5.1-NOmeostasis

Question 1

What’s an example of an an animal responding to gradual change ?

Answer 1

Arctic fox- thick white coat in winter, thinner grey brown coat in summer- greater insulation and camouflage, enabling survival.

Question 2

What will a good communication system do ?

Answer 2

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

Question 3

What are the 2 major systems of communication?

Answer 3

Neuronal system

Hormonal system

Question 4

What is the neuronal system?

Answer 4

An interconnected network of neuronal that signal to eachother across synapse junctions. The neurons can conduct a signal v quickly + enable rapid responses to stimuli that may be changing v quickly.

Question 5

What is the hormonal system?

Answer 5

System that uses the blood to transport its signals. Cells in an endocrine organ release the signal-a hormone-into the blood. The hormone is transported throughout the body but is only recognised by specific target cells. The hormonal system enables longer term responses to be coordinated.

Question 6

What is an effector ?

Answer 6

A cell, tissue, or organ that brings about a response.

Question 7

What is homeostasis?

Answer 7

Maintaining a constant internal environment despite changes in external and internal factors.

Question 8

Whah is negative feedback?

Answer 8

The mechanism that reverses a change, bringing the system back to the optimum.

Question 9

What is positive feedback?

Answer 9

The mechanism that increases a change, taking the system back away from the optimum.

Question 10

What is sensory receptor?

Answer 10

Cells/ sensory nerve endings that respond to a stimulus in the internal or external environment of an organism and can create action potentials.

Question 11

What conditions do living things need to maintain?

Answer 11

Temperature
pH
Aqueous environment that keeps substrates and products in solution
Freedom from toxins and excess inhibitors

Question 12

What are some aspects maintained by homeostasis ?

Answer 12

Body temperature 
Blood glucose concentration 
Blood salt concentration 
Water potential of blood
Blood pressure 
CO2 concentration

Question 13

What is an example of positive feedback?

Answer 13

At the end of pregnancy to bring about dilation of the cervix: as cervix stretches posterior pituitary gland secretes oxytocin, which increases uterine contractions, which stretches the cervix more, which causes more secretion of oxytocin.

Question 14

What is an ectotherm?

Answer 14

An organism that relies on external sources of hear to maintain body temperature.

Question 15

What is an endotherm?

Answer 15

An organism that uses heat from metabolic reactions to maintain body temperature.

Question 16

Do ectotherms or endotherms control their body temperature within very strict limits and why?

Answer 16

ENDOtherms control their body temperature within very strict limits.
Ectotherms aren’t able to because they rely on external sources of heat so their body temp fluctuates with external temp.

Question 17

If ectotherms are cold what do they do?

Answer 17

Move to a sunny area
Lie on a warm surface
Expose a larger surface to the sun

Question 18

If ectotherms are warm what do they do?

Answer 18

Move out of the sun
Move underground
Reduce body surface exposed to the sun

Question 19

Is a lot of ectotherms’ food used for respiration?

Answer 19

Nah, because they rely on external sources to keep warm

Question 20

What are the advantages of being an ectotherm?

Answer 20

Less food used in respiration
More energy gained from food can be converted to growth
Need to find less food
Can survive for longer periods without food

Question 21

What are the disadvantages of ectothermy?

Answer 21

Less active in cooler temperatures- at risk from predators when cold, unable to escape, can’t take advantage of food available when cold.

Question 22

What does the skin do if the body is too hot ?

Answer 22

Sweat glands secrete fluid onto skin surface
Hairs and feathers lie flat to reduce insulation+allow greater heat loss
Vasodilation of arterioles and precapillary sphincters directs blood to skin surface so more heat can be radiated out.

Question 23

What does the gaseous exchange system do if the body’s too hot?

Answer 23

Panting, increasing evaporation of water from surface of lungs and airways- latent heat of vaporisation

Question 24

What does the skin do when endotherms are too cold?

Answer 24

Less sweat secreted
Hairs and feathers stand erect to trap sit
Vasoconstriction of arterioles and precapillary sphincters leading to skin surface - blood diverted away from skin.

Question 25

What does the gas exchange system do in endotherms when cold?

Answer 25

Less panting

Question 26

What does the liver do when endotherms are too hot?

Answer 26

Less respiration-less heat released

Question 27

What does the liver do when endotherms are too cold?

Answer 27

Increased respiration in hepatocytes- more energy from food converted to heat

Question 28

What do the skeletal muscles do when endotherms are too hot?

Answer 28

Fewer contractions- less heat releases

Question 29

What do skeletal muscles do when endotherms are too cold?

Answer 29

Spontaneous muscle contractions- shivering- to release heat

Question 30

What do blood vessels so when endotherms are too hot?

Answer 30

Dilation to direct blood to extremities so more heat can be lost

Question 31

What do blood vessels do when endotherms are too cold ?

Answer 31

Construction to limit blood flow to extremities

Question 32

What are the advantages of endothermy?

Answer 32

Endotherms can:
Maintain a constant body temp despite outside conditions
Remain active even when external temps are low so can take advantage of prey+ escape predators
Inhabit colder parts of planet

Question 33

What are the disadvantages of endothermy?

Answer 33

Use a significant part of energy to maintain body temp in cold
Need more food
Use for growth a lower proportion of energy gained from food
May overheat in hot weather

Question 34

what are some examples of ectotherms?

Answer 34

snake
locust
lizard
horned lizard

Question 35

what does the locust do to its breathing when it’s hot and why?

Answer 35

increases rate and depth of breathing-more water evaporates from tracheal system, cooling body.

Question 36

what monitors core body temperature?

Answer 36

temperature receptors in thermoregulatory centre of hypothalamus

Question 37

what monitors temperature at the extremities?

Answer 37

peripheral temprature receptors in skin

Question 38

why would something be described as endothermic?

Answer 38

it produces its own heat from RESPIRATION so doesn’t rely on the surroundings for heat. gotta say respiration.