Endocrinology

Question 1

what is a gland ?

Answer 1

A specialized group of cells or organ that secretes substances to be used or eliminated from the body

Question 2

What does the endocrine system do ?

Answer 2

A major regulatory system which uses hormones to produce homeostatic adjustments

Question 3

What are the 6 main functions of the endocrine system

Answer 3

1) maintain constant internal environment through the regulation of metabolism and H2O and electrolyte balance
2) acts as an adaptive stress response
3) used for growth and development
4) reproduction
5) creation of red blood cells
6) integrates with the autonomic nervous system in regulating both circulation and digestion

Question 4

What is a hydrophilic hormone ?

Answer 4

Is water soluble and have low lipid solubility and carry molecules within the plasma

Question 5

most hydrophilic hormones are usually what types?

Answer 5

peptide hormones ( short amino acid chain or hormones)
OR amines which are hormones based on single amino acid residues

Question 6

What are the 2 types of amine hormones ?

Answer 6

Catecholamines and thyroid hormones

Question 7

Hormone synthesis step 1

Answer 7

large precursor called preprohormones are synthesized by endoplasmic reticulum ribosomes

Question 8

step 2 Packaging

Answer 8

preprohormones are processed into active hormones as they travel through ER and Golgi complex. Preprohormones are packaged into secretory vesicles

Question 9

step 3 storage

Answer 9

hormone containing secretory vesicles are stored until cell receives appropriate signal

Question 10

step 4 Secretion

Answer 10

Appropriate signal initiates exocytosis of the vesicles and the hormones are released into the blood

Question 11

what are lipophilic hormones ?

Answer 11

highly soluble in lipids but poor in water and require a carrier molecule for transport in the body (amine thyroid and steroid hormones

Question 12

All steroid hormones are synthesized from ?

Answer 12

cholesterol molecule

Question 13

steroid and thyroid hormones are bound to ?

Answer 13

are bound to carrier molecules or proteins

Question 14

for hormones to achieve their desired effect they need to be ?

Answer 14

in an an unbound form to interact with target cell ( this is easy for catecholamines and hydrophilic hormones )
- lipophilic hormones require carrier molecules

Question 15

Peptide hormones and catecholamines bind to specific receptors located ?

Answer 15

located on the outer surface of plasma membrane of their target cells ( can’t cross through lipid bilayer )

Question 16

Steroid and thyroid hormones are lipophilic meaning they can do what ?

Answer 16

they can cross the plasma membrane and they can bind to receptors inside the target cells

Question 17

What happens after the binding to the receptor ? (peptide and catecholamines )

Answer 17

they. bind to surface receptors which activates secondary messenger systems in the cell and the initial signal gets amplified as low concentrations of hormone trigger response

Question 18

What happens when cAMP acts as a secondary messenger ? ( 4 steps)

Answer 18

1) extracellular messenger binds to a receptor activating G protein
2) Triggers the activation of adenyl cyclase molecules
3) activated proteins convert many molecules of ATP + (cAMP which activates protein kinase A
4) Activated kinase A enzyme phosphorylate and activate target proteins

Question 19

What happens when Ca 2+ acts as a secondary messenger ? ( 4 steps )

Answer 19

1) extracellular messenger binds to a receptor activating a G protein
2) this triggers several Phosphlipase C enzymes which convert PIP2 to IP3 and DAG
3) intracellular Ca2+ activates calmodulin
4) Ca 2+ camodulin complexes then activateCa 2+ dependent protein kinase ( caM kinase), which phosphorylate and activate target proteins

Question 20

Steps in lipophilic hormones and protein synthesis ( 6 steps )

Answer 20

1) lipophilic hormones diffuse across the plasma membrane and or the nuclear membrane to interact with intracellular receptors
2) hormone receptor complex (H-R) binds to the hormone response element within the DNA
3) DNA binding activates specific genes and produces messenger RNA ( mRNA )
4) mRNA leaves the nucleus
5) mRNA binds to a ribosome and proteins are synthesized
6) These newly synthesized proteins ultimately lead to the cellular response of the hormone

Question 21

What are the 4 major differences between neurotransmitter and hormones ?

Answer 21

1) Neurotransmitters belong to the nervous system while hormones area central component of the endocrine system
2) Neurotransmitters are transmitted across synaptic cleft , while hormones are transported through blood
3) Hormones are produced by endocrine glands while neurotransmitters are produced by neurons
4) Neurotransmitters travel shorter distances while may travel much greater distances

Question 22

Neural control response time vs endocrine control

Answer 22

Neural control is rapid while endocrine control is slow

Question 23

Duration of effects of neural control vs endocrine control

Answer 23

neural control has brief effects while endocrine effects persist long after stimulus

Question 24

number of targets of of neural control vs endocrine control

Answer 24

neural control is hard wired to one specific gland or muscle while endocrine has many different targets in tj body

Question 25

What is the role of the hypothalamus

Answer 25

controls hormone release and contains the supraoptic nucleus and the paraventricular nucleus

Question 26

how are the pituitary and the hypothalamus connected ?

Answer 26

axons of both supraoptic and paraventricular nucleus project downtime pituitary stalk and terminate on posterior pituitary

Question 27

how is the anterior pituitary connected to the hypothalamus ?

Answer 27

through the hypothalamic- hypophyseal portal system

Question 28

What happens when the hypothalamus releases hormones ?

Answer 28

the hormones get released into the portal system and are then carried directly to the anterior pituitary which will either inhibit or promote release of anterior pituitary hormones

Question 29

Hormones are synthesized in ?

Answer 29

the neuron cell bodies of the hypothalamus

Question 30

what happens after they are synthesized ?

Answer 30

the hormones are packaged into vesicles and are transported down the axons to nerve endings in the posterior pituitary

Question 31

When the appropriate stimulus reaches the hypothalamus what takes place

Answer 31

action potentials cause release of hormone vesicles into the blood

Question 32

Hormones that are released from the posterior pituitary ?

Answer 32

1- vasopressin (ADH) which enhances the retention of water by the kidneys and causes contraction of arteriolar smooth muscle
2- oxytocin : which stimulates contraction of the uterine smooth muscle cells during childbirth and promotes milk ejection in breast feeding

Question 33

Hormones released by the anterior pituitary (ALL PEPTIDE ) 6 total

Answer 33

1) growth hormone - responsible for body growth
2) adrenocorticotropic hormone (ACTH)- stimulates secretion of cortisol by the adrenal cortex
3) luteinizing hormone : ovulation and stimulates the secretion of estrogen and progesterone from ovaries
4) Thyroid stimulating hormone - stimulates release of thyroid hormones
5) follicle stimulating hormone: stimulates the development of the ovarian follicles and promotes secretion and estrogen in ovaries and sperm in males
6) Prolactin : enhances breast development and milk production (NOT TROPIC)

Question 34

what is the meaning of tropic

Answer 34

• once the hormone is released, they stimulate other endocrine glands to release their hormones

Question 35

all hormones of the anterior pituitary are tropic except ?

Answer 35

prolactin

Question 36

What is the hypothalamic- hypophyseal portal system ?

Answer 36

the vascular link between the hypothalamus and the anterior pituitary