5.1 communication and homeostasis

Question 1

The first page is just an introduction so review it

Question 2

What are the two major systems of communication that work by cell signaling?

Answer 2

neuronal system - neurons
hormonal system - blood system

Question 3

What are the aspects maintained by homeostasis?

Answer 3

body temperature
blood glucose concentration
blood salt concentration
water potential of the blood
blood pressure
carbon dioxide concentration

Question 4

What is the standard pathway for homeostasis?

Answer 4

stimulus > receptor > communication pathway > effector > response

Question 5

What are the names for the receptors that detect the stimulus?

Answer 5

sensory receptors

Question 6

What is the input?

Answer 6

The message from the receptor to the coordination centre

Question 7

What is the output?

Answer 7

The messages sent to the effector.

Question 8

What are some examples of effector cells?

Answer 8

liver or muscle cells

Question 9

What is the negative feedback response to a raise in body temperature?

Answer 9

thermo-regulatory centre in hypothalamus detects change
nervous and hormonal system carry signals to skin, liver and muscles
less heat generated and more heat lost
back to optimum

Question 10

What is the negative feedback response to a raise in body temperature?

Answer 10

thermo-regulatory centre in hypothalamus detects change
nervous and hormonal system carry signals to the skin, liver and muscles
more heat generated and less heat lost
back to optimum

Question 11

What is a positive feedback system?

Answer 11

The response is to increaser the initial change, destabilizing the system and can sometimes be harmful.

Question 12

What is the positive feedback system when the body’s core temperature is too low?

Answer 12

the exergonic reactions that heat up the body slow even more and allow the body to cool further

Question 13

What is the positive feedback response during pregnancy?

Answer 13

cervix expands > posterior pituitary gland releases oxytocin > oxytocin increases uterine contractions and cervix expands further > more oxytocin > birth stops oxytocin

Question 14

Are humans endotherms or ectotherms?

Answer 14

Endotherms

Question 15

What is the difference between ectotherms and endotherms?

Answer 15

Endotherms control their internal body temperature
Ectotherms rely on external factors to maintain body temperature

Question 16

What will ectotherms do if it is too hot?

Answer 16

move out of the sun
move underground
reduce body surface exposed to the sun

Question 17

What will endotherms do if it is too cold?

Answer 17

move into a sunny area
lie on a warm surface
expose larger body area to the sun

Question 18

Examples of how ectotherms maintain body temperature?

Answer 18

snakes - bask in the sun
locust - face the sun in the morning with whole body, only head at midday, move away from soil that radiates heat
lizards - use burrows and cervices
horned lizard - can expand ribcage to increase surface area

Question 19

What are the advantages of ectothermy?

Answer 19

less food is used in respiration
more of the energy and nutrients can be used for growth
they need to find less food
can survive with no food for long times

Question 20

What are the disadvantages of ectothermy?

Answer 20

At risk from predators when it is cooler as they try and conserve heat and less food is available

Question 21

What is the skin’s response when it is too hot?

Answer 21

sweat glands secrete fluid to be evaporated
hairs and feathers lie flat to reduce insulation
vasodilation allows capillaries closer to the skin to radiate heat out

Question 22

What is the skin’s response when it is too cold?

Answer 22

less sweat is secreted
hairs and feathers stand erect to maintain heat
vasoconstriction means capillaries are not near skin

Question 23

What does the gaseous exchange system do when it is too hot?

Answer 23

Some animals pant, increasing evaporation in the lungs

Question 24

What does the gaseous exchange system do when it is too cold?

Answer 24

Reduction in panting

Question 25

What does the liver do when it is too hot vs too cold?

Answer 25

too hot - lowered respiration levels in cells
too cold - increased respiration levels due to exergonic reactions

Question 26

What do the skeletal muscles do when it is too hot vs too cold?

Answer 26

too hot - fewer contractions
too cold - spontaneous muscle contractions (shivering)

Question 27

What are the advantages to being an ectotherm?

Answer 27

maintain a constant body temperature
remain active even when there are low temperatures which stops predators and can take advantage of food
inhabit colder parts of the planet

Question 28

What are the disadvantages of being an endotherm?

Answer 28

uses a lot of energy to maintain body temperature
need more food
less energy is used for growth
may overheat in hot weather

Question 29

Where are temperature receptors found?

Answer 29

In the hypothalamus

Question 30

What monitors the external temperature in ectotherms?

Answer 30

peripheral temperature receptors in the skin