Unit 3 - Homeostasis

Question 1

Postive VS Negative Feedback

Answer 1

Positive feedback response adds to the stimulus increasing the response. Examples include childbirth and blood clotting
Whereas, Negative feedback response eliminates or reduces the stimulus . Examples include increase in body temperature etc

Question 2

Define Homeostasis

Answer 2

Homeostasis refers to the maintenance of relatively constant internal environment independent of the changing external environment.

Question 3

Describe a feedback system

Answer 3

Stimulus - Change in environment
Receptor - Detects change in environment and sends this message to modulator
Modulator - Receive message and initiates response
Effector - Carries out response
Response - what is caused by the effector
Feedback - Environment back to normal

Question 4

What are the organs involved in the regulation of blood glucose

Answer 4

Liver - stores glucose
Pancreas - A cells and B cells secrete hormones
Adrenal Glands - Secretion of Cortisol

Question 5

Increase in blood glucose

Answer 5

S - Increase in blood glucose
R - Carotid Chemoreceptors detect increase in BG
M - Hypothalamus receives and initiates response through the effectors
E - Pancrease secretes Insulin through Beta Cells
- Liver converts glucose into glycogen for storage through glycogenesis
R - Insulin promotes glycogenesis in the liver
- liver keeps glucose out of the blood for storage
F - Decrease in blood glucose

Question 6

decrease in blood glucose

Answer 6

S - Decrease in BG
R - Carotid chemoreceptors in heart detect increase in BG
M - Hypothalamus receives message and activates the liver, pancreas, and adrenal glands
E
- Pancreas secretes Glucagon from Alpha Cells
- Liver converts glycogen into glucose through glycogenolysis
- adrenal glands secrete cortisol
R
- Glucagon initiates glycogenolysis
- Liver releases glucose into the blood
- Cortisol regulates carbohydrate metabolism by ensuring enough energy is provided
F - Increase in BG

Question 7

role of the liver

Answer 7

1. glucose is removed for energy
2. glucose is removed by the liver/muscles and converted to glycogen for storage
   3.glucose continue to circulate the body

Question 8

types of cells in IOL pancreas

Answer 8

alpha:
- secrets glucagon = increase blood glucose
- converts glycogen into glucose (glycogenolysis)
beta:
- secretes insulin = decrease blood glucose
- converts glucose to glycogen = glycogenesis
- glucose into protein = protein synthesis
- glucose into lipids = lipogenesis
*hormones travel via HPV

Question 9

insulin

Answer 9

• hormone that decreases blood glucose levels through:
  1. glycogenesis
  2. lipogenesis
  3. protein synthesis
  4. translocation

Question 10

glucagon

Answer 10

• hormone that increase blood glucose levels through:
  1. glycogenolysis
  2. gluconeogenesis
  3. lipolysis

Question 11

role of adrenal glands

Answer 11

• above kidney, raise blood glucose levels
  Adrenal Cortex secretes cortisol
  1. regulates carbohydrate metabolism
  2. stimulates the rate of removal of amino acids from cells and transported to the liver
  2. glycogenolysis
  3. gluconeogenesis
  Adrenal medulla secretes adrenaline & noradrenaline
  1. glycogenolysis
  2. stimulate production of lactic acid which is then converted to glucose in the liver

Question 12

Organs involved in thermoregulation

Answer 12

Skin - Vaso, sweating, radiation, evaporation
Muscles - movement
Adrenal medulla - secretion of hormones

Question 13

Increase in body temperature

Answer 13

S - Increase in BT
R - Peripheral thermoreceptors in skin
M - Hypothalamus
E
- Skin sweats
- Vasodilation of skin arterioles
- Decrease in metabolic rate
- Behavioural Response
R
- Vasodilation causes increase in blood flow through the skin due to the higher SA - causing heat loss through convection
- Sweating causes evaporation
- decreased metabolic rate causes a decrease in heat production
F - Decrease in BT

Question 14

decrease in body temperature

Answer 14

S - Decrease in BT
R - Peripheral thermoreceptors in skin
M - Hypothalamus
E
- Skeletal muslces shiver
- vasoconstriction
- adrenal medulla secretes adrenaline & noradrenaline
- pituitary releases TSH - releases thyroxine
- Behavioural Response
R
- Shivering produces heat by movement
- vasoconstriction causes a reduction in heat loss
- adrenaline and noradrenaline increase metabolic rate causing greater heat production
- thyroxine also increases metabolic rate
F - Increase in BT

Question 15

Define heat stroke and hypothermia

Answer 15

Heatstroke - the failure of a person’s temperature regulating mechanisms when exposed to excessive heat
Hypothermia - temperature drops below the level required to maintain normal body functions

Question 16

Organs involved in bodily fluids

Answer 16

Kidney - Main site of reabsorption and excretion
Adrenal gland - secretes key hormones
Posterior lobe of pituitary - secretes hormones

Question 17

ADH

Answer 17

• made in hypo, stored in posterior lobe
• controls permeability of CD & DCT
• increase absorption of water back into the blood = raise water plasma levels = decrease urine
• water conc dec = ADH released
• water conc inc = ADH inhibited

Question 18

Increase in water concentration

Answer 18

S - Increase in water concentration
R - Osmoreceptors in thirst centre of hypothalamus detect decrease in osmotic concentration and increase in plasma volume
M - Thirst centre
E
- Kidney begins with excretion
- Adrenal gland secretes aldosterone to maintain sodium levels
R
- Kidney excretes larger volumes of water at a faster rate
- aldosterone maintains sodium levels of the body
F - Decrease in water concentration

Question 19

Decrease in water concentration

Answer 19

S - decrease in water concentration
R - osmoreceptors detect decrease in plasma volume and increase in osmotic concentration
M - Thirst centre
E
- Posterior lobe of pituitary gland secretes ADH
- thirst centre initiates thirst response
R
- ADH increase permeability of the DCT and collecting ducts of the nephron, meaning more water is reabsorbed into the blood stream
- Thirst response causes the person to drink water
F - increase in water concentration

Question 20

Too much or TOO little water

Answer 20

Too little = Dehydration
Dehydration causes;
- severe thirst
- low BP
- dizziness
- headache

Too Much = Water intoxication
Water intoxication causes;
- lightheadedness
- vomiting
- collapse
- headache
- excessive urination

Question 21

Organs involved in gas concentrations

Answer 21

Diaphragm, intercostal muscles, lungs

Question 22

Increase in CO2 concentration

Answer 22

S - Increase in CO2 concentration
R - Chemoreceptors in the carotid bodies and the respiratoryc centre
M - Respiratory centre in the medulla oblongata
E - Diaghragm and intermuscle have an increased rate and depth of breathing
R - More CO2 is excreted and O2 is intaken
F - Decrease in CO2 Concentration

Question 23

Decrease in CO2

Answer 23

S - Decrease in Co2
R - Chemoreceptors in the carotid body and respiratory centre
M - respiratory centre in the medulla oblongata
E - Intercostal muscles and diaphragm
R - decreased rate and depth of breathing
F - Increase in Co2

Question 24

vasodilations vs vasoconsctriction

Answer 24

Vasodilation - increase in heat loss - widening of blood vessels

Vasoconstriction - reduction in heat loss - shortening of blood vessels

Question 25

what are disruptions to homeostasis

Answer 25

Disruptions to homeostasis are;

Hormonal - Insulin & Thyroxine
Behavioural - Drugs, Exercise, Eating Habits
Disease - Emphysema, Fever, Hypertension