Overview hormones

Question 1

define a hormone

Answer 1

substance created directly into the blood stream (ductless) from endocrine gland

Question 2

what gland secretes TSH and what does it do?

Answer 2

Thyroid-stimulating hormone released from ant. pituitary gland
Acts on thyroid gland (affects T4, T3)

Question 3

What are the 3 types of intercellular messengers in the body

Answer 3

endocrine
autocrine (secreted from and acts on same cell)
paracrine (neighbouring cell target)

Question 4

Explain the neuroendocrine messengers in the body

Answer 4

Stored in axon terminal. Hormones made are called neurohormones

Question 5

neuroendocrine messenger, give 2 examples neurohormones and where they come from

Answer 5

oxytocin and arginine vasopressin (antidiuretic)

come from posterior pituitary gland

Question 6

What are the 4 types of hormones? give example of each

Answer 6

Peptide hormone - TSH
Steroid hormone - cortisol
Derived from tyrosine - thyroid hormones
Eicosanoids - prostaglandins

Question 7

peptide hormone synthesis. Explain the process of synthesis of peptide hormone starting from DNA

Answer 7

DNA - mRNA - protein (in cytosol) = preprohormone
Ribosomes - cleaves pre = prohormone
Golgi complex - processed and packaged = hormone
exocytosis upon arrival of stimulus

Question 8

What’s a preprohormone?

What’s the pre- part?

Answer 8

precursor polypeptide

pre part means it is a signal peptide - saying it needs to be processed then secreted

Question 9

Steroid hormone synthesis. Explain the entire process

Answer 9

no DNA involved
cholesterol as the precursor molecule - enzymatic conversion = lipophilic hormone (now can’t be stored)
hormone leaves via passive diffusion

Question 10

What’s the starting point of steroid hormone synthesis?

Answer 10

cholesterol

Question 11

DNA not involved – T/F?

Answer 11

TRUE

Question 12

How does the hormone leave the cell? How does it move around the blood?

Answer 12

passive diffusion
isn’t dissolved in blood so can’t be moved easily
attached to a carrier protein to aid transport

Question 13

what dictates the rate of steroid hormone and peptide hormone synthesis?

Answer 13

steroid - by how much is released

peptide - rate of exocytosis

Question 14

between peptide and steroid hormones, which has the longer half-life and why?
What’s one special exception?

Answer 14

steroid and thyroid hormones have the longer half life and peptide hormones are prone to protein degradation
one special exception is if the hormone is bound?

Question 15

what are the 2 receptor types for peptide hormones? How do peptide hormones cause action on the target cell?

Answer 15

G-protein coupled receptors (cause action via glucagon activating cAMP)
Tyrosine kinase linked receptor (e.g. insulin) cause action by releasing tyrosine kinase in cell

Question 16

How do steroid hormones cause effect? What are the 2 receptor types?

Answer 16

binds to gene as a transcription factor to increase or decrease transcription of protein
cytosolic or nuclear receptor

Question 17

what 3 things can metabolise hormones?

How are they excreted?

Answer 17

enzymes in liver, kidney, blood

excreted in urine and/or faeces

Question 18

Explain negative and positive feedback

Answer 18

Negative feedback
– consequence negatively controls process (maintain a set-point)
Positive feedback
– consequence enhances or amplifies process further

Question 19

what’s an endocrine axis?

Answer 19

series of endocrine glands, where hormones affects the other glands in the series

Question 20

How can neuroendocrine reflexes influence hormone synthesis?

Answer 20

input from higher centres - can influence the endocrine

Question 21

what’s the diurnal pattern of hormone secretion and give an example

Answer 21

Levels of cortisol spike as you wake. During the course of day, cortisol is used up. Trials and tribulations of waking day require cortisol
As you go on, in evening, a little more is produced to get through the day. In the night, you make more to ‘prep it in advance’ for the next day
Important for sampling blood for hormone patterns
summary - cortisol - peak in early morning, trough in late evening

Question 22

what are the 3 types of hormone disorders?

Answer 22

1. hormone excess (tumour or immunological = Graves’ disease)
2. lack of hormone (genetic, immunological attack, surgical removal)
3. decrease target-cell responsiveness

Question 23

Distinguish between a primary and secondary defect

Answer 23

primary - associated with endocrine gland that makes the hormone
secondary - associated with anterior pituitary level at endocrine axis

Question 24

how would you test for hyper and hyposecretion?

Answer 24

hyper- suppression test (failure to suppress indicates autonomous secretion)
hypo - stimulation test (failure to stimulate confirms)

Question 25

what role does imaging play in diagnosing endocrine disorders?

Answer 25

many endocrine disorders are due to a presence of a tumour