Endocrine: Scope of Hormones

Question 1

Name the two body systems of control and communication which overlap and integrate at many levels

Answer 1

• The nervous system
• The endocrine system

Question 2

Define Hormone:

Answer 2

A chemical mediator that is secreted by an endocrine tissue or gland into the blood, which transports it to its target cells

Question 3

Define Endocrinology

Answer 3

The study of the homeostatic chemical adjustments and other activities that hormones accomplish

Question 4

Name the four types of intracellular communication mediated via extracellular chemical messengers:

-

-

-

-

Answer 4

• Paracrine secretion
• Hormone secretion
• Neurotransmitter secretion
• Neurohormone secretion

Question 5

What type of secretion is this?

Answer 5

Question 6

What type of secretion is this?

Answer 6

Question 7

What type of secretion is this?

Answer 7

Question 8

What type of secretion is this?

Answer 8

Question 9

Name some regulatory effects hormones exert throughout the body:

-

-

-

-

-

-

-

Answer 9

• regulating metabolism, water and electrolyte balance
• regulation of nutrient supply
• inducing adaptive changes to help the body cope with stressful situations
• promoting smooth, sequential growth and development
• controlling sexual differentiation and reproduction
• regulating red blood cell production
• controlling and integrating activities of both the circulatory and digestive systems

Question 10

What class of hormones are hydrophilic:

-

-

-

Lipophilic:

-

-

Answer 10

Hydrophilic:

• Peptide
• Catchecolamines
• Indoleamines

Lipophilic:

• Thyroid hormones
• Steroid hormones

Question 11

What does solubility properties of a hormone determine:

-

-

-

Answer 11

• How the hormone is processed by the endocrine cell
• How the hormone is transported in the blood
• How the hormone exerts its effects at the target cells

Question 12

Location of hydrophilic peptides and catecholamines:

-

-

Lipophilic steroids and thyroid hormone:

-

Answer 12

Hydrophilic peptides and catecholamines:

• poorly soluble in lipid
• bind to specific receptors on the outer PM surface of the target cell

Lipophilic steroids and thyroid hormone:

• bind with specific receptors located inside the target cell

Question 13

General means of hormone action

How do surface binding hydrophilic hormones function?

How do lipophilic hormones function?

Answer 13

Surface binding hydrophilic hormones function largely by activating 2nd messenger pathways within a target cell

Lipophilic hormones function mainly by activating specific genes in the target cell to cause formation of new intracellular proteins

Question 14

The effective plasma concentration of free, biologically active hormones can depend upon:

-

-

-

-

Answer 14

• Hormones rate of secretion into the blood by the endocrine gland
• For some hormones, its rate of metabolic activation or conversion
• For lipophilic hormones, its extent of binding to plasma proteins
• Its rate of removal from the blood by metabolic inactivation and excretion in the urine

Question 15

General mechanisms controlling secretion include:

-

-

-

Answer 15

• Negative feedback control
• Neuroendocrine reflexes
• Diurnal rhythms

Question 16

Endocrine disorders

Most commonly result from: ____________________________

-

-

Occassionally, endocrine dysfunction arises because:

Answer 16

Most commonly result from abnormal plasma concentrations of a hormone caused by inappropriate rates of secretion:

• Too little hormone secreted - hyposecretion
• Too much hormone secreted - hypersecretion

Occasionally endocrine dysfunction arises because target cell responsiveness to the hormone is abnormally low (even though plasma concentration of the hormone is normal)

Question 17

Hyposecretion

Primary:

Factors that can cause primary hyposecretion:

Secondary:

Treatment:

Answer 17

Primary: abnormality within the gland

Factors causing this include genetic, dietary, chemical or toxic immunological, disease, iatrogenic, idiopathic

Secondary: endocrine gland is normal but is secreting too little hormone because of a deficiency of its tropic hormone

Treatment: typically hormone replacement therapy

Question 18

Hypersecretion

Primary:

Secondary:

Causes:

-

-

Treatment:

-

-

Answer 18

Primary: defect lies in gland itself

Secondary: excessive stimulation from outside

Causes:

• Tumours - continuously secrete excess hormone
• Immunological factors - abnormal antibody mimics TSH

Treatment

• Removal of tumour
• Drugs - block hormone synthesis or inhibit secretion/action of hormone