Diabetes & Endocrinology (Introduction to the Endocrine system)

Question 1

define the term endocrine system

Answer 1

a collective term for the cells which produce chemical messenger substances that are
regarded as hormones

Question 2

what are paracrine chemicals

Answer 2

act local to the site of synthesis do NOT travel to distant sites

Question 3

what are autocrine chemicals

Answer 3

act on/in the same cell that synthesises the hormone

Question 4

what are exocrine chemicals

Answer 4

released from exocrine glands via ducts to the external environment

Question 5

how to endocrine hormones arrive at their target organ

Answer 5

travel in the blood

Question 6

autocrine cells secrete chemicals that bind to receptors, where are the receptors located

Answer 6

the receptors are on the same cell

Question 7

paracrine cells secrete chemicals, where do these chemicals have their effect

Answer 7

paracrine cells secrete chemicals that diffuse in ECF to affect neighbouring cells

Question 8

what are some of the principal endocrine glands in the body

Answer 8

hypothalamus
pituitary gland
thyroid gland
parathyroid gland
adrenal gland
kidney's
ovary and testis

Question 9

what are the features of endocrine hormones

Answer 9

1. secreted from cells into blood
2. transported via the blood to distant targets
3. exert their effects at very low concentrations

Question 10

what are the 3 classes of endocrine hormone

Answer 10

peptide or protein (most common)

steroid (all derived from cholesterol)

amine hormones

Question 11

what 2 amino acids are all amine hormones derived from

Answer 11

tryptophan (only melatonin)

tryosine

Question 12

what are preprohormones

Answer 12

preprohormones are the precursor proteins to one or more prohormones

Question 13

what are prohormones

Answer 13

prohormones are precursors to peptide hormones

Question 14

where are preprohormones produced

Answer 14

ribosomes

Question 15

prehormones are cleaved into smaller units to produce prohormones, where does this happen

Answer 15

RER

Question 16

where do prohormones and proteolytic enzymes get packaged together

Answer 16

golgi apparatus

Question 17

what is C peptide

Answer 17

the inactive fragment cleaved from the insulin prohormone

Question 18

why would the levels of C-peptide in plasma or urine be measured

Answer 18

this can indicate endogenous insulin production levels from the pancreas

Question 19

what is metabolised faster C-peptide or insulin

Answer 19

insulin (about 5x faster)

Question 20

what is the solubility of peptide proteins

Answer 20

water soluble

Question 21

peptide hormones cannot cross the cell membrane so where are the receptors they bind to

Answer 21

receptors are located on the membrane of the target cell

Question 22

peptide hormones work by modulating two pathways name these pathways

Answer 22

GPCR

tryosine kinase linked

Question 23

a peptide hormone can bind to a GPCR on the cell surface what effect will this have

Answer 23

2nd messenger system activation which leads to modification of an existing protein

(this is a rapid response)

Question 24

a peptide hormone can bind to the cell surface and activate a tyrosine kinase linked receptor, what effect will this have

Answer 24

alter gene expression

this is slower but longer lasting activity

Question 25

when are steroid hormones synthesised

Answer 25

directly as needed compared to other hormones which are stored then released

Question 26

why are steroid hormones synthesised only when needed

Answer 26

they are highly lipophillic so cannot be retained within lipid membranes and would just diffuse into the blood immediatly

Question 27

steroid hormones are poorly soluble in water so how are they transported

Answer 27

transported bound to carrier proteins such as albumin

this stabilizes their transport through the plasma

Question 28

what endocrine organs produce steroid hormones

Answer 28

gonads (testes/ovary)
placenta
kidney
adrenal cortex

Question 29

where are the receptors for steroid hormones located

Answer 29

inside cells (as they are lipophillic)

Question 30

when a steroid hormone binds to its receptor what does it trigger

Answer 30

either activation or repression of gene function within the nucleus (=genomic effect)

Question 31

what amine hormone are most amino acids derived from

Answer 31

tyrosine

Question 32

give examples of amine hormones

Answer 32

dopamine
noreoinephrine
epinephrine

Question 33

what is the only amine hormone not derived from tyrosine

Answer 33

melatonin (derived from tryptophan)

Question 34

what is the function of melatonin

Answer 34

regulates circadian rhythm

Question 35

what types of hormone are water soluble

Answer 35

peptide

catecholamines

Question 36

how long is the half life of peptide and catecholamine hormones

Answer 36

they both have a short half life usually minuets

Question 37

what is the definition of half life

Answer 37

time taken for plasma concentration to fall by half

Question 38

what is the half life of steroid hormones

Answer 38

longer half life usually hours to days

Question 39

steroid and thyroid hormones need hormone carrier proteins, why

Answer 39

steroid and thyroid hormones are lipophillic

it increases solubility which is required for blood mediated transport

it protects them from degradation by increasing their half life

Question 40

how is a hormone removed form circulation

Answer 40

via excretion or metabolic transformation

Question 41

steroid and thyroid hormones take hours or days to excrete or metabolise why is this

Answer 41

because they are protein bound

Question 42

what does permissive effect refer to

Answer 42

the presence of one hormone enhancing the effect of another e.g TH and epinephrine