WEEK 11 Flashcards
describe the concentration of oxygen in the arterial blood
- 98.5% oxygen bound to the haemoglobin
- 1.5% dissolved in plasma
describe haemoglobin x3
- four global chains each with a haem group
- haem attaches to oxygen
- binding to a haemoglobin is a reversible reaction
describe oxygen saturation x4
- when all four haems are attached= 100% saturation
- saturation depends on partial pressure of oxygen and haemoglobin binds to oxygen
- after binding to the first oxygen, haemoglobin changes to shape to facilitate further o2 uptake
- oxygen affinity is increased
what is the effect of PH on oxygen affinity and dissociation
- decreased ph means there is lower oxygen b binding affinity
- increased ph this means there is higher oxygen binding affinity
what is the effect of temp on haemoglobin affinity and dissociation
- increased temp= lower oxygen binding affinity
- decreased temp= higher oxygen binding affinity
effect significant in active tissues generating large amounts in heat
describe transport of carbon dioxide ( x3)
- 70% carried as a bicarbonate
- 23% bound to haemoglobin
-7% dissolved in plasma
define hypercapnia
- describe the main causes of hypercapnia (x2)
- describe the consequences (x3)
def= blood PCO2 > 45mmHg
main causes:
- hypoventilation- inadequate oxygen delivery and carbon dioxide removal
- lung disease- decreased gas exchange
consequences:
- respiratory acidosis
- decreases central nervous system activity
- lethargy, coma and death
hypocapnia defintion, what is the main cause and consequence
def= blood PCO2< 40mmHg
causes:
- hyperventilation= increased carbon dioxide removal
consequences;
- respiratory alkalosis
- increased central nervous system
- ‘pins and needles’ and dizziness
what is a spirometry
lung function test
- air is measured in terms of lung volumes and lung capacities
define volume
measures of the amount of air for one function
define capacity
two or more values
define tidal volume
amount of air inhaled during a normal breath
define expiratory reserve volume
amount of air that can be exhaled after normal inhalation
inspiratory reserve volume defintion
amount of air that can be further inhaled after a normal inhalation
define residual volume
air left in the lungs after a forced exhalation
define vital capacity
maximum amount of air that can be moved in or out of the lungs in a single respiratory cycle
define inspiratory capacity
volume of air that can be inhaled in addition to a normal exhalation
define functional residual capacity
volume of air remaining after a normal exhalation
define total lung capacity
total volume of air in the lungs after a maximal inspiration
define forced expiration volume
how much air can be forced out of the lungs over a specific time period, usually one second
define respiratory minute volume and how can it be calculated
defined as the total amount of air moving into respiratory passage each minute.
- tidal volume x breathing rate
what is the calculation of alveolar ventilation
tidal volume- anatomic dead space x breathing rate
define respiratory work
energy cost of breathing- at rest less than 5% of total energy expenditure
what are the 3 factors affecting airflow
1) diameter of airways= autonomic nervous system control
2) airflow during inspiration vs expiration
3) turbulent vs laminar flow
autonomic system control of the bronchiole diameter
1) parasympathetic nervous system:
- cranial nerve
- neurotransmitters
- acetylcholine
- result= bronchiole smooth muscle contraction> broncho constriction
2) sympathetic nervous system- no direct control :
- stimulates adrenal medulla to release
- noradrenaline + adrenaline
- result= bronchodilation
resistance and flow during normal ventilation ( inspiration and expiration)
during inspiration:
- positive pressure in airways increases the diameter of the lumen
- decreased resistance and increased flow through
during expiration:
- lower pressure in airways decreased diameter of the lumen
- increased resistance and decreased flow occurs
what are the 3 respiratory centres
1) dorsal respiratory group:
- medulla
- mainly inspiration
2) ventral respiratory group:
- medulla
- mainly expiration
3) pneumotaxic centre:
- pons
- mainly controls the rate and depth of breathing
describe chemoreceptors ( peripheral and central)
peripheral:
- located at the aortic and carotid bodies
- stimulation of the dorsal respiratory group
- monitor the composition of arterial blood
- stimulated by lack of oxygen
central:
- located in the medulla oblongata
- monitor the composition of the CSF
- increases carbon dioxide in blood
describe baroreceptors
- respiratory rate increases with low blood pressure
- respiratory rate decreases with high blood pressure
describe mechanoreceptors x4
- detect stretch in the lungs
- stretched lungs overexpand
- reflex terminate inspiration
- decreased tidal volume with increased breathing rate
