Homeostasis And Chemical Control In Mammals

Question 1

What is homeostasis?

Answer 1

The maintenance of a constant internal environment despite external change

Question 2

What is negative feedback?

Answer 2

The reversal of a change to a steady state

Question 3

Negative feedback flow diagram

Answer 3

Optimum condition 
Change away from op
Receptor detects change 
Communication system informs effector 
Motor neurone 
Effector reacts to make change 
Negative feedback 
Back to optimum condition

Question 4

The communication pathway

Answer 4

Stimulus 
Receptor
Cell signalling 
Effector 
Response

Question 5

What is positive feedback?

Answer 5

Increases change detected by receptors

Question 6

Flow diagram of positive feedback

Answer 6

Optimum condition
Change away from optimum
Receptor detects change
Communication system
Effector reacts to increase change

Question 7

The endocrine system: endocrine glands

Answer 7

Secrete hormones into the bloodstream

Question 8

The endocrine system: exocrine glands

Answer 8

Secrete enzymes that are secreted outside the body

Question 9

What is a hormone

Answer 9

Chemical messengers that act on particular target cells

Question 10

What are the 2 types of hormones

Answer 10

Protein and peptide hormones

Steroid hormones

Question 11

Protein and peptide hormones

Answer 11

Adrenaline insulin and glucagon

Not soluble in the lipid bilayer- can’t diffuse through so don’t enter the cell

Question 12

Steroid hormones

Answer 12

Sex hormones

Can diffuse through the membrane and have direct effect on DNA

Question 13

What does the adrenal gland do?

Answer 13

Secretes Adrenalin

Question 14

What does adrenaline do?

Answer 14

Increase heart rate, stroke volume, vasoconstriction to non essential organs, relaxed smooth muscle in bronchioles and inhibit action of gut

Question 15

Negative feedback loop for insulin control: Beta

Answer 15

Blood glucose levels up
Beta cells as receptors and effectors 
Insulin released 
Body cells take up more glucose 
Blood glucose level declines

Question 16

Negative feedback loop for insulin control: alpha

Answer 16

Blood glucose level drops
Alpha cells of pancreas release glucagon into blood
Liver breaks down glucagon and releases glucose
Blood glucose level rises

Question 17

What does the hypothalamus do?

Answer 17

Monitors blood levels and hormones- responds by controlling the activity of the pituitary which secretes hormones

Question 18

Pituitary gland: anterior lobe

Answer 18

Produces 6 hormones including FSH

Question 19

Pituitary gland: posterior lobe

Answer 19

Stores and releases hormones from hypothalamus including ADH

Question 20

Type 1 neurosecretory cells in the hypothalamus

Answer 20

Produce substances that stimulate the release of hormones from the anterior pituitary (which can be releasing factors or release inhibiting factors)

Question 21

Type 2 neurosecretory cells in the hypothalamus

Answer 21

Produce secretions that are stored in the posterior pituitary gland which are released later as hormones

Question 22

Hormones and the second messenger: protein and peptide hormones

Answer 22

Hormone binds to the receptor which is transmembrane as hormone cannot enter the cell. Enzyme/substrate complex= second messenger cAMP (Cyclic AMP.) Response. The second messenger is needed as the hormone can’t enter the cell

Question 23

Hormones and the second messenger: steroid hormones

Answer 23

Receptor protein- diffusion into cell- hormone/receptor complex- can act as a transcription factor- protein synthesis

No need for second messenger

Question 24

ATCH

Answer 24

Stimulates adrenal gland to secrete hormones

Question 25

FSH

Answer 25

Stimulates ovaries to secrete oestrogen and development of ova

Question 26

LH

Answer 26

Stimulates Ovulation

Question 27

Prolactin

Answer 27

Stimulates milk production in mammary glands

Question 28

ADH

Answer 28

Decrease urine volume to conserve water

Question 29

Oxytocin

Answer 29

Stimulates contraction of uterus during childbirth