Endocrine System

Question 1

Endocrine glands

Answer 1

Exocrine- secrete products onto epithelial surfaces via ducts (has tubes)
Endocrine- secrete products into interstitial fluid (tubeless)

Question 2

Examples of endocrine glands

Answer 2

Pituitary, thyroid, parathyroid

Question 3

Roles of hormones

Answer 3

Present in very low concentrations.

Strongly regulated-the amounts present make a huge difference.

Question 4

What do hormones do

Answer 4

1. Help regulate (chemical composition, metabolic and energy balance, concentration of smooth and cardiac muscle, glandular secretions, immune system activities)
2. Control growth and development
3. Regulate the operation of reproductive systems
4. Help establish cycles (ie: day&night)

Question 5

Hormone activity

Answer 5

Hormones affect specific targets with specific receptors

• down regulation( makes receptors less sensitive)
• up regulation(makes receptors more sensitive)

Question 6

Types of hormones

Answer 6

Hormones travel in the blood and act on distant target cells.
Paracrine- act on neighbouring cells
Autocrine- act on the same cell that secreted them
Interleukin- example of both paracrine and autocrine

Question 7

Chemical classes of hormones

Answer 7

Lipid soluble and water soluble

Question 8

Water soluble hormones

Answer 8

Amine, peptide/protein, eicosanoid
Circulate freely in blood.
They use channels (in this case “extracellular receptors”) to get through the the lipid bilayer

Question 9

Lipid soluble hormones

Answer 9

Steroid, thyroid, nitric oxide
Carried by transport proteins in blood.
When it gets close to the membrane they diffuse through the membrane and target receptors (intracellular receptors)

Question 10

Transport proteins

Answer 10

1. Transport hormones in blood
2. Slow the rate of hormone loss in urine
3. Provide a hormone reserve in blood

Question 11

Roles of the endocrine system

Answer 11

Hormones- meditator molecule released in one part of the body but regulates activity of cells in other parts.
It has slower responses, the effects last longer, as effects more at once

Question 12

Lipid soluble hormones- typical mechanism of action

Answer 12

1. Lipid soluble hormone diffuses into the cell
2. Binds to the receptor and activates the hormone complex receptor and alters gene expression. (DNA gets told to make a new protein which makes mRNA)
3. Newly formed mRNA directs synthesis of specific proteins on ribosomes
4. New proteins alter the cells activity

Question 13

Water soluble hormones - typical mechanism of action

Answer 13

1. Extracellular receptor activates “G protein”
2. G protein activates an enzyme (converts ATP to cAMP)
3. cAMP activates a protein
4. The protein activates enzymes
   5 enzymes catalyze reactions producing the cells responses to the hormone