Lecture 27

Question 1

What are Hormones?

Answer 1

Chemical messengers made from amino acids and cholesterol

Question 2

why do we need hormones?

Answer 2

• Homeostasis ( any process that living things do in order to actively maintain fairly stable conditions necessary for survival)
• metabolism
• development and growth
• body defenses (immunity and stress response)
• reproduction
• sleep

Question 3

What are the differences between water- soluble and lipid- soluble hormones

Answer 3

Chemical classification :
Water soluble- some amines (catecholamines) peptides and proteins
Lipid (fat) soluble- Some amines (thyroid hormones) steroids (cholesterol based)

Blood transport :
water soluble- dissolved
lipid (fat) soluble - bound to carrier protein

receptors:
water soluble- Cell (plasma) membrane
Lipid (fat) soluble- intracellular

different hormone actions:
water soluble activation of 2nd messengers to amplify hormone response
lipid soluble- alteration of gene transcription

response:

• Fast (milliseconds to minutes)
• Slow (hours to days)

Question 4

what are water solubles

Answer 4

Hormones that do not massively diffuse through the cell membrane, instead they bind to their receptors expressed on the extracellular surface of the target cell membrane

Question 5

what are lipid solubles

Answer 5

Lipid-soluble hormones easily diffuse through the cell membrane. Steroid hormones are the most common circulating lipid-soluble hormones.

Question 6

what is the hypothalamus

Answer 6

• made of neurons
• involved in control of many other hormones
• neural link to endocrine system

this is where the major connection point between the nervous system and the endocrine system begins at the hypothalamus

Question 7

where is the hypothalamus

Answer 7

In the brain, in the middle under the actual brain

Question 8

how does the hypothalamus link the neural and endocrine systems together

Answer 8

trough the poster and anterior pituitary glands

Question 9

what are the differences between the hypothalamic connection to the posterior vs anterior pituitary gland

Answer 9

the posterior pituitary= axon connection
posterior pituitary hormones made in hypothalamus

• travel down axons
• then stored in axon terminals
• action potentials cause hormone release from posterior pituitary

anterior pituitary= blood vessel connection
releasing/ inhibiting hormones made in hypothalamus

• travel in blood
• to affect anterior pituitary cells
• to release or inhibit release of anterior pituitary hormones