Respiratory System 2

Question 1

what is daltons law of partial pressures?

Answer 1

• air we breathe made of n2, o2, h2o, co2
• there = diff % of each gas in air
• each gas makes up diff proportion of total mixture
• sum of pp = total pressure of air
• pp of various gases = imp in establishing gradients which drives gases through system

Question 2

how is the pCO2 in peripheral tissues higher than in arteries returning from lungs?

Answer 2

CO2 = end product of cellular respiration

Question 3

how is the pO2 lower in tissues than in arterial blood?

Answer 3

O2 continuously used by cells

Question 4

what are the gradients of o2 and co2?

Answer 4

o2 - from blood to tissues

co2 - from tissue to blood

Question 5

following internal respiration, what happens to o2 and co2?

Answer 5

o2 unloads to tissues

co2 uptake into blood

po2 in venous blood dec to 40 mmHg

pco2 in venous blood inc to 45mmHg

Question 6

following ventilation, what happens to o2, co2?

Answer 6

po2 in alveoli inc

pco2 dec

Question 7

what are the pressure gradients of o2 and co2?

Answer 7

o2 - lungs to blood

co2 - blood - lungs

Question 8

what is a Hb mol composed of?

Answer 8

4 globin chains surrounding central haem group

2 alpha + 2 beta chains

4 o2 per Hb

Question 9

saturated haemoglobin

Answer 9

when all 4 haems of mol bound to oxygen

Question 10

partially saturated haemoglobin

Answer 10

when 1 to 3 haems bound to oxygen

Question 11

the rate that haemoglobin binds + releases oxygen is regulated by …

Answer 11

• po2
• temp of blood
• pco2
• conc of BPG (2,3-bisphosphoglycerate)

Question 12

in haemoglobin saturation, what happens if oxygen levels drop?

Answer 12

• more oxygen dissociates from haemoglobin + is used by cells
• resp rate / cardiac output don’t inc

Question 13

co2 is transported in the blood in 3 forms

what are these?

Answer 13

• dissolved in plasma
• chemically bound to proteins
• bicarbonate ions in plasma

Question 14

describe internal respiration at tissues using (formula)?

Answer 14

• co2 diffuses into RBC
• high conc of co2 equation to shift to right
• combines with water to = carbonic acid
• h2co3 dissociated into h+ + hco3-
• hydrogen ions attach to one of 4 haem mol knocking off one o2
• o2 travels down conc gradient to tissues

Question 15

what is the chloride shift?

Answer 15

counterbalances the out rush of neg bicarbonate ions from RBCs

cl- ions move from plasma into erythrocytes

Question 16

describe external respiration using (formula)?

Answer 16

• reaction shifts to left
• bicarbonate ions move into RBC + bind with h+ to make carbonic acid
• carbonic acid split into co2 + h20
• co2 levels rise
• co2 diffuses from blood into alveoli along conc gradient

Question 17

what other factors can influence haemoglobin saturation?

Answer 17

• inc in temp, h+, pco2, BPG —> inc o2 uploading from haemoglobin
  curve SHIFTS RIGHT

dec in these will shift curve left

Question 18

dorsal respiratory group / inspiratory centre

Answer 18

• located near root of nerve IX
• excites inspiratory muscles + sets eupnoea
• becomes dormant during expiration

Question 19

what is the ventral respiratory group (VRG) involved in?

Answer 19

forced inspiration + expiration

Question 20

what is depth of breathing determined by?

Answer 20

how actively respiratory centre stimulates respiratory muscles

Question 21

what is rate of breathing determined by?

Answer 21

how long inspiratory centre = active

Question 22

pulmonary irritant reflexes

Answer 22

irritants promote reflexive constriction of air passages

Question 23

inflation reflex (hering-breuer)

Answer 23

stretch receptors in lungs stimulated by lung inflation

Question 24

upon inflation, what happens?

Answer 24

inhibitory signals sent to medullary inspiration centre to end inhalation + allow expiration

Question 25

hypothalamic controls act through ...

Answer 25

limbic system to modify rate + depth of respiration

Question 26

rise in body temp acts to ….

Answer 26

inc resp rate

Question 27

cortical controls are ...

Answer 27

direct signals from cerebral motor cortex that bypass medullary controls

Question 28

changing pco2 levels are monitored by ...

Answer 28

central chemoreceptors of brain stem co2 in blood diffuses into cerebrospinal fluid

Question 29

what does hypercapnia result in (inc in pco2)?

Answer 29

- inc in h+ conc in medulla - stimulates DRG to inc depth + rate of breathing - allows body to remove co2

Question 30

depth + rate of breathing : pco2 process

Answer 30

- inc in arterial pco2 - dec ph in cerebrospinal fluid - central chemo receptors in medulla mediate response —> afferent impulses —> medulla respiratory centres —> efferent impulses —> respiratory muscles inc ventilation arterial pco2, ph return to normal

Question 31

what is the arch of the aorta?

Answer 31

main vessel originating from heart

Question 32

what is the carotid sinus?

Answer 32

main artery of neck

Question 33

where are the peripheral chemoreceptors located ?

Answer 33

- arch of aorta | - carotid sinus

Question 34

decrease in po2 will stimulate DRG to...

Answer 34

inc resp rate

Question 35

hypoventilation occurs when...

Answer 35

pco2 levels = abnormally low body slows resp rate

Question 36

what is a simple way to overcome hypoventilation?

Answer 36

holding breath/breathing slow and shallow will cause co2 levels to rise in blood as co2 levels rise, chemoreceptors triggered to stimulate DRG to inc ventilation

Question 37

what may occur until pco2 levels rise?

Answer 37

apnoea (breathing cessation)

Question 38

hyperventilation occurs when ...

Answer 38

co2 removed from blood quickly occurs in response to hyercapnia (high co2 in blood) regulated by h+ conc in brain

Question 39

what does hyperventilation reduce?

Answer 39

H+ (acid)

Question 40

hypoventilation pushes reaction to ...

Answer 40

right

Question 41

respiratory alkalosis has a ph of ..

Answer 41

> 7.35

Question 42

what are arterial oxygen levels monitored by?

Answer 42

aortic + carotid bodies

Question 43

what is a hypoxic drive?

Answer 43

when po2 levels become principle respiratory stimulus

Question 44

what are the causes of hypoxia?

Answer 44

reduced levels of oxygen in blood

Question 45

hypoxic hypoxia

Answer 45

due to not enough pulmonary gas exchange - high altitudes, drowning, aspiration, CO poisoning etc

Question 46

ischaemic hypoxia

Answer 46

inadequate circulation - diabetes mellitus, atherosclerosis

Question 47

anaemic hypoxia

Answer 47

anaemia - diet, internal bleed

Question 48

histotoxic hypoxia

Answer 48

metabolic poison cyanid poisoning

Question 49

what are the signs of cyanosis?

Answer 49

- blueness of skin, lips, finger nail clubbing

Question 50

quick travel to altitudes above 8000 feet may produce symptoms of acute mountain sickness give eg of some symptoms?

Answer 50

- headaches - shortness of breath - nausea - dizziness

Question 51

how does acclimatisation to high altitudes occur?

Answer 51

chemoreceptors = more responsive to pco2 when po2 declines decline in blood o2, stimulates kidneys to acerbate prod of EPO (erythropoietin)

Question 52

what are common features of homeostatic imbalance?

Answer 52

- COPD - history of smoking - dyspnoea (laboured breathing) - coughing + frequent pulmonary infections - hypoventilation with respiratory acidosis

Question 53

what is emphysema?

Answer 53

destruction of alveolar walls, loss of lung elasticity, air trapping