homeostasis

Question 1

def homeostasis

Answer 1

the maintenance of a constant internal environment within an organism as survival is dependent on maintaining an optimum internal environment

Question 2

why impt to maintain a constant internal environment

Answer 2

• provides optimum conditions for organisms to live and reproduce efficiently (pH)
• func independently from external env

Question 3

def negative feedback

Answer 3

brings detected change back to normal level, prevents overcorrection of homeostatic mechanism by signaling receptor

Question 4

diff btw endocrine system and nervous system

Answer 4

gradual vs faster
chem signals (hormones) vs electrical signals (nerves)
less localised vs usually localised
modified by learning from previous experiences vs inability to learn

Question 5

normal blood glucose level

Answer 5

90mg/100cm3 of blood

Question 6

func of insulin (3)

Answer 6

• incr permeability of cells to glucose into tissues
• incr oxidation of glucose (cellular resp)
• suppresses prod of glucagon

Question 7

when bgc decr (3)

Answer 7

1. alpha cells of pancreas stimulated to release glucagon into blood
2. liver breaks down glycogen and releases glucose into blood
3. blood glucose rises to set point, stimulus for glucagon release diminishes

Question 8

when bgc incr (3)

Answer 8

1. beta cells of pancreas stimulated to release insulin into blood
2. body cells take up more glucose
3. bgc level declines to set point, stimulus for insulin release diminishes

Question 9

func of glucagon (3)

Answer 9

• reduced permeability of glucose into tissues
• stims breakdown of glycogen into glucose in liver and skeletal muscles
• suppresses insulin prod

Question 10

func of adh (2)

Answer 10

• incr permeability of dct and collecting duct to water

- more water reabsorbed back into bloodstream via peritubular capillaries

Question 11

when wp incr (4)

Answer 11

1. osmoregulators in hypothalamus detects incr
2. pituitary gland releases less adh
3. kidney tubules reabsorbs less water into bloodstream
4. wp of blood decr

Question 12

when wp decr (4)

Answer 12

1. osmoregulators in hypothalamus detects decr
2. pituitary gland releases more adh
3. kidney tubules reabsorbs more water into bloodstream
4. wp of blood incr

Question 13

when temp incr (4)

Answer 13

1. arterioles vasodilate, shunt vessels constrict (more blood to skin capillaries, more heat removed by conduction, convection, radiation)
2. sweat glands become more active, more sweat produced, incr evap of water. removes latent heat of vapourisation
3. hair erector muscles relax, hair flat, less air/heat trapped
4. decr rate of metabolic reactions

Question 14

when temp decr (4)

Answer 14

1. arterioles vasoconstrict, shunt vessels dilate (less blood to skin capillaries, less heat removed by conduction, convection, radiation)
2. shivering: spasmodic contractions of skeletal muscles, incr rate of resp
3. hair erector muscles contract, hair stands, more air/heat trapped (insulation)
4. incr rate of metabolic reactions