Endocrine

Question 1

Nonspecific binding protein

Answer 1

located in the cytoplasm and used by T3 as a stepping stone to enter the nucleus where T3 can bind to ligand-binding domain at the receptor

Question 2

What is the difference between steroids and thyroid binding

Answer 2

• Thyroid hormone receptors are located in the nucleus and bind to DNA even in the absence of thyroid hormone ligands, corepressors are recruited if its absent
• one half side of thyroid hormone response elements binds to T3 another to vitamin A derivatives

Question 3

Where do coactivators and corepressors bind?

Answer 3

• Not the DNA, buy the receptor pockets different from the ligand binding domain for the hormone
• binding of the steroid ligand to a nuclear receptor binding domain recruits coactivators and changes its shape

Question 4

What hormones make use of homodimers? Which ones use Heterodimers?

Answer 4

• Homodimers: Steroids

- Heterodimers: T3 and retinoic acid

Question 5

Origin, Location and Binding of Corticosteroids

Answer 5

• Adrenal Cortex
• Cytoplasm
• move towards the nucleus post binding, then bind to hormone receptor elements in the regulatory region of target genes

Question 6

Mechanisms of Steroid Hormone Action

Answer 6

• Stimulation of gene transcription; ~ 30 min
• Nongenomic action occurs when a steroid binds to a receptor on the plasma membrane activating second-messenger system
• Distribution of receptors within the cell varies by tissue and hormone

Question 7

Prehormone

Answer 7

Molecules like thyroxine; secreted by endocrine glands , but inactive until converted to an active hormone in the Target Cell

Question 8

Activation of lipophylic hormones

Answer 8

Receptor has to bind to the hormone ligands before being allowed to bind to a specific DNA region; hormone response element

Question 9

Nonpolar (Lipophilic) mechanisms of Action

Answer 9

• Pass easily through the plasma membrane and bind to the receptors within the nucleus or cytoplasm
• Delivered to target cells via carrier proteins in blood
• two domains: Hormone and DNA binding one on the receptors

Question 10

Polar ( hydrophilic) mechanisms of action

Answer 10

• bind to receptors on the plasma membrane
• use second-messenger system
• carried by blood

Question 11

Steroid hormone that is active in some tissue, but converted to another one in other tissues in order to activate`

Answer 11

Testosterone to DHT

Question 12

Prohormone

Answer 12

• Precursor of hormones consisting of peptide hormones synthesized together; minimal hormonal effects on its own
• cut and splices within a gland to make a hormone

Question 13

Catecholamine

Answer 13

• water soluble

- epinephrine and norepinephrine

Question 14

Two types of hormones

Answer 14

• polypeptide and glycoproteins
• would be broken down and digested into inactive form
  Example: insulin

Question 15

2 endocrine glands that secrete steroids and what types

Answer 15

• Adrenal cortex (coritcosteroids: cortisol and aldesterone)

- Gonads:: Sex steroids

Question 16

What glands release Amines?

Answer 16

Adrenal medulla, thyroid and pineal glands

Question 17

How many amino acids to polypeptide and protein hormones have? Examples

Answer 17

`100+ EACH, GH and insulin

Question 18

What is a glycoprotein and an example of one

Answer 18

protein and a carbohydrate : FSH

Question 19

Neurotransmitters

Answer 19

• diffuse across a narrow synaptic cleft to cell outer membrane
• Most hormones can also function as neurotransmitters if present in a different organ
• Require proteins that combine with a regulatory molecule; the change will provoke a specific set of change; there is a mechanism to turn off the action of the regulator

Question 20

Synergistic hormonal interaction

Answer 20

2 hormones work together to produce a particular effect that’s

• Additive: epinephrine and norepinephrine raise HR; together the increase is greater
• Complementary: E + cortisol + prolactin + oxytoccin each promote lactation, but have different functions

Question 21

Permissive Hormonal Interaction

Answer 21

• Enhances the responsiveness of a target organ to the second hormone or increase its activity:

Presence of Estradiol within the uterus, induces the formation of progesterone receptor proteins

Question 22

Antagonistic hormonal interaction

Answer 22

• high concentration of a hormone inhibits the secretion of another

During pregnancy estrogen inhibits production of prolactin

Insulin and glucagon have opposite effects: promotes fat formation/breakdown

Question 23

Hormone concentration and tissue response

Answer 23

• depends primarily on the rate of secretion by endocrine glands or administration
• hormones do not accumulate in the blood, organs like liver use enzyme to convert them to more water soluble compounds then excrete them
• subsequent administration expresses greater response

Question 24

Desensitization and downregulation

Answer 24

• Prolonged exposure to high concentrations of polypeptide hormone desensitizes the target cells
• down-regulation of receptor decreases their number partially causing desensitization
• administration in spurts prevents receptor downregulation

Question 25

4 hormones that promote fat catabolism

Answer 25

• epinephrine
• cortisol
• thyroxine
• GH

Question 26

3 levels of implementing hormonal effects

Answer 26

• autocrine ( controls changes within the same cell)
• paracrine ( nearby cells)
• endocrine (bloodstream to Target Cell)