two parts of the brain stem
medulla and pons
2 parts of medulla
ventral and dorsal respiratory groups
2 parts of pons
pneumotaxic center and apneustic center
dorsal respiratory group function
drives inspiratory response; communicates w pre-motor neurons
what innervates the diaphragm?
phrenic nerve
what nerve sends info back to brain for respiratory system?
vagus nerve
bronchodilation is caused by
sympathetic nerves
bronchoconstriction is caused by
parasympathetic nerves
negative pressure allows
gases to fill pleural space
quiet inspiration =
muscle action - diaphram moves 1 cm and ribs are lifted by muscles intrathoracic pressure falls and air is inhaled
quiet expiration
passive process with no muscle action; uses elastic recoil and alveolar surface tension to pull inward and push air out
in forced breathing, which muscles inspire and which expire?
inspiration - sternocleidomastoid, scalenes, pectoralis minor exp -abdominal mm, internal intecostals
olfactory epithelium
has: bopolar neurons, supporting cells, stem cells, thin basement membrance, bowmans glands doesnt have: no goblet cells,
what muscle underlies true vocal cords?
vocalis muscle
false vs true vocal cords
false - before true ones, surface is PCC, core of serous glands true - right before trachea (after false ones), surface is stratified squamous epithelium, core = vocalis muscle
path after mouth –>
pharynx, larynx, then trachea
tracheal cartilage C rings are
in the front, back is attached by trachealis muscle - which allows esophagus to expand as food passes by
respiratory epithelium is =
pseudostratified ciliated columnar (PCC) epithelium
how to tell difference between bronchi and bronchioles?
bronchioles do NOT have cartilage
when bronchus turns into bronchiole…
cartilage disappears and then there is just smooth muscle no opening into alveoli yet fewer ciliated cells, no goblet cells new cell = CLARA cells
clara cells
bronchiolar expocrine cells with microvilli secrete surfactant , CC16 (modulates inflammation), and detox using p450 enzymes
requirements for efficient gas exchange
large area for diffusion minimal distance match ventilation and blood flow
termoinal bronchus leads to –>
lobular bronchiole –> terminal bronchiole –> respiratory bronchiole –> alveolar duct -> alveolar sac
pulmonary resistance is ____ compared to systemic resistance
low
as PO2 drops in an alveolus,
resistance in arterioles increase (perfusion to non ventilated sections!) and when alveoli is higher in Pressure than the capillaries, the air pressure can collapse the capillaries
west zones of lung pressure top, middle, bottom?
top - alveolar >arterial > venous middle: arterial > alveolar > venous bottom: arterial > venous > alveolar
type 1 vs type 2 pneumocytes
1 - squamous cells, flatter 2- larger and produce surfactant, rounder
what are alveolar cells called?
type 1 and 2 pneumocytes
type 2 alveolar cell/pneumocyte
“septal cell” secretes surfactant develops late in pregnancy premature baby —> deficient surfactant –> respiratory distress syndrome or hyaline membrane disease
dust cells
alveolar macrophages
what do alveolar macrophages do?
phagocytosis and host defense modulations
spirometry
measure how quickly you inhale , how much you exhale, and how fast you exhale
IRV FEV1 TV ERV
insiratory reserve v - max above TV amount exhaled in first second in forced exp. normal breathing volume exchanged expiratory reserve v - max expired below TV
vital capacity =
TV + IRV + ERV
residual volume
cannot be exhaled
in elastic lung, volume is directly proportional to
pressure difference across the wall
transmural pressure (Ptm) =
internal surface pressure - external surface pressure
high compliance
very distensible more vertical on P vs V chart change in pressure caused greater changes in volume
compliance =
slope (in Pvs V) changeV/change P curvilinear relationship
in inspiration, alveolar pressure ____ and pleural pressure ____
alveolar increases p pleural decreases in p increased Ptm = large increase in lung volume
direction of lungs and chest wall forces
lungs have inward force chest wall has outward force
PV curve shifts ___ in inspiration and ____ in expiration
right left
law of laplace
p = 2T/r more pressure is required to inflate smaller alveoli
why dont alveoli collapse?
surfactant reduces surface tension
surfactant is more concentrated at
smaller alveoli
emphysema vs pulmonary fibrosis
e- enlarged alveoli, loss of recoil f-increases fibrosis, increased recoil
loss of alveolar walls
dilated alveoli
emphysema
fibroblast production
collagen deposition
restrictive, pulmonary fibrosis
in emphysema, tissue cannot…
resist pull of the chest, increased compliance
high lung volume but hard to expel
in pulmonary fibrosis, tissue is…
stiff,
low lung volume, hard to get air in
where is airway resistance greatest?
middle sized artery
small has largest SA so resistanc is lowered
resistance =
change in P/flow
flow is driven by
pressure
COPD vs fibrotic lung disease
copd - decrease recoil, increase TLC and Residual volume, decreased expiratory flow
fibrosis - increase recoil, decrease TLC and residual v, increase in expiratory flow
ventral respiratory group
mostly quiescent in quiet breathing
powerful expiratory signal during exercise
influenced by cerebral cortex/emotion/stress
where central pattern generator might be?
ventral resp group
pneumotaxic center
upper pons
inspiritory inhibition off switch
stimulation shortend inspirations and increases rate
apneustic center
lower pons
depth pf breath control
if you transect above the apneustic center (lower pons), what happens?
longer inspirations and short expiration (apneustic breathing)
neurons of vrg and drg are indirectly sensitive to…
PaCO2, PaO2, and pH
central chemoreceptors
sense H+ and effector is diaphragm
peripheral chemorecepptors
sense O2, CO2, and H+ and effector is ext intercostal m (inspiration)
pulmonary receptors
sense stretch –> expiration via accessory m
joint and muscle receptors
sense stretch and tension –> int intercostals m and abdominal m
carotid body
a peripheral chemoreceptor that mainly provides afferent input to the respiratory center that is highly O2 dependent. However, the carotid body also senses increases in CO2 partial pressure and decreases in arterial pH, but to a lesser degree than for O2
type one glomus cells measure gas content directly in blood
type 2 glomus cells
support cells in carotid body
change in blood CO2 acute and chronic effects
acute - potent but then declines due to diffusion w BBB and renal adaptation
oxygen does not have a significant effect on
central receptors