5.1.1 communication and homestasis

What is homeostasis?

maintaining a constant internal environment despite internal and external changes.

What are some examples of internal factors that must remain constant?

Glucose - present for respiration ensures water potential is constant.

Internal temperature - enymes catalyse at optimum temps.

Water potential - prevents cell shrnking or bursting.

pH

Why are communication systems important?

1. Need to respond to behavioral or physiological changes

2. Needed for homeostasis, exceret waste/toxic susbtaces.

What are 2 systems the communication system works in?

1. Nervous system

2. Endocrine system

What is the response pathway?

Stimulus — Receptor — Cell singalling — Effector — Response

What type of feedback takes part in homeostasis?

Negative feedback

What type of feedback doesnt take part in homeostasis?

Positive feedback

What is the definition of negative feedback?

When a change occurs however the body reverses this change.

Example of negative feedback which links to thermoregulation.

Temp drops — detected by thermorecptors in hypothalumus — response generated to bring temp back up.

If an exam quesion mentions ‘temperature’ what must you include in your answer?

Relate back to enzyme activity.

Example of a postive feedback

Temp drops — exergonic reactions slowed down due to less enzyme acticity, less KE — less heat released so temp falls more.

Use of positive feedback?

Labour

Process of labour?

1. Cervix dilates

2. Oxytocin released due to muscle contraction

3. Oxytocin increases contractions

4. Cervix streches more

Examples of core body parts?

Lungs, Heart, Liver, ALL organs

Example of peripheral body parts?

Fingers, Toes, Hands, Legs

What are behavioral responses of ectotherms?

1. Move away/towards the sun

2. Lie on warm surface

3. Increase/decrease their SA

Advanatges of ectotherms?

• Need less food- as they dont need glucose to respire as they dont need to keep themselves warm.

• Moe nutrinets used for growth.

Disadvantages of ecotherms?

• Less active at cooler temps

In humans what detects temperature changes in your blood?

Thermoreceptors

What are some behavioral responses to edotherms in a hot environment?

• Hide away from the sun

• Reamin inactive

• Wet skin so evaporation transfers heat

What are some behavioral responses to edotherms in a cold environment?

• Lie in the sun

• Move about

• Remain dry

What are some physlogical responses to edotherms in a hot environment?

• Sweat released

• Hairs are flat

• Vasodilation

• Panting - increases evpaoration and heat transfer.

What are some physlogical responses to edotherms in a cold environment?

• No sweat muscle

• Hairs erect

• Vasoconstricion

• Less panting

Advantages of endotherms?

• Maintain constant body temp

• Remain active even if external body temps fall.

Disadvantages of endotherms?

• Lots of energy needed to regulate body temp

• Need more food and less used for growth, more used for respiration

What causes vasodilation and vasoconstriction?

Thermoregulators

What happens during vasodilation?

• Aterioles widen

• More blood flows through to capillary network

• Precapillary sphicter are open

• More heat energy is lost from your skin

What happens during vasoconstriction?

• Aterioles close

• Precapillary sphicter close

• Less blood flows through to capillary network

• Less heat lost