Endocrine Concepts

Question 1

paracrines

Answer 1

secreted by cells into ECF and affect neighboring target cells that are different than themselves.

Question 2

Autocrine

Answer 2

secreted by cells into ECF and affect same cells (self)

Question 3

cytokines

Answer 3

can be autocrine, paracrine, or endocrine hormones

Question 4

Classes of Hormones:

Polypeptides and proteins

Answer 4

• produced on ER
• preprohormones, cleaved to become prohormones
• Golgi apparatus for packaging into secretory vesicles and exocytosis, usually caused by increase in Ca++

Question 5

Classes of Hormones”

Steroids

Answer 5

• synthesized from cholesterol
• they are NOT stored
• lipid soluble
  
  • three cyclohexyl rings and one cyclopentyl ring
• large amounts of cholesterol in vesicles ready to mobilize

Question 6

Classes of Hormones:

Amine Hormones

Answer 6

• derived from Tyrosine
• Adrenal medulla hormones
  
  • epi and NE formed in medulla of adrenals
  • 4x more Epi than NE
  • stored in vesicles until release by exocytosis

Question 7

Classes of Hormones:

Thyroid hormones

Answer 7

• Synthesized and stored in thyroid gland
• With globulins which split and form the free hormones
• Then they bind to plasma proteins which release the hormone to target tissues
  
  • protein binding acts as reservoir

Question 8

Feedback loops

Answer 8

• Long feedback- hypothalamus to anterior pituitary to target organ and the target organ sends a message back to shut down.
• Short feedback- hypothalamus to anterior pituitary and back to hypothalamus
• Ultra short feedback- stays in hypothalamus

Question 9

What hormone is the only hormone with positive feedback?

Answer 9

Leutenizing Hormone

Question 10

Types of cyclical variation

Answer 10

• Periodic- monthly
• diurnal- daily
• seasonal

Question 11

Which types of hormones are water soluble and transported dissolved in plasma

Answer 11

peptides

catechols

Question 12

Which types of hormones are transported bound to plasma protein

Answer 12

steroid

thyroid

Question 13

Which hormones bind to a receptor on the surface of the cell membrane?

Answer 13

proteins

catechols

Question 14

Which hormones bind to the target cell receptor in the cell cytoplasm

Answer 14

steroids

Question 15

Which hormone binds at the target cell receptor cite in the cell nucleus?

Answer 15

thyroid

Question 16

How are receptors regulated?

Answer 16

• increased hormone concentration will cause a down regulation of receptors
  
  • caused by inactivation of some of the receptor molecules
  • inactivation of some of the intracellular protein signalingmolecules
  • temporary sequestration of the receptor to the inside of the cell, away from the site of action
  • destruction of receptors by lysosomes
  • decreased production of receptors

Question 17

Enzyme linked hormones

Answer 17

• Hormone binds to the outside of an enzyme
• catalytic binding site on inside
• enzyme is activated (sometimes inactivated) by hormone binding.

Question 18

Intracellular hormones and activation of genes

Answer 18

• lipid soluble hormones (such as steroid, thyroid, etc bind to receptors inside the cell instead of on membrane.
• once hormone has activated the hormone receptor complex, it binds directly to DNA and activates or represses transcription.
• **thyroid hormones activate directly with receptors in nucleus and increase metabolic activi

Question 19

Types of second messengers

Answer 19

cAMP

Calcium and associated Calmodulin

products of membrane phospholipid breakdown

Question 20

How does the Ca++ calmodulin system work?

Answer 20

1. Calcium enters cell (by ligand or changing membrane potential.)
2. Calcium ions bind with calmodulin
3. Calmodulin changes shape and activates or inhibits protein kinases

***Ca/calmodulin system is a 2nd messenger

Question 22

G_q

Phospholipase C Examples

(IP₃)

Answer 22

1. Gonadotropin releasing hormone
2. thyrotropin releasing hormone
3. growth hormone releasing hormone
4. corticotropin releasing hormone
5. angiotensin II
6. Antidiuretic hormone (V₁ receptor)
7. Oxytocin
8. Alpha- Andrenergic agonists

Going to go carefully agains all other advice.

Question 23

Adenylyl Cyclase

(cAMP) examples

Answer 23

1. Adrenocorticotrophic hormone
2. leutenizing hormone
3. follicle stimulating hormone
4. ADH (V₂ receptor)
5. parathyroid hormone
6. calcitonin
7. glucagon
8. B-Andrenergic agonists

Autumn leaves falling and preparing christmas gifts beautifully

Question 24

G Protein coupled recepts

IP₃

Answer 24

1. Ligand attaches to receptor on G protein
2. Alpha portion of G protein is released and activates Phospholipase C
3. Phospholipase C liberates diacycglycerol (DAG) and IP₃ from membrane lipids.
4. IP₃ mobilizes Ca⁺⁺ from the endoplasmic reticulum
   
   1. The Ca⁺⁺ and diacycglycerol (DAG) activate protein kinase C which phosphorylates proteins and causes specific physiologic actions

Question 26

Cytoplasmic/Nuclear Receptor (mostly steriods) examples

Answer 26

taking steriods can give you "roid rage" so \*insert NY accent\*... **PETTA C**an **C**urse **(d**irty..**)** * **P -** progesterone * **E -** Estradiol (estrogen) * **T -** Testosterone * **T -** Thyroid horomones (t3/t4) * **A-** Aldosterone * **C**an **-** Cortisol * **C**urse **(d**irty**) -** Calcitrol (vit D)

Question 27

Tyrosine Kinase examples

Answer 27

"**Tyrone kin**dly explained that he **likes** to be '**in da sun**'.. says it helps him **grow**" "in da sun" = Insulin " likes" = IGFs (insulin-like growth factors) "grow" = Growth horomones

Question 28

Guanalyate Cylase examples

Answer 28

"**A**nother **B**ad **N**ight **O**ut in **GUAM**" (all vasodialators:) * Another = ANP * Bad = BNP * Night Out = Nitric Oxide * in GUAM= sounds like **guan**alyate