Communication and Homeostasis

Question 1

The need for communication systems in multicellular organisms

Answer 1

• to respond to changes in the internal/external environment

- to coordinate organ function

Question 2

What is cell signalling?

Answer 2

• communication between cells(hormonal or neuronal)
• long distance endocrine signalling
• paracrine signalling occurs between adjacent cells w extracellular fluid

Question 3

What is homeostasis?

Answer 3

-Maintaining stable internal environment within a narrow range, even though external environment is changing

Question 4

What is a receptor?

Answer 4

• cells located in sense organs

- detect specific stimulus

Question 5

What is an effector?

Answer 5

• usually muscles or glands

- enable physical response to stimulus

Question 6

What is negative feedback?

Answer 6

-self regulatory mechanisms return internal environment back to optimum

Question 7

What is positive feedback?

Answer 7

-external change triggers further changes away from optimum

Question 8

What are ectotherms?

Answer 8

• use surrounding environment to warm their bodies
• behavioural adaptations
• invertebrates

Question 9

What are endotherms?

Answer 9

• rely on metabolic reactions to warm up
• physiological and behavioural adaptations
• mammals and birds

Question 10

Thermoregulation in ectotherms

Answer 10

Behavioural Response:
-bask in the Sun(increase surface area)
-pressing their bodies against warm/cold surface(conduction)
-seek shade/shelter(cool down)
Physiological Response:
-darker colours to absorb more radiation
-altering of heart rate to increase/decrease metabolic reactions

Question 11

Thermoregulation in endotherms

Answer 11

• vasoconstriction, arterioles near surface of skin constrict, causing shunt vessels to dilate, less blood flows to surface of skin
• decreased sweating
• raising of body hairs, erector pili muscles contract, raising hair, creating insulating layer of air
• shivering,