Hormone structure and action

Question 1

What are the forms of chemical communication?

Answer 1

• autocrine
• neurocrien
• paracrine
• endocrine
• pheromone
• allomone

(more distant effects as you go down)

Question 2

What is autocrine communication?

Answer 2

chemical released by cell affects its own activity

Question 3

what is neurocrine (synaptic) communication?

Answer 3

chemical released by neuron diffuses across synaptic cleft and affects postsynaptic membrane. Affects a different cell but a cell that is directly connected.

Question 4

What is paracrine communication?

Answer 4

chemical released into extracellular environment and affects nearby target cells

Question 5

What is endocrine (hormone) communication

Answer 5

chemical released into bloodstream and selectively affects (distant) organs

Question 6

what is pheromone communication?

Answer 6

chemical released into external environment and affects conspecifics (members of the same species)

Question 7

what is allomone communication?

Answer 7

chemical released into external environment and affects heterospecifics (e.g. pollination)

Question 8

What are hormones?

Answer 8

• bioregulators of the endocrine system
• secreted by specialised cells directly into the blood
• selectively act on target cells

Question 9

Where are hormones produced?

Answer 9

endocrine cells and secreted into the bloodstream

Question 10

What are the three main types of hormones?

Answer 10

protein,
amine,
steroid

Question 11

What are protein hormones?

Answer 11

• oxytocin
• vasopressin
• insulin….

chain of amino acids

Question 12

where are most protein hormones released from?

Answer 12

hypothalamus

Question 13

Which is bigger, amine or protein hormones?

Answer 13

amine are smaller and simpler than protein hormones

Question 14

How do hormones travel?

Answer 14

• Hormones travel around the blood stream and affect cells with the correct receptor.
• They bind to that receptor. Protein and amine hormones bind to a receptor and do not go in the cell.
• The receptor releases a chemical (secondary messenger) within the cell.
• The secondary messengers alter the function of the cell.

Question 15

Where do protein and amine hormones bind?

Answer 15

outside of cells and act raplidly

Question 16

how can you alter the sensitivity of protein and amine hormones

Answer 16

• Sensitivity can be altered by increasing (upregulating) or decreasing (downregulating) numbers of receptors on cell

Question 17

What are steroid hormones?

Answer 17

Derived from cholesterol
Made from four interconnected carbon rings
Soluble in lipids. Can dissolve in fats. Means they are able to corss the cell membrane.

Question 18

What are the cell membranes in steroid hoemones made from

Answer 18

Cell membrane is made of lipids so steroid hormones can dissolve through and pass to the other side of the membrane. They then have to bind to the specific receptor type for that steroid hormone. If the cell contains this receptor, it will bidn and this will create a steroid receptor complex. This steroid receptotr complex travels to the nucleus and binds to the DNA that then alters the production of proteins.

Question 19

info about steroid hormones

Answer 19

• Act on specific receptors inside cells
• Act ‘slowly’ (hours)
• Have long-lasting effects via transcription of DNA
• Sensitivity can be altered by presence or absence of co-factors necessary for cells to respond
• Cannot be stored—must be synthesised on demand

Question 20

what do endocrine glands do?

Answer 20

Endocrine glands secrete the hormones and they are composed of endocrine cells. These cells secrete hormones in the interior space in the cell. The hormone passes directly into the blood stream from the endocrine cell.

Endocrine glands are referred to as ductless. This is opposite to exocrine glands (e.g. sweat glands)

Question 21

What controls hormone production?

Answer 21

• Hormone production needs to be constantly managed
• Feedback loops play a key role
• Usually involves negative feedback: high levels of hormone inhibit production of hormone → maintains homeostasis
• Sometimes involves positive feedback
• e.g. oxytocin secretion in milk letdown reflex

Question 22

what are the key pathways in hormones?

Answer 22

• autocrine feedback
• target cell feedback
• brain regulation
• brain and pituitary regulation

Question 23

What is autocrine feedback?

Answer 23

This cell produces the hormone

Question 24

What is target cell feedback?

Answer 24

Endocrine cell produces a hormone that changes activity of target cell. The negative feedback happens because of that biological response.