Overview of Hormonal Secretion

Question 1

What type of secretion is hormonal?

Answer 1

Endocrine = into blood

Question 2

What are the X2 types of hormone delivery into the blood?

Explain each or these.

Answer 2

1) endocrine = hormone released from cell to blood

2) neuroendocrine = hormone released from nerve into blood

Question 3

Name some examples of neuroendocrine secretion.

Answer 3

1) hypothalamus
2) posterior pituitary
3) adrenal medulla

Question 4

Explain each of the following:

1) merocrine
2) apocrine
3) holocrine
4) endocrine
5) paracrine
6) autocrine

Answer 4

1) merocrine = hormone filled vesicles in cells fuse with cell membrane
2) apocrine = hormones create vesicles for release from cell membrane
3) holocrine = cell dies to release hormone
4) endocrine = hormone release into blood
5) paracrine = hormones released act locally
6) autocrine = hormone released acts on the same cell which released it

Question 5

What are the X3 main classes of hormones?

Answer 5

1) proteins/peptides
2) steroids
3) amines

Question 6

How do peptide/protein hormones circulate in the blood?

Answer 6

Unbound as they are polar

Question 7

Why is the rate of steroid hormone release slow?

Answer 7

It relies on the rate of production as they are not stores in the cells of the gland

Question 8

How do steroid hormones circulate on the blood?

Answer 8

Bound to albumin as they are all derived from fat soluble lipids

Question 9

What is the general structure of a steroid?

Answer 9

X3 six carbon ring structures

X1 five carbon ring structure

Question 10

What are amine hormones?

Answer 10

They are hormones derived from tyrosine

Question 11

Give examples of amine hormones.

Answer 11

Catecholamines

Thyroid hormones (T3 and T4)

Question 12

How are thyroid hormones stored?

Answer 12

In the thyroid bound to thyroglobulin

Question 13

How are thyroid hormones found in blood?

Answer 13

Circulating bound to proteins as they are lipid soluble

Question 14

How do the catecholamines circulate in blood?

Answer 14

Freely and unbound as they are are water soluble

Question 15

What fourth, smaller group of hormones do thromboxane and prostaglandins fall under?

Answer 15

Eicosanoids

Question 16

What generic precursor are ecosanoids synthesised from?

Answer 16

Arachidonic acid

Question 17

Which groups of hormones are linked to neurosecrectory cells?

Answer 17

Proteins and catecholamines

Question 18

Where will the receptor be found for protein and catecholamines hormones?

Why?

Answer 18

On the cell surface as these type of hormones are polar therefore can not cross lipid membranes

Question 19

Where will the receptor be found for steroid and thyroid hormones?

Why?

Answer 19

Intracellularly and these type of hormones are lipid-soluble (non-polar) therefore can cross the lipid membrane

Question 20

What is another name for the anterior pituitary?

Answer 20

Adenohypophosis

Question 21

What is another name for the posterior pituitary?

Answer 21

Neurohypophysis

Question 22

From what buffalo cavity outgrowth does the anterior pituitary form?

Answer 22

Rathke’s pouch

Question 23

From what does the posterior pituitary evaginate from to form?

Answer 23

The diencephalon (forebrain)

Question 24

How is posterior pituitary hormone release controlled?

Answer 24

Directly from neural projections from the hypothalamus

Question 25

Which X2 nuclei are involved in posterior pituitary control?

Answer 25

PVN = paraventricular nuclei

SON = supraorbital nuclei

Question 26

What connects the hypothalamus with the posterior pituitary gland?

Answer 26

A pituitary stalk called the infundibulum

Question 27

What hormones does the posterior pituitary secrete?

Answer 27

ADH and oxytocin

Question 28

In which hypothalamic nuclei is ADH synthesised?

Answer 28

PVN and SON

Question 29

In which hypothalamic nuclei is oxytocin synthesised?

Answer 29

PVN only

Question 30

What stimulates ADH release?

Answer 30

High plasma osmolarity, decreased blood volume and decreased blood pressure (in that order)

Question 31

What stimulates oxytocin release?

Answer 31

Cervix stretching

Question 32

How is anterior pituitary hormone release controlled?

Answer 32

The hypothalamus synthesises and secretes releasing factor hormones into the surrounding vessels which then triggers anterior pituitary synthesised hormones to be released.

Question 33

Through which network of vessels does the hypothalamus trigger anterior pituitary hormone releases?

Answer 33

The pituitary portal system

Question 34

Where do the nerve axons for releasing factor release into the pituitary portal system terminate?

Answer 34

At the median eminence at the base of the hypothalamus

Question 35

How many hormones does the anterior pituitary synthesise and release?

How many of these are trophic? Can you name these?

What does trophic mean?

Which hormone of the anterior pituitary is not trophic?

Answer 35

X6

X5

• thyroid stimulating hormone
• follicle stimulating hormone
• adrenocorticotrophic hormone
• leutinising hormone
• growth hormone

Tropic = stimulates other endocrine glands downstream

Prolactin = NOT trophic

Question 36

What are the X6 hypothalamic hypophysiptrophic hormones?

What doe each of these stimulate?

Answer 36

1) thyroid releasing hormone = TSH
2) dopamine = inhibits prolactin
3) corticotrophic releasing hormone = ACTH
4) gonadotropin releasing hormone = LH and FSH
5) growth hormone releasing hormone = GH
6) somatostatin = inhibits GH

Question 37

Why are hypothalamic hypophysiotrophic hormones difficult to measure?

Answer 37

They are only released in small amounts therefore are almost undetectable at a wider circulatory level