Lecture 2

Question 1

Endocrine System

Answer 1

composed of glands that secrete hormones into circulation. They seek the target tissue with particular receptor to induce change.

Question 2

What it involves

Answer 2

1. The regulated secretion of hormones, into the extracellular fluid
2. Diffusion of the hormone to the vasculature and its circulation throughout the body
3. Diffusion of the hormone out of the vascular compartment into extracellular space and binding to a specific receptor within cells of a target organ

Question 3

Autocrine

Answer 3

secretory cell is the target cell. Less hormone needed

Question 4

Paracrine

Answer 4

Secretory cells is adjacent to target cell. Less secreted.

Question 5

Endocrine

Answer 5

Hormone has to travel a long distance to target cell. Gets diluted therefore lots secreted

Question 6

Hormone impact

Answer 6

1. Controlling rate of enzymatic reaction
2. Controlling ion and molecular transport across the membrane
3. Controlling gene expression and protein synthesis

Question 7

termination of hormone action

Answer 7

limiting the secretion of hormone (through feedback loops)

Remove or inactive the hormone in the circulation (degraded by liver and kidney enzymes)

terminating the activity of the hormone in the cell (digesting hormones in lysomes)

Question 8

Physiological response driven negative feedback

Answer 8

Gland, hormone, target organs, physiological effect, circulation component

Question 9

Endocrine axis-driven negative feedback

Answer 9

Hypolothalamic neuroendocrine neurone, releasing hormones, pituitary, trophic hormone, peripheral endocrine gland, hormone, target organs, physiological effect

Question 10

hormone function

Answer 10

-Hormones that regulate the production and secretion of another hormone are tropic hormones e.g thyroid stimulating hormone (TSH) secreted by the anterior pituitary stimulated thyroid gland to secrete thyroid hormones. Usually secreted from the hypothalamus.

• Hormones act directly on non-endocrine target are non-trophic hormones e.g thyroid hormones increase metabolic rate of cells

Question 11

Amine hormones

Answer 11

Hormones derived from modification of amino acids. COOH group removed.

Question 12

Peptide hormones

Answer 12

Derived from multiple amino acids linked to form an amino acid chain

Question 13

Steroid hormones

Answer 13

Derived from the lipid cholesterol, hydrophobic, must travel to target cells bound to a transport protein

Question 14

Hormone classes

Answer 14

hormones can also be grouped according to solubility. peptide and amines are hydrophilic while steroid hormones are lipophilic. The chemical nature of a hormone determines: how its’s synthesised, stored and released; how it is transported in blood; it’s biological half-life and mode of clearance and it’s cellular mechanism of action.

Question 15

peptide hormone synthesis

Answer 15

like usual polypeptide synthesis. A signal peptide is added and it goes into the golgi where it is stored in a vesicle. It travels from the cis to trans where it is processed. They are released where need be. As hydrophobic, needs exocytosis. 4 response, interact with membrane receptorr

Question 16

steroid hormone synthesis

Answer 16

hydrophilic therefore, cannot store in cell as they will easily diffuse out. Synthesised in SER, adrenal cortex, gonards, skin, placenta. When signal triggers the endocrine cells, precursors in the cytoplasm are rapidly converted into active hormone. Binding proteins protect from enzymatic degradation.