Intro

Question 1

ENDOCRINE GLAND

Answer 1

Group of cells which secrete “messenger” molecules directly into bloodstream

Question 2

HORMONE

Answer 2

Bioactive “messenger” molecule secreted by an endocrine gland into blood

Question 3

ENDOCRINE hormones act on target cells…

Answer 3

at a distance from source

Question 4

PARACRINE hormones act on target cells…

Answer 4

nearby

Question 5

AUTOCRINE hormones have an effect on

Answer 5

its own immediate source

Question 6

Endocrine effects take place over a

Answer 6

Long time-span: seconds to days

Question 7

Types of hormone

Answer 7

1. Protein/polypeptide/ amino acid derived 2. Steroid hormones3. Miscellaneous

Question 8

Protein hormone synthesis

Answer 8

AAs in blood -> cellA signal allows DNA to be transcribed to produce relevant mRNATranslation of mRNA to prohormone in RERProhormone –> GolgiIn Golgi, further processed into vesicles with proteolytic enzymes that can cleave prohormone to form active hormone

Question 9

Which blood vessels are pituitary hormones secreted into?

Answer 9

Pituitary capillary

Question 10

Example of protein hormone

Answer 10

Adrenocorticotropic hormone (ACTH)

Question 11

Prohormone of ACTH

Answer 11

POMC

Question 12

Example of Steroid hormone

Answer 12

Cortisol

Question 13

Steroid hormone synthesis

Answer 13

LDL in blood–> cell by endocytosisCholesterol split from lipoprotein- esterified and stored in cytoplasmic vacuoles as fatty acid estersEsterase enzyme liberates cholesterol from fatty acid estersSTAR protein (Steroidogenic acute regulatory protein) drives cholesterol into mitochondriaEnzyme pathway in mitochondria generates steroid hormone

Question 14

Why does cholesterol need to enter the mitochondria?

Answer 14

All enzymes that produces steroid hormone are in the mitochondria

Question 15

Where are protein hormones stored?

Answer 15

In vesicles within the cell that produced themSecreted when required

Question 16

Where are steroid hormones stored?

Answer 16

In bloodstream

Question 17

If a steroid hormone is heavily plasma protein bound, can it still access tissues?

Answer 17

YesThere’s always a small proportion of free hormone that can move in to cells when required (“Active pool”)

Question 18

How are steroid hormones stored in the blood?

Answer 18

Majority are bound to plasma proteins (general or specific)There is a small ‘active pool’ unbound

Question 19

Bound & Free steroid hormones are in…

Answer 19

Dynamic equilibrium

Question 20

Most target cells of protein hormones have…

Answer 20

a receptor to recognise relevant hormone

Question 21

Mechanism of protein hormone e.g. ACTH

Answer 21

n

Question 22

Why don’t steroid hormones need receptors on their target cells?

Answer 22

They are very lipid solubleFree hormones diffuse across plasma membrane into cell

Question 23

Location of steroid hormone target

Answer 23

Intracellular

Question 24

Steroid hormone mechanism

Answer 24

Steroid hormone diffuses into target celland binds to target receptorSteroid receptor complex translocates to nucleus to up/down regulate protein transcription and translation

Question 25

Why would an endocrine system be described as “acting like a thermostat”?

Answer 25

Most have a closed loop feedback