Communication and Homeostasis

Question 1

What conditions do cells need to maintain?

Answer 1

Temperature
pH
Aqueous environment (solute concentrations)
Freedom from toxins and inhibitors

Question 2

What will happen if conditions are compromised?

Answer 2

Cells will be damaged, become inactive and potentially die.

Question 3

Why do cells communicate?

Answer 3

Cells all all specialised for a specific purpose

Need to communicate so they can carry out functions smoothly

Question 4

How do he actions of the cells alter their own external environment?

Answer 4

Some products of metabolic reactions are toxic

They are moved out of the cell into the tissue fluid

Therefore altering the external environment of the cell

Question 5

How does the body maintain its internal environment?

Answer 5

Moves toxins into tissue fluid

These then move into blood

Moved to excretory organs (kidneys and liver)

Excreted

Question 6

List features of a good communication system

Answer 6

Cover the whole body

Enable cells to communicate with each other

Enable specific communication

Rapid communication

Enable both long and short term responses

Question 7

How does cell singanling work?

Answer 7

Cells release a specific chemical

Second cell has a receptor for this chemical which it binds to sending the message

Question 8

What are the 2 major communication systems?

Answer 8

Neuronal System

Hormonal system

Question 9

How does the neuronal system work?

Answer 9

network of neurons that signal to each other via synapses

Can send signals very quickly and responses are rapid

Question 10

How does the emdocrine system work?

Answer 10

Uses the blood to send signals

Endocrine system secretes hormones directly into blood

Response takes longer to come to effect but enables a longer term response

Question 11

What does homeostasis regulate?

Answer 11

Body temp
Blood glucose concentration
Blood salt concentration
Water potential of blood
Blood pressure
CO2 Concentration

Question 12

What are sensory receptors?

Answer 12

Sensory receptors are on the surface of the body

They monitor the external environment and alert the body to change

When stimulated it sends a signal to an effector

Question 13

What is an Effector?

Answer 13

Cells that bring about a response

such as Muscle (sarcomeres) or liver cells (hepatocytes)

Question 14

What is negative feedback?

Answer 14

A change is detected

The body responds in opposition to this change

Return the body to optimum

Question 15

What is positive feedback?

Answer 15

A change is detected

The body reacts to exacerbate this change

This moves the body away from optimum so is usually harmful

Question 16

Why is positive feedback often harmful?

Answer 16

Because it moves the body away from optimum conditions

Enzymes can become less effective and even become denatured

Impacts metabolic reactions causing harm to the body

Question 17

What is an example of where positive feedback is beneficial the body?

Answer 17

Cervix dilation during labour

The body detects the stretch of the cervix

The pituitary gland releases oxytocin which increases uterine contractions causing the crevix to stretch more

This is essential for a safe delivery of the baby

Question 18

What is an endotherm?

Answer 18

An organism that regulates its own internal body temperature

Very strict tolerances

largely independent of external factors

Question 19

What is an ectotherm?

Answer 19

Can’t control own body temp

rely on external sources

use behavioral mechanisms to maintain body temperature in different conditions

Question 20

Give examples of how ectotherms maintain body temp

Answer 20

Too hot:
Move to a sunny area/ lie on a warm surface
expose more of their surface area to the sun

Too cold:
Move out the sun
Move underground
reduce surface area exposed to the sun

Question 21

Give 4 advantages of Ectothermy

Answer 21

Less energy used in respiration

More nutrients gained from food (because less energy is required)

Don’t need to find food as often

Can survive long periods without any food

Question 22

Give a disadvantage of Ectothermy

Answer 22

Less active in cold environments

so they are more at risk from predators when it is cold

Question 23

Give 3 advantages of Endothermy

Answer 23

Can maintain fairly constant temperature despite external conditions

Remain active even when environment is cold

Can inhabit colder parts of the planet

Question 24

Give 4 disadvantages of Endothermy

Answer 24

Use energy in order to maintain body temperature in cold conditions

Require more food

Less energy can be used towards growth

Can overheat in hot conditions

Question 25

Where are the temperature receptors in the brain?

Answer 25

Hypothalamus

Question 26

What is the role of periphery temperature receptors?

Answer 26

To give the hypothalamus an early warning that core body temperature could change