Homeostasis and homeostatic mechanisms of the major functional systems. Control system of the body. Characteristics of control systems.

Question 1

homeostasis definition

Answer 1

when the body maintains a stable internal environment during changes in external environment

to maintain dynamic equilibrium for cell function

Question 2

homeostasis - nervous system function

Answer 2

coordinates + controls brain + body activity

Question 3

homeostasis - nervous system mechanism

Answer 3

1 - receptors detect stimuli
2 - sensory neurones send electrical signal from receptor to CNS
3 - integration centre = brainstem/ spinal cord
4 - motor neurones send electrical signals from CNS to effector
5 - effector = muscle/ gland

= responds rapidly to changes in external environment

Question 4

homeostasis - nervous system example

Answer 4

when thermoreceptors detect change in temp
sent to hypothalamus
heat loss/ heat gain mechanism

Question 5

endocrine system - function

Answer 5

long term regulation of
- growth
- metabolism
- reproduction
via hormones

Question 6

endocrine system - mechanism

Answer 6

endocrine gland release hormones which regulate functions

helped by negative feedback loops where increase in hormone triggers response to decrease it back down

Question 7

endocrine system -

example

Answer 7

regulation of blood sugar conc of insulin/ glucagon

Question 8

circulatory system function

Answer 8

deliver nutrients + remove waste

Question 9

circulatory system mechanism

Answer 9

baroreceptor reflex
chemoreceptor reflex
bainbridge reflex

Question 10

circulatory system example

Answer 10

regulation of BP by RAAS

• kidneys detect low BP and secrete renin into bloodstream
• renin converts angiotensinogen into angiotenin I
• ACE converts angiotensin I into angiotensin II
• angiotenin II is a potent vasoconstrictor = increase BP

Question 11

respiratory system function

Answer 11

responsible for gas exchange of O2 + CO2 between cells + environemt

Question 12

respiratory system mechanism

Answer 12

chemoreceptor reflex

Question 13

respiratory system - example

Answer 13

during excercise = more breathing to get more o2/ remove co2

Question 14

renal system function

Answer 14

• filtration of blood
• controlling volume/ concentrated urine
• regulating water/ electrolyte balance

Question 15

renal system mechanism

Answer 15

kidneys key processes
- secretion
- filtration
- absorption

Question 16

renal system - example

Answer 16

maintain pH by buffering blood containing hco3- and h+

Question 17

digestive system function

Answer 17

breakdown food into bolus containing nutrients to be absorbed into bloodstream

Question 18

digestive system mechanism

Answer 18

• neural
• hormonal

Question 19

digestive system example

Answer 19

salivary glands break down food

Question 20

control system - 1

Answer 20

a change in stimulus triggers a response to counteract this stimulus to bring it down to normal level

e.g. thermoregulation
- heating production mechanisms
- heat loss mechanisms

Question 21

control system - 2

Answer 21

a change in stimulus triggers a response to amplify this stimulus to increase it

e.g. blood-clotting mechanism, more growth factors released by phagocytes of wound to increase repair

Question 22

control system - 3

Answer 22

set points

• there is an ideal value for the physiological parameter
  body temp = 36.7
  pH = 7.36-7.44
  glucose = 70mg/dL-100mg/dL

Question 23

control system - 4

Answer 23

sensors

• peripheral thermoreceptors - in skin
• central thermoreceptors - in hypothalamus

Question 24

control system - 5

Answer 24

detection

anterior hypothalamus
- activating heat loss mechanism

posterior hypothalamus
- activating heat gain mechanism

Question 25

list examples of homeostasis regulation

Answer 25

blood glucose

blood pressure

blood pH

calcium balance

fluid balance

Question 26

blood glucose mechanism

Answer 26

high blood glucose

• after eating, insulin into pancreas
• insulin helps uptake glucose to store into glycogen in liver
• this lowers glucose

low blood glucose

• during fasting
• glucagon into pancreas
• glucagon breaks down glycogen into glucose dispersing into liver

Question 27

blood pressure mechanism

Answer 27

baroreceptor reflex

• located on carotid body/ arcus aorta
• baroreceptors detect changes in stretch/ pressure in large blood vessel walls

high bp (hypertension) the baroreceptors get stretched more, more signals sent to medulla oblongata

low bp (hypotension) the baroreceptors get stretched less, signals more signals sent to medulla oblongata

Question 28

blood pH mechanism

Answer 28

acidosis

• kidneys excrete H+ / absorb HCO3- to reduce acid levels

alkolosis

• kidneys keep H+ / remove HCO3- to reduce alkaline levels

Question 29

calcium levels mechanism

Answer 29

high calcium
- thyroid hormone acts
- decreasing absorption in intestines
- increases excretion in kidneys

low calcium
- parathyroid gland acts
- increasing absorption in intestines
- reducing excretion in kidney

Question 30

fluid balance regulation

Answer 30

overhydration
- ADH inibited by posterior pituitary gland causing kidneys to release water producing dilute. urine
- RAAS system suppressed to lose sodium + water

dehydration
- ADH released by posterior pituitary gland causing kidneys to reabsorb water producing conc. urine
- RAAS system activation to retain sodium + water