Control and Regulation 3

Question 1

What are the similarities between nervous and endocrine system?

Answer 1

Control important aspects of body function and maintain homeostasis

Question 2

What are the differences between nervous and endocrine system?

Answer 2

Nervous;
Inside and outside
Fast to detect changes Immediate to respond
Network of nerves
Endocrine:
Mostly inside
Slower and more prolonged responses
Number of distinct glands

Question 3

Describe endocrine glands:

Answer 3

Endocrine glands are ductless
Endocrine glands secrete hormones into intercellular spaces which diffuse into the blood and are carried to the target organ.
No direct anatomical links

Question 4

What are the 3 major classes of hormones?

Answer 4

Protein hormones (water soluble)
e.g.: insulin, glucagon,
Steroid hormones (lipid soluble)
e.g.: thyroid, oestrogen
Amine hormones (water soluble)
e.g.: adrenaline, thyroxine

Question 5

Describe protein hormones

Answer 5

Hydrophilic
Bind to receptors on the surface of “target” cells
Alter the behaviour of the cell
Stimulate (or repress) gene expression in the nucleus by turning on (or off) the promoters and enhancers of the genes

Question 6

Describe steroid hormones:

Answer 6

Hydrophobic
Diffuse freely inside “target” cells
Hormone binds to the receptor and the complex binds to hormone response elements - stretches of DNA within the promoters of genes responsive to the hormone
Hormone/receptor complex acts as a transcription factor turning target genes “on” (or “off”).
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Question 7

Describe the differences in feedback regulation between positive and negative:

Answer 7

Negative feedback – reverse deviations from
normal
Positive feedback – amplify deviations from
normal

Question 8

What are the 2 cues that trigger thirst?

Answer 8

Hypovolaemic thirst is stimulated by reduced extracellular volume.
Osmotic thirst is stimulated by high extracellular solute concentration

Question 9

Where does circulating angiotensin II act

Answer 9

circumventricular organs