Endo-Intro- Intro Slides

What is endocrinology?

study of hormones and their actions

the endocrine system consists of hormones that travel through what?

blood

What is an organic chemical which is released by living cells that travels through the blood to trigger physiological changes?

a hormone

T/F: cells are only affected by a specific hormone if they have the correct receptor that corresponds to that hormone

true

What two things can change how effective a hormone is?

1. Concentration of hormone in blood

2. how receptive the target cell is (lot or a little receptors on cell)

What are the two types of hormone receptors?

Which hormones, either lipid-soluble or water-soluble, are associated with each?

1. transmembrane proteins- water soluble

2. Intracellular receptors - lipid-soluble

What does "up-regulation" mean in relation to hormone adaptation?

# of receptors on a cell is increased, causing higher sensitivity even when hormone levels are low in the bloodstream

What does "down-regulation" mean is relation to hormone adaptation?

# of receptors on a cell is DECREASED, causing cells to be LESS sensitive to the hormone (even if the hormone is in excess in the blood stream)

What are the main endocrine glands of the body? (9)

1. Hypothalamus

2. Pituitary gland

3. Pineal gland

4. Thyroid gland

5. Parathyroid gland

6. Thymus

7. Pancreas

8. Adrenal glands

9. Gonads (ovaries/testes)

What are the three molecular types of hormones?

1. Peptide/Protein Hormones

2. Steroid hormones

3. Amines

Which type of hormone is water-soluble?

Are these fast or slow acting?

Peptide/Protein Hormones

Fast-Acting (can travel through blood easily)

Which type of hormone is lipid-soluble?

Are these fast or slow acting?

Steroid hormones

slow acting (require a transport protein to get through bloodstream. )

Most peptide/protein hormones use what type of cell receptors?

transmembrane receptors

Steroid hormones utilize which type of cell receptor?

intracellular receptors

Which hormones are released via diffusion?

Which are released via vescicles and exocytosis?

Steroid hormones

Peptide/Protein Hormones

Steroid hormones are derived from __________________.

cholesterol

T/F: Amines are only lipid-soluble hormones.

FALSE- they can be water or lipid-soluble depending on the hormone!

T/F: the endocrine system is ductless (closed system).

TRUE (doesn't leave the body)

Steroid hormones are fat lovers. What are two other terms for "fat lovers"?

lipophilic

hydrophobic

Most peptide/protein hormones are water lovers. What are two other terms for "water lovers"?

Hydrophilic

lipophobic

What do autocrine hormones act on?

the same cell that secreted them (act on itself)

What do paracrine hormones act on?

neighboring cells

what do endocrine hormones act on?

How do they achieve this?

-act on a cell far from the secreting cell (original cell)

-hormone travels through lymph or the blood stream to achieve this

What are the circulating hormone/s?

What are the local hormone/s?

circulating: Endocrine hormones

local: autocrine and paracrine hormones

What are the three ways that cells are stimulated to secrete hormones? TQ

1. Hormonal (chemical in nature)

2. Humoral (sensor associated with the gland itself)

3. Neural (generates rapid release of hormone)

T/F: Hormone secreting cells wait until they receive a stimulus to start building hormones.

FALSE: they do NOT wait, and hormone is typically made and stored already in cell.

Which type of hormone utilizes exocytosis (storage compartment moving to the cell's plasma membrane) to be released from the cell?

Protein/Peptide Hormones

Which type of hormone utilizes diffusion to be released from a cell?

Steroid hormones

Lipophilic (hydrophobic) hormones utilizes what to move through the bloodstream to their target tissue?

Transport proteins

What is the "half-life" of a hormone?

time required for half the concentration of the hormone to be degraded

What are direct transport routes and what are 2 major examples of these routes?

-Routes that are developed to ensure important hormones reach their targets without being degraded.

- Btw the Hypothalamus and anterior pituitary

-Btw hepatic portal circulation (portal vein between GI/Spleen and the liver directly for insulin and glucagon regulation)

The removal of hormones from circulation is called what?

metabolic clearance

What are the different fates of a hormone after being released into circulation? (3)

1) bind to specific receptor in target organ

2) Undergo metabolic transformation by the liver

3) undergo urinary excretion

Hormones are divided into 2 types of messengers.

What is the difference between primary and secondary messengers?

Primary messengers: hormone itself travels to create a cell response.

Secondary messenger: hormone causes the cell to release proteins, and these proteins act as a second messenger to create a response.

Which hormones can act as primary messengers and why?

Steroid hormones- they can bring intracellularly and do not require additional proteins to DIRECTLY influence transcription/translation within a cell.

Which hormones typically require secondary messengers and why?

Protein/Peptide hormones- they bind on the outer cell membrane, triggering a cascade inside the cell and rely on proteins within the cell.

What are the 3 potential effects/physiologic actions that hormones can have?

1. Kinetic effects (ex: muscle movement)

2. Metabolic effects (ex: change of speed of cellular process)

3. Morphogenetic effect (ex: increased or decreased cell growth in embryo development)

T/F: The adenylyl cyclase mechanism utilizes a second messenger.

TRUE (uses Cyclic AMP)

What is the second messenger found in the Adenylyl Cyclase mechanism?

cAMP

What are the second messengers of the Phospholipase C mechanism?

-IP3

-DAG

-Ca2+

What are the steps of a steroid hormone mechanism? (kinda long card)

1. lipid soluble hormone diffuses through cell membrane

2. Hormone binds with intracellular receptor, forming a hormone-receptor complex

3. Complex enters the nucleus and triggers gene transcription

4. Transcribed mRNA is translated into proteins that alter cell activity

What are the steps of a Tyrosine Kinase Mechanism?

(image with card)

1. extracellular binding occurs with ligane (hormone) on transmembrane protein containing tyrosine kinase

2. Intracellular tyrosine kinase self-phosphorylates and also phosphorylates other proteins inside the cell

3. phosphorylated (activated) proteins lead to a cascade of events, altering cell activity

What is the second messenger in the Guanylate cyclase mechanism?

cGMP

In what two ways are the secretions of hormones regulated?

1. negative feedback loops (hormone secretion inhibits its own production)

2. positive feedback loops (secretion of hormone stimulates more production of a hormone)

NOTE: some hormones are not regulated by feedback loops, but rather sudden bursts of secretion that only lasts a few seconds-minutes

What is the most common form of regulation of hormones?

negative feedback loops

Describe the physiological response-driven negative feedback loop

Circulating component-->endocrine gland--> hormone--> target tissue--> phsiologic effect

Describe the endocrine axis-driven feedback loop

Hypothalamic neuroendocrine neurons--> releasing hormone-->Pituitary gland-->trophic hormone--> peripheral endocrine gland--> Hormone--> target organ--> physiologic effects

In the endocrine axis driven feedback loop, what are the primary, secondary and tertiary parts when referencing the parathyroid hormone.

Primary- Endocrine Gland (thyroid gland)

secondary- pituitary gland

tertiary- hypothalamus

What is an agonist?

molecule binds to a receptor and causes biologic response in the cell

What is an antagonist?

molecule binds to a receptor and blocks the binding of an agonist=no action caused

What is primary hyposecretion?

What is secondary hyposecretion

primary- too little hormone secretion by the endocrine gland

secondary-endocrine gland receiving too little of its tropic hormone (pituitary)

What is primary hypersecretion?

What is secondary hypersecretion?

primary- too much hormone secretion by the endocrine gland

secondary- endocrine gland receiving too much of its tropic hormone

What is hyporesponsiveness?

target cell does not respond normally to hormone (under responds)

What is hyperresponsiveness?

target cell has excessive response to the hormone