Endocrine system I - Hormones

Question 1

Examples of neurontransmitters;

Answer 1

noradrenaline
acetylcholine

Question 2

Examples of neuroendocrine

Answer 2

Oxytocin & ADH

Question 3

Examples of endocrine

Answer 3

Insulin
TSH
Thyroxine
Cortisol

Question 4

Intracellular messages systems: simple step by step

Answer 4

Secreting cell > Blood vessel > target cell (neurotransmitter gets transferred)

Question 5

From secreting cell >target cell. What is this type of regulation called?

Answer 5

Paracrine

e.g. glucagon, somatostatins

Question 6

Autocrine =

Answer 6

chemical released by same cell is taken in by its own use - own function

e.g. prostaglandins

Question 7

What are hormones + example;

Answer 7

chemical substances that act like messenger molecules in the body

e.g.
GIT
Thymud
Adipocyte
Placenta
Kidney
Heart

Question 8

Properties and functions of hormones;

Answer 8

1) “yo arouse” or “excite”
2) glands secretes hormones directly into blood stream (ductless)
3) Carried to target cells/tissure (away from endocrine gland - INTERNAL to body)

Question 9

Endocrine gland

Answer 9

Sylvia gland
Internal to the body
Function - secrete hormone

Question 10

List 4 types of hormone=

Answer 10

1. Peptide hormones
2. steroidal hormones
3. Tyrosine containing hormone
4. Eicosanoids

DIFFERENT - [structure, storage, transportation, function]

Question 11

List 4 types of hormone=

Answer 11

1. Peptide hormones
2. steroidal hormones
3. Tyrosine containing hormone
4. Eicosanoids

DIFFERENT - [structure, storage, transportation, function]

Question 12

1. Peptide hormones

Size and structure
Location of secretion
Synthesis
Release
Transport

Answer 12

Chemical structure : chains of amino acids
[small chains e.g. TRH: contains 3aas / large chains e.g. LH/FSH 80aas]

Mostly secreted from hypothalamus, pituitary, pancreas and GIT

Synthesis (like any other protein synthesis): transcription/translation-preprohormone-prohormone-hormone-secretory granules/vesicles STORED IN CELLS

RELEASE STIMULI : Exocytosis

Transport : Hydrophilic, freely circulate in the blood vessel
No plasma protein binding
Short half-life; minutes

Question 13

2. Steroidal hormones

Chemical structure
Synthesis
Release
Transport

Answer 13

Chemical structure : cholesterol as the base
cortisol, aldosterone (adrenal cortex) & sex hormones (gonads)

Synthesis : like any steroidal synthesis
Enzymatic conversion of precursor (cholesterol base) molecules into hormone
Not stored in the cells

Release :
Stimulus increase precursor level and enzyme activation
Simple diffusion across membrane

Transport :
Lipophilic
Binds with Plasma protein
Half-life: hours to days

Question 14

Peptide hormones, why not bind to any plasma protein in order to increase its half life?

Answer 14

Mostly protein, not freely moving to bind

Question 15

Where does steroidal hormone bind to?

Answer 15

Binding/carrier plasma protein IN the blood vessel

Question 16

3. Tyrosine containing

Chemical structure
Synthesis
Release
Transport

Answer 16

Chemical structure : tyrosine as the base
thyroid hormones and catecholamines (adrenal medulla)

Synthesis : Thyroxine < Tyrosine > Epinephrine

Release : Stimulus required
Simple diffusion across membrane

Transport : Binds with Plasma protein (Weak and reversible bonds)
Half-life: hours to days

Question 17

4. Eicosndoids

Chemical structure
Synthesis
Release
Transport

Answer 17

Chemical structure : Polyunsaturated fatty acid derivatives
Eg; prostaglandins, leukotrienes, prostacyclins and thromboxanes

Synthesised by stereo- and regio-specific peroxidation of arachidonic acidby three enzyme families namely lipoxygenases, cyclooxygenases, and cytochrome P450

Release
Stimulus required
Poorly diffuse through cell membrane

Transport
Eicosanoids require transporter (anionic)
Half-life: in seconds: rapidly inactivated: Limited to autocrine and paracrine effects

Question 18

1. Peptide hormone FUNCTION

Answer 18

for example hormone binds to G-protein receptor [ACTH, glucagon] > signal transduction > physiological response

hormone [insulin, growth hormone] > receptor > tyrosine kinase > signal transduction > physiological response

Question 19

2. Steroidal hormonal FUNCTION (& thyroid hormones)

Answer 19

• Intracellular receptors & transcription factors

Glucocorticoid receptor - Cortisol
Mineralocortioid receptor - Aldorsterone
Androgen receptor - Testosterone

Question 20

Steroidal hormone step by step = specific proteins & biological effect

Answer 20

Hormone > diffusion> nuclear receptor (in nucleus) > DNA > mRNA > specific proteins & biological effects

Hormone > Cytosolic receptor > into nucleus > DNA > mRNA > specific proteins & biological effects

Question 21

Hormonal homeostasis:
feedback regulation types?

Answer 21

• OUTCOME (Y) of a PROCESS (X) acts to regulate the RATE of the PROCESS

Process (x) > [+] Outcome (y) < [-] Process (x) =
-ive feedback : OUTCOME -ively controls PROCESS (maintain a set-treshold)

Process (x) > [++] Outcome (y) < [+] Process (x) = +ive feedback : outcome amplifies the PROCESS

Question 22

Hormonal Homeostasis types;

Answer 22

(a) Simple Feedback Axis
(b) Hypothalamus-Pituitary- Axis
(c) Neuroendocrine reflux’s

Question 23

(a) Simple Feedback Axis

Answer 23

Endocrine Gland > Hormone > Target cells (glucose-induced insulin secretion

Question 24

(b) Hypothalamus-Pituitary- Axis

Answer 24

Higher centres tress > Hypothalamus > releasing hormone (CRH) > Anterior Pituitary > trophic hormone (ACTH) > target cells (bret tissue) / Peripheral Endocrine Gland > Hormone (cortisol) > Target cells (response)

Question 25

Endocrine / Hormonal Disorders

Answer 25

- Can be too much secretion - Could need a specific hormone in the circulation - Tumour

Question 26

Hormone released from peripheral gland we refer to them as a _________ _________

Answer 26

primary defect

Question 27

What's responsible for stress?

Answer 27

Cortisol If releasing less > e.g. tumour in adrenal gland > cortisol level goes low in blood > more ACTH Problem is with peripheral endocrine gland

Question 28

How can cortisol be tested?

Answer 28

In urine

Question 29

High amount of ACTH > effect on cortisol

Answer 29

Increased amount

Question 30

Primary defect

Answer 30

CRH ACTH

Question 31

Secondary defect

Answer 31

ACTH CORTISOL

Question 32

Exception = e.g. lung cancer [ectopic] = need _____

Answer 32

ACTH > acts on peripheral gland to release more cortisol

Question 33

Ectopic producing tumour =

Answer 33

Small cell lung tumour, pancreatic, ovarian

Question 34

1) Hyper-secretion 2) Hypo-secretion 3) dysfunction/impaired receptors

Answer 34

1) Hormone excess (hyper-secretion) - Tumour or immunological factor (Graves disease) 2) Lack of hormone (hypo-secretion) - Genetic, immunological attack, destruction by disease, surgical removal (Type 1 diabetes mellitus) 3) Decreased target-cell responsiveness - At level of receptor or downstream enzyme (Type 2 diabetes mellitus)

Question 35

Tumour in peripheral gland

Answer 35

Primary

Question 36

pituitary or ectopic

Answer 36

Secondary