respiration physiology Flashcards
cellular respiration
within cells oxygen breaks down glucose to generate ATP
co2 is generated and must be removed from the cell
therefore there’s gas exchange
lung structure
right:
- 3 lobes: superior, middle and inferior
- sup and mid separated by horizontal fissure and sup and inf by oblique
left:
- 2 lobes: superior and inferior
- separated by oblique fissure
- cardiac notch on superior- bottom left corner
apex at top of both
bronchial tree order
larynx
trachea
2 main bronchi
2nd bronchus
3rd bronchus
bronchiole
what’s conducting and respiratory zones
c: trachea
1st bronchus
2nd bronchus
3rd bronchus
terminal bronchiole
r: respiratory bronchiole
alveolar duct
alveolar sacs
alveoli
features of the bronchial tree
goblet cells
ciliated cells
glands
hyaline cartilage
smooth muscle
elastic fibres
goblet cells
ciliated cells
glands
hyaline cartilage
smooth muscle
elastic fibres
- produce mucus
- waft mucus back up
- secretion of mucus (along with goblet to trap particles) and serous fluid (contains enzymes to kill bacteria)
- c shaped rings around trachea to provide rigidity
- support airway structure and relax/ contract in response to airway
- allow stretching
respiratory air flow
air naturally flow from high pressure to low pressure
movement of air in/out of lungs is caused by pressure difference between:
air in mouth (atmos pressure) and air in alveoli
pressure changes in lungs (inhalation and exhalation)
I: pressure is lowered in alveoli by increasing lung volume
the pressure inside the alveoli is lower than atmshereric pressure- air enters the lungs
E: pressure is raised in alveoli by decreasing lung volume
pressure inside alveoli is higher than atmospheric pressure- air leaves lungs
movement of structures during breathing
I: rib cage expands and muscles contract and diagphram contract (increases volume of lungs and resp for 75% of the air that enters the lungs)
E: rib cage smaller and muscles relax an diaphragm relaxes
external intercostal muscles
- helps elevate the ribs and expand the thoracic cavity in inhalation
- rbs move outwards and upwards= increase volume in lungs
- respoible for 25% of air that enters lungs
accessory muscles of breathing
used during forceful breathing
INHALTION:
- sternocleidomastoid muscle: elevates sternum
- scalene muscles: elevate upper ribs
- pectoralis minor: expand rib cage by elevating the 3rd through 5th ribs
EXHALATION:
- internal intercostal muscles: bring ribs down
- transverse thoracis: pull rubs down
- abdominals and oblique: pull ribs down, compress abdominal contents- pus diaphragm up
intrapleural pressure
pressure that exists between the 2 pleural layers of the pleural cavity
always lower than atmospheric pressure
prevents natural tendency of lung to collapse
alveoli
gas exchange:
- lungs contain about 300 million alveoli
- surface area available is 70 square metres
- narrow pulmonary capillaries and thin resp membrane = rapid diffusion
structure:
type ONE: squamous cells lining the walls
type TWO: cuboidal epithelium that secrete alveolar fluid (surfactant)
gas exchange
diffusion is movement of material from high to low conc
conc of gases measured as partial pressures
greater the difference in partial pressure, greater rate of diffusion
role of surfactant in alveoli
- reduce surface tension
- increase stability
- reduce collapse likelihood
oxygen transport
o2 doesn’t dissolve in water easy
- 1.5% of the o2 inhaled dissolve in plasma
- 98% carried by haemoglobin
haemoglobin increases o2 carry capacity by 70 times
haemoglobin structure
contains iron atom that binds to oxygen
heme unit binding oxygen
pulmonary capillaries:
high partial pressure of oxygen
oxygen binds to haemoglobin
tissue capillaries:
low partial pressure of oxygen
oxygen unloaded from heme units
cooperative binding
when first oxygen binds, haemoglobin shape changes to make binding 2nd oxygen easier
in tissue, pp of oxygen is low making it harder for Hb to bind to oxygen so shape changes slightly
shape change= next binding is easier
as sites get used up, binding of oxygen is hard since its really saturated (lungs)
graph is sigmoidal as one o2 molecule make it easier for the affinity of another
factors affecting haemoglobin affinity for oxygen
acidity
pp of co2
temp
biphosphoglycerate
acidity
as ph drops, affinity of Hb for o2 decreases
- metabolically active tissues produce lactic and carbonic acid (lower ph)
- hydrogen ions bind to Hb decreasing affinity for oxygen
pp of co2
of pp of co2 rises, Hb releases o2 more readily
- co2 binds to Hb decreasing affinity for o2
- pp of co2 and pH are related- low blood ph results from high pp of co2
temp
temp increases= more o2 unloading from Hb
- in metabolically active tissues a lot of heat is released
biphosphoglycerate
BGP binds to Hb that causes o2 to be less tightly bound
- formed in rbc when they breakdown glucose to form ATP (glycolysis)
release of O2 in tissues
decreased pH
increased co2
increased temp
BGP
(all cause greater release of o2 from Hb at same pp)
uptake of o2 in alveoli
increased pH
decreased co2
lower temp
(all cause greater uptake of o2 from Hb at same pp)
co2 transport
dissolved co2 in blood plasma (10%)
as carbamino compounds bound to protein in blood majority bound to haemoglobin (30%)
bicarbonate ions in blood plasma (70%)
carbon monoxide poisoning
200 times greater affinity for Hb that o2
reduce oxygen carrying capacity of the blood
without urgent admission of pure o2, CO poisoning is fatal
