Endocrine Hormones - Peter Jones

Question 1

What is an endocrine associated molecule?

Answer 1

A hormone that is secreted from a non-nueronal cell into the blood

Question 2

What us a neuroendocrine cell?

Answer 2

A neuronal cell that releases hormone into the blood. An example is Growth Hormone Releasing Hormone. These hormones are made in the nerves.

Question 3

What is a neurotransmitter?

Answer 3

A neurotransmitter is a chemical released from a neuronal cell to act locally on another cell, like acetylcholine.

Question 4

What is a parocrine hormone?

Answer 4

A paracrine hormone is a hormone that acts on another cell, like glucagon.

Question 5

What is an autocrine hormone?

Answer 5

An autocrine hormone is a hormone that acts on the same cell, like insulin

Question 6

Give an example of a molecule that is both a neuroendocrine hormone and a neurotransmitter.

Answer 6

Dopamine- it is a neuroendocrine hormone if released into the bloodstream by a neuronal cell. It is a neurotransmitter if dopamine is released into a synaptic cleft and it binds to an effect or a cell

Question 7

Why do we need hormones?

Answer 7

Needed to enable communication between cells- they are essential

Question 8

Name five roles of hormones

Answer 8

1) Growth and differentiation of cells
2) Regulate energy storage, metabolic rate and temperature
3) Reproduction
4) Pregnancy and Lactation
5) Osmotic level and blood pressure

Question 9

Define a hormone

Answer 9

A hormone is a substance secreted by cells found in endocrine cells and endocrine glands. This includes neuronal and non neuronal cells.

Question 10

How do hormones work ?

Answer 10

Hormaones released into the bloodstream and transported to target tissue in the blood. They act on target tissue through specific receptors - different tissues have different receptors

Question 11

State and describe the 4 types of hormoes in the body

Answer 11

1) Steroid hormones - derived from Cholesterol. Pregnenolone is the precursor for all steroid hormones.
2) Derived from the amino acid (AA) - Tyrosine. Examples : Adrenaline, T3, T4, Melatonin.
3) Peptides - ADH and Oxytocin (<30 AA + 2D structure)
4) Polypeptides- larger than 3) and 3D structure. LH, FSH, Insulin, TSH

Question 12

Why do polypeptide hormones have sugar residues on them?

Answer 12

1) Increase half life

2) Increase specificity for receptor binding

Question 13

Give an example of 2 hormone from each of the four types

Answer 13

1) Steroid - Testosterone and Progesterone
2) Tyrosine based - Adrenaline and T3
3) Peptide based - Oxytocin and ADH
4) Polypeptide based - Insulin, FSH

Question 14

Name the cell that secretes (poly)peptide hormones

Answer 14

(Poly)peptide secreting endocrine cell

Question 15

How is a (poly)peptide endocrine cell suited for its role?

Answer 15

Has lots of RER to make proteins, Golgi to modify the protein

Question 16

Describe the steps to make a peptide hormone

Answer 16

Initial peptide made much bigger via RER (Prohormone). Prohormone sent to the golgi - modified by cutting prohormone to form hormone. Hormone in vesicles in intracellular fluid and stored until depolarisation via Ca2+ influx

Question 17

How is a steroid secreting cell suited for its role?

Answer 17

Has lots of lipid droplets containing cholesterol, several mitochondria and SER.

Question 18

Describe how steroid hormones are made

Answer 18

Cholesterol (c27) converted to Pregnenolone (C21). This is then transferred to SER where decarbonating occurs to produce the desired hormone

Question 19

Match the following numbers and letters and explain why this is the case:

1) Steroid hormone
2) Peptide hormone
a) Short half life
b) Long half life

Answer 19

1) Steroid hormone - b) Long half life - diffuses out of the cell quickly and binds to plasma poroteins
2) Peptide hormone - a) Short half life (no binding to plasma proteins - DOUBLE CHECK THIS)

Question 20

Name examples of organs that secrete peptide hormones

Answer 20

Pancreas, Anterior pituitary and parathyroid gland

Question 21

Name examples of organs that secrete steroid hormones

Answer 21

Adrenal cortex, testes and ovaries

Question 22

How to peptide hormones work?

Answer 22

Bind to receptors as they cannot cross the membrane, also why they are released by exocytosis. Bind to receptor on cell surface - conformational change translated across membrane to change the inner part of the receptor conformation. This changes enzyme activity and messenger levels.

Question 23

What are the different types of receptors?

Answer 23

1) Monomeric receptors- epidermal growth factor corsses plasma membrane
2) Multimeric receptors with membrane spanning and extraceullular subunits - Insulin binds to the alpha subunits- conformational change in beta units —> activates tyrosine kinase —> phosphorylates and changes activity of the cell
3) 7 transmembrane spanning receptors - beta receptors adrenergic AKA G- coupled receptors

Question 24

What is the MOA of steorid hormones?

Answer 24

Cross the cell membrane via diffusion. The hormone binds to a receptor and the hormone receptor complex binds to a specific DNA sequence. It can interact with other transcription factors and enhance synthesis of specific proteins,

Question 25

Describe negative feedback using Insulin as an example

Answer 25

1) An external Stimulus ( elevated plasma glucose levels)
2) Endocrine cell respons ( Beta cells increase insulin secretion)
3) Hormone in blood which are rapidly cleared by kidneys and liver (Plasma insulin conc increases)
4) Hormone binds to target cells - transports glucosefrom plasma to intracellular space
5) Response (plasma glucose back to normal)