Introduction to the Endocrine System

Question 1

Autocrine
Paracrine
Endocrine
Neuroendocrine

Answer 1

• secretion affects self or cell of similar type
• secretion affects neighbor cell
• secretion affects target further away (via bloodstream)
• Neuron itself releases secretion into bloodstream

Question 2

What are special endocrine cells and hormones?

Answer 2

Some cells are within organs (like adipose, heart etc.) and release hormones
-some hormones get converted in the bloodstream (e.g. angiotensin II and vitamin D)

Question 3

Draw out what hormones the hypothalamus, anterior, posterior pituitary, thyroid and parathyroid glands release

Answer 3

Ok

Question 4

Draw out the products of the various endocrine glands

Answer 4

Ok

Question 5

Properties of peptide/protein hormones

Answer 5

Protein is >100 amino acids long
Water soluble
Membrane receptor
Stored in vesicles

Question 6

Properties of steroid hormones

Answer 6

Precursor is cholesterol
Lipid soluble
Nuclear receptors

Question 7

Properties of amine hormones

Answer 7

Derived from tyrosine (can be water or lipid soluble)

Question 8

Describe how protein/peptide hormones are created

Answer 8

Preprohormone (not functional) > ER (turned to prohormone) > vesicle packing and release > cleaved to functional hormone

Question 9

How are hormones released from storage?

Answer 9

Intracellular Ca2+ increase > cAMP and PKA activation > vesicles with hormone released into bloodstream

Question 10

Structure of the steroid hormones

Answer 10

4 rings structure (like cholesterol)

Modified side chains

Question 11

Which glands produce steroid hormones?

Answer 11

Adrenal cortex, gonads, Placenta, corpus luteum

*AC and reproductive organs

Question 12

What are the two groups of amine hormones?

Answer 12

Catecholamines

Thyroid hormones

Question 13

What are the properties of catecholamines? What hormones are catecholamines?

Answer 13

• made in cytosol granules. Targets are on membrane

- Epinephrine/norepinephrine and dopamine

Question 14

What are the properties of thyroid hormones?

Answer 14

• stored in gland lumen as thyroglobulin

- target nuclear receptors

Question 15

Broadly,at what level are hormones regulated?

Answer 15

Synthesis, secretion or circulation

Question 16

How does hormone protein binding correlate with hormone half life?

Answer 16

Higher binding = higher half life = lower clearance rate

Question 17

What is the significance of binding proteins?

Answer 17

Most hormones are bound to binding proteins and are inactive/ Just have to detach from binding protein to activate. Serve as reservoir for when active hormones are depleted.

Question 18

How exactly can you regulate hormone secretion?

Answer 18

Neural control (neuron instructs release of hormone)
Feedback control (product comes back and + or - release of more hormone)

Question 19

What is positive feedback?

Answer 19

Hormone product comes back and tells maker to make more. Usually leads to explosive event like ovulation or childbirth

Question 20

What is negative feedback?

Answer 20

Hormone product comes back and tells maker to stop making more hormones (balancing levels)

Question 21

What is long loop feedback?

Answer 21

3rd tier feeds back to 1st and 2nd tier (e.g. thyroid gland feeds back to hypothalamus and pituitary)

Question 22

What is short loop feedback?

Answer 22

2nd tier feeds back to first tier (TSH feeds back to hypothalamus)

Question 23

What is ultra short loop feedback?

Answer 23

Gland inhibits itself

Question 24

Draw the 5 major endocrine axes (include the tiers)

Answer 24

Ok

Question 25

What are the regulators of hypothalamus activity?

Answer 25

Suprachiasmatic nucleus Pineal gland Physiological stress

Question 26

How does the suprachiasmatic nucleus work?

Answer 26

It receives info from various parts of the body about day and night info and tells hypothalamus what to do using this info

Question 27

How does the pineal gland regulate the hypothalamus?

Answer 27

Pineal releases melatonin. This feedbacks to SCN (tells it it's night time, hypothalamus do night time things!)

Question 28

How can hormones be regulated using their receptors

Answer 28

1. Changing (up/downregulation) the number of receptors (if too much hormone, decrease the receptors to not overwhelm the system. If too little hormone, increase the receptors to increase the chance hormones bind and do its effect) 2. Changing the affinity of receptor to hormone

Question 29

Draw the adenylyl cyclase pathway

Answer 29

Ok

Question 30

What hormones use the adenylyl cyclase pathway?

Answer 30

ACTH, LH, FSH, TSH, glucagon, ADH (v2 receptor), HCG, CRH, calcitonin, PTH, beta receptors

Question 31

Draw the mechanism of action of PLC pathway

Answer 31

Ok

Question 32

What hormones use the PLC pathway?

Answer 32

GnRH, TRH, oxytocin, GHRH, Angiotensin II, ADH (v1 receptor), alpha 1 receptors

Question 33

Describe the mechanism of action of steroid hormones

Answer 33

Ok

Question 34

What hormones use the steroid hormone mechanism?

Answer 34

All the hormones released by AC, vitamin D and thyroid hormones

Question 35

What type of receptors does the guanylyl cyclase pathway use

Answer 35

1. ANP (extracellular domain receptor, GC is membrane bound) 2. NO (intracellular domain receptor, GC is soluble)

Question 36

What hormones use the guanylate cyclase mechanism?

Answer 36

ANP | NO

Question 37

Draw the mechanism of the guanylyl cyclase pathway

Answer 37

Ok

Question 38

What is the difference between receptor tyrosine kinase and tyrosine kinase-associated receptors?

Answer 38

Receptor tyrosine has its own tyrosine kinase activity Tyrosine kinase associated receptor associates with a second protein that has kinase activity >>>> both result in downstream phosphorylation

Question 39

What hormones use the tyrosine kinase mechanism?

Answer 39

Insulin, IGF-1, growth hormone, prolactin

Question 40

Review the table of hormone functions

Answer 40

Ok