Homeostasis

Question 1

What is homeostasis?

Answer 1

The maintenance of a constant internal environment.

It gives us a survival advantage and is needed for proper functioning.

Question 2

What are the main components of a homeostatic system?

Answer 2

1. Input
   2.receptor
   3.coordinator
   4.effector
   5.output
   Feedback loop

Question 3

Input

Answer 3

This is a change to the system which requires a cell to react

Question 4

Receptor

Answer 4

The change is detected in a living system.

Question 5

Coordinator

Answer 5

Operational information is stored here and used to coordinate effectors

Question 6

Effector

Answer 6

Brings about changes to the system in order to return it to the optimum point

Question 7

Output

Answer 7

System returned to optimum point

Question 8

Feedback loop

Answer 8

Positive or negative feedback

Question 9

Positive feedback

Answer 9

When a deviation from the optimum point causes change that results in an even greater deviation from the normal.

Question 10

Example of positive feedback

Answer 10

Influx of sodium ions in the neurone

This is because more is added in to the neurone

Question 11

What is a con of POSITIVE FEEDBACK?

Answer 11

Usually harmful as it leads to instability

NOT INVOLVED IN HOMEOSTASIS

Question 12

What is negative feedback?

Answer 12

Negative feedback occurs when the stimulus causes the corrective measures to be turned off so it returns the system to its original (optimum) level and prevents overshoot.

Question 13

What is an ectotherm?

Answer 13

animals that obtain heat from sources outside the body, such as the environment.

Question 14

What is an endotherm?

Answer 14

An animal that derives most of their hear from metabolic activities that take place inside their bodies.

Question 15

Name 3 ways ectotherms regulate body temperature

Answer 15

Exposing themselves to the sun
Taking shelter
Gaining warmth from the ground

Question 16

Describe how ectotherms exposing themselves to the sun regulated body temperature

Answer 16

Lizards orientate themselves so the maximum surface area of their body is exposed to the warming rays of the sun

Question 17

Describe how taking shelter helps ectotherms regulate body temperature

Answer 17

Lizards will shelter in the shade to prevent over heating when the suns radiation is at its peaks.
They retreat to burrows in order to reduce heat loss when the external temperature is low.

Question 18

Describe how gaining warmth from the ground helps ectotherms in regulating body temperature

Answer 18

Lizards will press their bodies against areas of hot ground to warm themselves up.
When they get to the right temperature they raise themselves up with their legs.

Question 19

Name 5 ways endotherms conserve and gain heat in response to a cold environment

Answer 19

Vasoconstriction 
Shivering
Raising of hair
Increased metabolic rate
Decrease in sweating

Question 20

Describe how vasoconstriction hells endotherms conserve and gain heat in response to a cold environment

Answer 20

The diameter of the arterioles near the skin become smaller.
This reduces the volume of blood reaching the skin surface through capillaries.
Most of the blood entering the skin passes beneath an insulating fat layer and so very little heat is lost.

Question 21

Describe how shivering helps endotherms conserve and gain heat in response to a cold environment

Answer 21

The muscles of the body undergo involuntary rhythmic contractions that produce metabolic heat.

Question 22

Describe how the raising of hair helps endotherms conserve and gain heat in response to a cold environment

Answer 22

The hair erector muscles in the skin contracts, raising the hairs.
This enables a think layer of still air which acts as a good insulator.

Question 23

Describe how increased metabolic rate helps endotherms conserve and gain heat in response to a cold environment

Answer 23

In colder conditions more of the hormones to increase metabolic rate are produced, as a result metabolic activity, including respiration is increased and so more heat generated.

Question 24

Homeostasis and PH

Answer 24

If PH is too high or too low enzymes become denatured, this causes hydrogen bonds to break and the active site changes shape.
This means they cant do their job as biological catalyst and metabolic reactions are slowed down.
PH 7 is optimum for enzyme activity

Question 25

Temperature and enzymes

Answer 25

If the body temperature is too high enzymes become denatured.
Excessive vibration breaks the hydrogen bonds and changes the shape of the active site so cant as catalysts.

If the temperature is too low, enzyme activity if reduced therefore metabolic reactions are slowed down

OPTIMUM TEMPERATURE IS 37 DEGREES

Question 26

3 types of hear transfer to the environment

Answer 26

Conduction
Convection
Radiation