Endocrine system

Question 1

Definition of
Hormones, endocrine gland, target cell

Answer 1

Hormone: regulatory substance produced by glands transported through blood

endocrine gland: produce hormone, does not have ducts (exocrine have (sweat, saliva, acid in digesting)

target cell: cells with receptor specific for a hormone

Question 2

where are Aminohormones derived and secreted from

Answer 2

all derived from Tyrosin

secreted from Thyroid gland, adrenal medulla, hypothalamus

Question 3

name the thyroid hormones

Answer 3

Thyroxine T4 (4 Iodines)
Triiodothyronine T3 (3 Iodines)

Question 4

name catecholamines

Answer 4

Epinephrine

Norepinephrine (NT can become hormone in blood secreted adrena medulla)

Dopamine (NT can become hormones in blood secreted by hypothalamus)

Question 5

pathway of secretory peptide hormone

Answer 5

signal -> translated in the rough ER -> Golgi and packed in vesicles and released out of cell

during synthesis and packaging: pre-pro-insulin -> pro-insulin -> insulin

Question 6

name Steroid hormones (lipids)

Answer 6

Cortisol, aldosterone - adrenal cortex
Testosterone - testis
Estradiol - secreted from ovaries

Question 7

Adrenocorticosteroids

Answer 7

steroids derived from Cholesterol secreted from adrenal cortex

DHEA(Dehydroepiandrosterone), Cortisol, Aldosterone, Androstenedione

Question 8

which hormones can’t cross the membrane

Answer 8

(Aminohormones) catecholamines with OH group - hydrophilic cant cross membrane -> bound to plasma protein

(Aminohormones) thyroid hormones - lipophilic (2 rings)

peptide hormones: hydrophilic - bound to plasma proteins

Steroids: lipophilic

Question 9

How can hydrophilic hormones act

Answer 9

they bind to a receptor on the surface and act as the first messenger - activating a signal in the cell (second messenger)

Question 10

What may happen to a hormone before it can act as a hormone

Answer 10

it is present in a pro form and gets activated by metabolism, f.e. Vitamin D

Question 11

Acting of lipophilic hormones

Answer 11

they can pass the membrane and bind directly to their target in the cell, but in the blood, they are bound on carrier protein (carrier stays outside of the cell)

Question 12

How to measure hormone concentration (very low concentration)

Answer 12

Bioassay, radioimmunoassay (radioactively labeled antibodies), ELISA (EPT - pregnancy or COVID19)

Question 13

How can the hormone response change?

Answer 13

Upregulation of receptors: Homoesatis -> can be caused by prolonged low concentration of hormones
Downregulation of receptors: the prolonged high concentration of hormones

permissive effects: Hormone A has to be present for the full effect of hormone B: f.e. Epinephrine works more efficient when thyroid hormone is present

Question 14

3 ways to control hormone secretion

Answer 14

ions and nutrients
Neurotransmitter
hormones

Question 15

Example of controlling hormones by ion or nutrients

Answer 15

Glucose goes up –> Insulin (hormone) increases –> Insulin causing uptake of Glucose –> Glucose goes down and Insulin goes down (neg. feedback, homoestatic)

Question 16

Example of controlling hormones by neurons

Answer 16

Autonomous nerve system
neurons releasing NT to adrenal medulla -> Epinephrine
releasing NT to Ganglion-> gland cell -> Insulin, GI hormones

Hypothalamus to anterior/posterior pituitary

Question 17

Hormones controlling hormones

Answer 17

Tropic hormones: hormones that stimulates release of another hormone (target is an endocrine gland cell)

Trophic(=feed) hormones: increase growth of a gland or tissue

some hormones can have both effects

Question 18

Endocrine disorder: Hyposecretion

Answer 18

too little secretion

Primary: problem with gland or production of hormone
secondary: too few tropic hormones

Question 19

Endocrine disorder: Hypersecretion

Answer 19

too much secretion

Primary: problem with gland or production of hormone
secondary: too many tropic hormones

Question 20

Hypo and Hyperresponsiveness

Answer 20

(too little/much) problem with the number or sensitivity of receptors on target cells
f.e.: sensitivity to Insulin

Question 21

The pituitary consists of…

Answer 21

Anterior lobe: Adenohypophysis

Posterior lobe: Neurohypophysis (extension of neural tissue)

both connected to the hypothalamus through the pituitary stalk

Question 22

Pathway of signal: anterior pituitary

Answer 22

hypothalamus -> releasing and inhibiting hormones are sent by nuclei to the hypophysial portal system -> anterior pituitary -> anterior pit. release their hormones -> bloodstream to the body

Question 23

Pathway of signal: the posterior pituitary

Answer 23

Supraoptic nuclei sends hormones through axons direct to posterior pituitary -> release of hormones into bloodstream to the body