Chemical Confrol Of Resp

Question 1

What is negative feedback

Answer 1

Primary type homeostasis
Opposes initial change
Components - sensor, control centre and effector

Question 2

What are the controlled variables of RESP integrative feedback

Answer 2

Arterial Po2 (decreases)
Arterial Pco2 (increases) 
Arterial hydrogen ion conc (increases)

Question 3

What are the sensors for RESP negative feedback

Answer 3

Chemoreceptors (peripheral and central)

Question 4

What is the conflict centre for RESP negative feedback

Answer 4

RESP centres

Question 5

What are the effectors for RESP negative feedback

Answer 5

RESP muscles leading to changes in ventilation

Question 6

What is chemical control of RESP

Answer 6

Example negative feedback
Controlled variables are blood gas tensions especially carbon dioxide
Chemo receps sense values of gas tensions

Question 7

Where are peripheral chemoreceptors

Answer 7

Carotid and aortic bodies

Question 8

What doe Peripheral chemoreceptors do

Answer 8

Sense tension of oxygen and carbon dioxide and hydrogen ion in the blood

Question 9

Where are the central chemoreceptors

Answer 9

Near surface of medulla of brain stem

Question 10

What DIT he central chemoreceps do

Answer 10

Respond to the hydrogen ion conc of the CSF

Question 11

Hero is the Csf sep form blood

Answer 11

By blood brain barrier
Relatively Imperm to hydrogen ion conc and bicarbonate
Carbon dioxide diffuses readily

Question 12

How does CSF differ to blood

Answer 12

CSF has less protiens than blood and hence less buffered than blood

Question 13

What is hypercapnia

Answer 13

Increased arterial Pco2

Lead to co2 generated hydrogen ion through central chemoreceptors

Question 14

What is hypoxia

Answer 14

Decreased arterial Po2 and ventilation
Effect via peripheral chemoreceps
Stim only when arterial po2 below 0.8 kPa
Imp at high altitudes and pt’s with chronic carbon dioxide retention

Question 15

Hypoxia at high altitudes is caused by

Answer 15

Decreased partial pressure of inspired oxygen PiO2

Question 16

What is the response to hypoxia at high altitudes

Answer 16

Hyperventilation and increased cardiac output

Symptoms - headache, sickness, dizzy, nausea, shortness breath

Question 17

What are some chronic adaptations to high altitudes hypoxia

Answer 17

Increase RBC prod
Increase 2,3- BPG produced in RBC (increase oxygen offload)
Increase num caps
Increased num mito
Kidneys conserve acid (decrease arterial pH)

Question 18

What sit he hydrogen ion drive of respiration

Answer 18

Effect via peripheral chemoreceps
H+ doesn’t readily cross blood Brian barrier but carbon dioxide does
Peripheral chemoreceps help control acidosis by add non carbonic acid h+ to blood
Stimulation of H+ causes hypervent and increased elim carbon dioxide

Question 19

What are some neural and chemical factors that may increase ventilation during exercise

Answer 19

Reflexes originating form body movement 
Adrenaline release
Impulses form cerebral cortex 
Increase body temp 
Accumulation carbon dioxide and hydrogen ion generated by active muscles

Question 20

What is homeostasis

Answer 20

Maintain body internal enviro must be maintained in a morrow range 
Eg
- ph
- temp 
- conc of nutrients 
- conc of oxygen and carbon dioxide 
- conc waste prods