
limbic system
Definition
emotions may affect breathing rate and depth
Term
airway modification
Definition
warmed by body heat
humidify=water from mucosal lining evaporates into incoming air
cleanse=cilia, antibodies in mucus, macrophages filter out/kill foreign material so it does not reach alveoli
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