Introduction To Endocrinology

Question 1

What is a paracrine hormone

Answer 1

Local chemical messenger distributed via simple diffusion not blood stream
Travel short distances only
Example histamine

Question 2

What is neurotransmitter secretion

Answer 2

From nerve terminals rely on diffusion in response to electrical signal before act on target which is usually another neurone via synaptic cleft

Question 3

What is hormonal secretion

Answer 3

Long range sec from gland into blood to the target cell need specific receptor in order to illicit a cellular response

Question 4

What is neurohormone secretion

Answer 4

ADH syn in nerve cells and released from terminal in response to action potential with release of ADH in blood to target tissue

Question 5

What are some functions of the endocrine system

Answer 5

Regulating the metabolism, water and electrolyte balance
Regulate nutrient supply insulin glucagon
Inducing adaptive changes to help the body cope with stressful situations adrenaline and cortisol
Promoting smooth and sequential growth and development form action of growth hormone
Controlling sexual differentiation and reproduction
Regulating RBC production
Controlling and integrating activities of both the circulatory and digestive systems

Question 6

What are the complex factors of the endocrine system

Answer 6

A single endocrine gland may produce multiple hormones

A single hormone may be secreted form more than one gland

A single hormone has more than one type of target cell and therefore can induce more than one type of effect

Rate of secretion of some hormones can vary over time in cyclic pattern

A single target cell can be influenced by more than one type of hormone

The same chemical messenger may be either a hormone or neurotransmitter

Some organs are exclusively endocrine in function whereas some organs exhibit non endocrine functions also

Question 7

How many hormones does the anterior pituitary produce

Answer 7

6

Question 8

What cells produce somatostatin

Answer 8

D cells in the pancreas

Also

Neurones of hypothalamus

Question 9

What does vasopressin do roughly

Answer 9

Increase renal rubble permeability of water

Also

Arteriolar vasoconstrictor

Question 10

What is an example of the rate of secretion of some hormones can vary over time in cyclic pattern

Answer 10

Menstrual cycle

Question 11

Give an example of an endocrine organ which has non endocrine qualities also

Answer 11

Testes
Testosterone etc
Sperm production

Question 12

What is a tropic nourishing hormone

Answer 12

A hormone which has its primary function to regulate the secretion of another hormone form a different endocrine gland

Question 13

What does a tropic hormone do

Answer 13

Stimulate and maintain their endocrine target tissue
Eg

TSH
Into blood to thyroid gland to release thyroid hormones but receptors on the gland which maintain tissue if TSH absent gland should shrink

Question 14

What are some hydrophillic hormones

Answer 14

Hydrophillic - water loving low lipid sol
Catecholamines
Indoleamines

Question 15

What are catecholamines

Answer 15

Derived form amino acid tyrosine
Adrenaline
Prod in adrenal medulla

Question 16

What are indoleamines

Answer 16

Derived form amino acid tyroptohan
Melatonin
Prod by pineal gland

Question 17

What are some lipophilic hormones

Answer 17

Lipid loving poorly sol in water
Thyroid hormone
Sex hormones

Question 18

What are thyroid hormones

Answer 18

Amines derived from tyrosine add iodine - iodinated tyrosine derivative

Question 19

What are steroid hormones

Answer 19

Derived from cholesterol
Sex hormones
Aldosterone

Question 20

What does the solubility properties of a hormone determine

Answer 20

1) how hormone is processed (syn and sec) by the endocrine cell
2) how hormone is transported in blood (hydrophillic vs lipophilic)
3) how hormone exerts its effects at the target cell (hydrophilic can’t diffuse across PM where as lipophilic can)

Question 21

What is the processing of hydrophilic peptide hormones (long answer)

Answer 21

1) large inactive precursor protein (preprohormone) are syn by ribosomes on RER
2) they then migrate to the golgi complex in transport vesicles form smooth ER
3) enzymes in the ER cleave the preprohormone to active hormones
4) the golgi complex packages the finished hormones into secretory vesicles that pinch off and store in the cytoplasm til a signal triggers for secretion
5) on stimulation the secretory vesciles fuse with PM and release contents by exocytosis

Question 22

What is a common precursor for steroid hormones

Answer 22

Cholesterol

Question 23

Are steroid hormones stored

Answer 23

No only the precursor cholesterol is

Question 24

How are peptide hormones transported in the blood

Answer 24

As they are hydrophilic they are transported simpler diffused in blood

Question 25

How are steroid hormones and thyroid hormone transported in the blood

Answer 25

Reversible bind to plasma proteins

Some plasma proteins are specific while others may carry more than 1 hormone - albumin

Question 26

What lipophilic hormone is bio active

Answer 26

Only freely dissolved unbound

Question 27

Where are the hormonal receptors for hydrophilic and lipophilic hormones

Answer 27

Hydrophilic - sp receptors on the outer PM

Lipophilic - bind with specific receptors located inside the target cell nucleus maybe

Question 28

What are the two ways a hormone can alter the cells protein

Answer 28

1) surface Binding hydrophilic hormones function largely by activating 2nd messenger pathways within the cell by using a preexisting intracellular protein
2) lipophilic hormones function mainly by activating specific genes in the target cell to cause formation of new intracellular proteins enzymatic or structural

Question 29

What su the effective plasma concentration dependant on

Answer 29

Hormones rate of secretion into the blood by the endocrine gland

For a few hormones its rate of metabolic activation or conversion

For lipophilic hormones its extent of binding to plasma proteins

It’s rate of removal form the blood by metabolic inactivation and excretion of urine

Question 30

How is the effective plasma concentration usually regulated

Answer 30

By changes in the rate of its secretion

Question 31

Do endocrine glands secrete at a constant rate

Answer 31

No secretion varies and is subject to control

Question 32

What are some general mechanisms controlling secretion

Answer 32

Negative feedback

Neuroendocrine

Diurnal rhythm

Question 33

What is an example of negative feedback

Answer 33

Control of free thyroid hormone circulating

Question 34

What is an example of a neuroendocrine reflex

Answer 34

Increased sec of cortisol during stress

Question 35

What is diurnal rhythm

Answer 35

Sleep/wake pattern

Cortisol greatest at morning and decreases throughout the day

Question 36

What do endocrine disorders commonly arise form

Answer 36

Abnormal plasma concentrations of a hormone caused by inappropriate rates of secretion - too little/much

Question 37

What occasionally causes an endocrine function

Answer 37

The sensitively of the target even if cooks Aconcagua of the hormone is normal

Question 38

What is hypo secretion

Answer 38

Primary - abnormality in gland - factors such as disease, dietary, chemical, toxic, idiopathic ( spontaneous disease) , iatrogenic (disease form medical examination)

Secondary - endocrine gland is normal but is secreting too little as an issue with tropic enzyme

Question 39

What is a treatmeant for hyposeceretion

Answer 39

Replacement therapy

Question 40

What is hypersecrtion

Answer 40

Primary - defect in gland
Secondary - excessive stimulation form outside

Causes - tumour, immunological facctors( antibody mimic)

Treatment - removal of tumour or drugs to block Acton of hormone

Question 41

What are the two body systems that have evolved which overlap and integrate at many levels

Answer 41

The nervous system rapid very precise interaction with the external environment

The endocrine system require duration rather than speed