Chapter 19: Respiratory System Flashcards
breathing is also known as…
ventilation
actions responsible for breathing:
inspiration & expiration
respiratory cycle
1 inspiration & 1 expiration
what muscles are involved with inspiration?
diaphragm & external intercostals; active
what is the force that moves air into lungs?
atmospheric pressure
inspiration
- pressure & volume inversely related
- if pressure inside alveoli decreases, atmospheric pressure pushes air into airways
- occurs at resting inspiration as phrenic nerves stimulate the diaphragm to contract down
- volume of thoracic cavity increases, & pressure decreases
- air rushes into thoracic cavity in response to pressure difference
expiration
- passive
- elastic recoil of lung tissues & abdominal organs, as tissues return to original shape at end of inspiration
- surface tension that develop on moist surfaces of alveolar linings shrinks alveoli
spirometry
different degrees of effort in breathing move different volumes of air in & out of lungs
dead air spaces
air that does not reach functional alveoli
3 types of dead air spaces
- anatomic
- alveolar
- physiologic
anatomic space
space where no gas exchange occurs
alveolar space
air reaches nonfunctional alveoli
physiologic
anatomic & alveolar
minute ventilation
- volume of new atmospheric air moved into respiratory passages each minute
- tidal volume x breathing/respiratory rate
- air can fluctuate
alveolar ventilation
- tidal volume - physiologic dead space, x breathing rate
- volume of air that reaches alveoli each minute
- important value, since it impacts O2 & CO2 concentration in alveoli
sneezing
clears upper respiratory
coughing
clears lower respiratory
dorsal respiration
stimulates muscles of inspiration, mainly the diaphragm
ventral respiration
basic rhythm of breathing
pontine respiration
limits duration of each inspiration
where are the respiratory areas located?
pons & medulla oblongata
partial pressure
amount of pressure each gas contributes to total; O2 = 21%
factors affecting breathing (7)
- partial pressure
- H+ ions
- degree of lung tissue stretch
- emotional state
- level of physical activity
- chemoreceptors
- PCO2 & H+ ion conc
central chemoreceptors
- ventral part of medulla
- monitor pH of brain
- low blood PO2 does not have much effect
- H+ ions do not cross BBB
- CO2 crosses BBB & binds to H2O
- H2CO3 dissociates and releases H+
- CO2 linked to H+ concentration; due to acidity
increased CO2 =
increased alveolar ventilation
peripheral chemoreceptors
- sense changes in PO2
- in carotid and aortic
decreased PO2 =
increased BP & TV, leading to increased alveolar ventilation
inflation reflex
- helps regulate depth of breathing
- stretch receptors stimulated
- sensory impulses travel over vagus nerve
- duration of inspiratory bursts then shortened
alveoli
- microscopic air sacs
- pores may permit air to pass from one alveolus to another
respiratory membrane
- wall is simple squamous (type 1)
- some of wall is made of cells (type 2- pulmonary surfactant)
pulmonary surfactant
decrease surface tension of alveoli
alveolar wall
simple squamous
blood capillary wall
simple squamous
basement
layers join walls of alveoli & walls of capillaries
difference in partial pressure…
driving force for diffusion of O2 & CO2 across respiratory membrane
oxygen transport
2 methods; enters RBC’s or dissolved in plasma
chloride shift
as negatively charged bicarbonate ions diffuse out of RBC’s, chloride ions from plasma diffuse into cells; maintains electrical charge of RBC’s
