Introduction To Endocrinology Flashcards Preview

Physiology > Introduction To Endocrinology > Flashcards

Flashcards in Introduction To Endocrinology Deck (41):

What is a paracrine hormone

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


What is neurotransmitter secretion

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


What is hormonal secretion

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


What is neurohormone secretion

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


What are some functions of the endocrine system

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


What are the complex factors of the endocrine system

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


How many hormones does the anterior pituitary produce



What cells produce somatostatin

D cells in the pancreas


Neurones of hypothalamus


What does vasopressin do roughly

Increase renal rubble permeability of water


Arteriolar vasoconstrictor


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

Menstrual cycle


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

Testosterone etc
Sperm production


What is a tropic nourishing hormone

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


What does a tropic hormone do

Stimulate and maintain their endocrine target tissue

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


What are some hydrophillic hormones

Hydrophillic - water loving low lipid sol


What are catecholamines

Derived form amino acid tyrosine
Prod in adrenal medulla


What are indoleamines

Derived form amino acid tyroptohan
Prod by pineal gland


What are some lipophilic hormones

Lipid loving poorly sol in water
Thyroid hormone
Sex hormones


What are thyroid hormones

Amines derived from tyrosine add iodine - iodinated tyrosine derivative


What are steroid hormones

Derived from cholesterol
Sex hormones


What does the solubility properties of a hormone determine

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)


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

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


What is a common precursor for steroid hormones



Are steroid hormones stored

No only the precursor cholesterol is


How are peptide hormones transported in the blood

As they are hydrophilic they are transported simpler diffused in blood


How are steroid hormones and thyroid hormone transported in the blood

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


What lipophilic hormone is bio active

Only freely dissolved unbound


Where are the hormonal receptors for hydrophilic and lipophilic hormones

Hydrophilic - sp receptors on the outer PM

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


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

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


What su the effective plasma concentration dependant on

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


How is the effective plasma concentration usually regulated

By changes in the rate of its secretion


Do endocrine glands secrete at a constant rate

No secretion varies and is subject to control


What are some general mechanisms controlling secretion

Negative feedback


Diurnal rhythm


What is an example of negative feedback

Control of free thyroid hormone circulating


What is an example of a neuroendocrine reflex

Increased sec of cortisol during stress


What is diurnal rhythm

Sleep/wake pattern
Cortisol greatest at morning and decreases throughout the day


What do endocrine disorders commonly arise form

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


What occasionally causes an endocrine function

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


What is hypo secretion

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


What is a treatmeant for hyposeceretion

Replacement therapy


What is hypersecrtion

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


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

The nervous system rapid very precise interaction with the external environment

The endocrine system require duration rather than speed