Communication and Homeostasis 5.1

Question 1

What is an effector?

Answer 1

Organ tissue or cell that produces a responce to a stimulus

Question 2

What is homeostasis?

Answer 2

The act of maintaining a constant internal environment around an optimum despite external change

Question 3

What are hormones?

Answer 3

Cell signaling molecules that travel to target cells and bind to specific receptors to initiate a response

Question 4

What is negative feedback?

Answer 4

A process that counteracts change to maintain an equilibrium around a normal level

Question 5

What is a positive feedback?

Answer 5

A process which causes an increase in change away from the normal level

Question 6

What are characteristics of hormonal communication?

Answer 6

• uses blood to carry messages
• long lasting
• uses chemicals
• slow responce
  target cells

Question 7

What are the characteristics of nuronal communication?

Answer 7

• uses neurones to carry messages
• short lasting
• uses electrical impulses
• quick response
• synapses

Question 8

Why do we maintain a constant internal environment?

Answer 8

• to give enzymes optimum conditions
  (temp, PH, aqueous environment and no inhibitors)

Question 9

Why do we need a good communication system?

Answer 9

• to cover the whole body
• enable specific communication
• enable rapid communication
• enable cells to communicate with eachother
• enable short and long term responses

Question 10

What are things that have to be maintained at a constant level?

Answer 10

• body temp
• blood glucose conc.
• water potential in blood
• blood salt conc.
• CO2 conc.
• blood PH

Question 11

What are examples of positive feedback loops?

Answer 11

• cervix dialating during birth
• blood clotting

Question 12

How does homeostasis work?

Answer 12

• receptors detect a change
• stimulates effectors to cause a response
• response counteracts the change
  (negative feedback)

Question 13

What is an ectotherm?

Answer 13

A type of organism which depends on its ebvironment to maintain body temperature

Question 14

What are examples of ectotherms?

Answer 14

Fish, reptiles, amphibians, insects

Question 15

What are behavioural ways to regulate body temperature for ectotherms?

Answer 15

• seek the sun
• seek the shade
• seek cooler water
• brumination
• estivation
• spread limbs out
• open mouth and pant
• turn body sideways towards sun

Question 16

What are physiological ways to regulate body temperature for ectotherms?

Answer 16

• change colour (pale grey or black)
• increase or decrease heart rate

Question 17

What is an endotherm?

Answer 17

A type of organism that uses metabolic processes to warm up and maintain a constant core temperature without using external sources

Question 18

How is temperature change detected on the skin?

Answer 18

Through temperature receptors on the skin

Question 19

How is temperature change detected internally?

Answer 19

Through temperature receptors in the thermoregulatory centre in the hypothalamous

Question 20

What are behavioural ways to regulate body temperature for endotherms?

Answer 20

• drink water
• move into shade
• find cool water
• remain inactive
• move into sunlight
• move around more
• increase SA exposed to sun

Question 21

What are physiological ways to regulate body temperature for endotherms?

Answer 21

• sweating
• vasodilation, vasoconstriction
• decrease or increase metabolic rate
• panting
• hairs lie flat
• no spontaneous contraction
• shivering
• piloerection
• release of adrenaline and thyroxine
• less sweating