The Endocrine System

Question 1

What does the endocrine system regulate?

Answer 1

Development and aging
Growth
Reproduction
Metabolism
Blood pressure
Behaviour
Concentration of ions in the blood
Lactation

Question 2

Describe endocrine signalling

Answer 2

Hormones are secreted from endocrine cells into the bloodstream.

Question 3

Where are endocrine cells found?

Answer 3

Found in endocrine tissues or glands

Question 4

Basic principles of endocrine signalling

Answer 4

-enables signalling across long distances
-slow signalling
-signalling is specific to receptors

Question 5

Name the 3 types of hormones

Answer 5

Protein (insulin)
Amino acid derived (adrenaline)
Steroid (estradoil)

The hormone type can influence the cell membrane permeability

Question 6

What are the 7 endocrine glands?

Answer 6

Hypothalamus
Pituitary glands (anterior and posterior)
Thyroid
Parathyroid
Adrenals
Ovaries
Tested
Endocrine pancreas

Question 7

Briefly summarise the thyroid gland

Answer 7

The thyroid gland releases T3 and T4 hormones.
These hormones are amino acid derived hormones
The synthesis of these hormones depends on iodine.
If iodine is too low the thyroid hormones cannot be made which causes low metabolism
These hormones are transported across cell membranes using facilitated diffusion

Question 8

Briefly summarise the parathyroid gland

Answer 8

Parathyroid gland releases PTH
PTH is a protein hormone
It regulates plasma calcium and plasma phosphate
This hormone targets the bones, intestines and kidneys

Question 9

What is the role of ADH

Answer 9

ADH is a hormone that regulates water balance within the body. It prevents water loss

Question 10

What’s Adenohypophysis?

Answer 10

Anterior lobe of the pituitary gland
Develops from an upward projection of the pharynx

Question 11

What are Endocrine Glands and Endocrine Tissues?

Answer 11

Endocrine glands: structures that are specifically designed for the endocrine function

Endocrine Tissues: they tend to have endocrine cells in them but they perform other functions too

Question 12

What’s the difference between all 3 types of hormones?

Answer 12

Hormone type influences its cell membrane permeability - dictating (controlling) properties e.g. time of synthesis, release, receptor location.

Question 13

What’s the main difference about the synthesis of peptide hormones and steroidal/amino acid derived hormones?

Answer 13

Amino acid derived and steroidal hormones both require specific enzymes to be synthesised. while peptide hormones don’t.

THEREFORE, peptide hormones can be synthesised in any cell that has the gene for that hormone switched on. BUT amino acid derived or steroidal hormones can’t because they have to have the specific enzymes present as well.

Question 14

What is Neurohypophysis and its function?
*It is the posterior lobe of the pituitary gland

Answer 14

Develops from a downward projection of the brain

FUNCTION: Releases hormones from the large diameter neurons directly into systemic circulation

Question 15

What does Adenohypophysis and its function?
*It is the Anterior lobe of pituitary

Answer 15

Develops from an upward projection of the pharynx

FUNCTION: Troph cells stimulated by releasing hormones carried in the hypophyseal portal system from hypothalamic neurons

Question 16

What are the endocrine tissues?

Answer 16

Hypothalamus
Kidney
GI tract
Heart
Liver
Adipose tissue

Question 17

What do thyroid hormones do?

Answer 17

They bind to nuclear receptors - regulate transcription

They regulate:
Metabolism - basal metabolic rate
Development and growth

Question 18

Why don’t endocrine glands have ducts?

Answer 18

Because they secrete hormones directly into the bloodstream.

(ducts are basically tubes e.g. esophagus, intestines, trachea etc.)

Question 19

what does parathyroid hormone (PTH) regulate? and which parts does it target?

Answer 19

Regulates:
plasma calcium
plasma phosphate

Targets:
Bone
intestine
kidneys

Question 20

What does the adrenal cortex do?

Answer 20

Releases steroid hormones
Glucocorticoid e.g. cortisol
Mineralocorticoid e.g. aldosterone

Question 21

what does the adrenal medulla release?

Answer 21

Chromaffin cells release adrenaline
releases catecholamines - adrenaline, noradrenaline
via exocytosis in vesicles

Question 22

What does the pancreas gland consist of?

Answer 22

Islets of Langerhans (ADBI)
Beta cells - release Insulin
Alpha cells - produce Glucagon
both release into portal blood infulence the liver

Question 23

Explain how negative feedback is used to maintain homeostasis of a plasma calcium

Answer 23

Plasma [Ca2+] sensed by Chief cells
+ plasma [Ca2+]
–PTH release
–kidney tubule reabsorption
–bone Ca2+ resorption
–intestinal Ca2+absorption
Results in lowering plasma [Ca2+]

– = decreased

Question 24

Explain the negative feedback loop used to maintain blood glucose levels

Answer 24

+ blood glucose
Stimulates beta cells of islets of Langerhans
Which then release insulin
Liver decreases glucose synthesis
AND
Muscle increases glucose storage
Leading to decreased blood glucose levels

Question 25

What gland can switch from a negative feedback loop to a positive feedback loop?

Answer 25

The ovaries (which produce oestrogen and progesterone)

Question 26

What hormones do the testes produce?

Answer 26

Leydig cells in testes produce testosterone
-Stimulates protein synthesis
-Can lead to development and growth