Flashcards in Endocrine Deck (30):
Describe the differences between the nervous system and the endocrine system.
1. Nervous system
-nerve impulses/ neurotramitters
-faster responses, briefer effects, Acts on specific target
2. Endocrine system
- hormone mediator molecule release in 1 part of body but regulates activity of cells in other parts
- slower responses, Effects last longer, broader influence
Describe the main function of endocrine glands, and how the function is carried out.
- secrete chemical substances called hormones
- they are ductless glands, they secrete hormones directly into blood vessels and not into ducts.
What is a hormone?
A hormone is a chemical messenger that influences or controls the activities of other tissues or organs.
Describe hormone activity
- hormones affect only specific target tissues with specific receptors on target cell me,brands
- receptors constantly synthesised and broken down- regulated by the cell (down and up regulation)
Name the two hormone types
1. Circulating- throughout the body
2. Local hormones- act locally eg paracrine ( neighbouring cells), autocrine ( act on same cell)
Name and describe the 2 classification of hormones
1. Lipid soluble
Steroid- adrenal cortex, sex
2. Water soluble
Amine- adrenaline, nor- adrenaline
Peptide/protein- hypothalamic, pituitary, pancreatic,parathyroid
How do steroid hormones enter the cell?
1. Diffuses through the plasma membrane and binds to an intracellular receptor
2. The Receptor hormone complex enters the nucleus
3. The receptor hormones complex binds a hormones response element
4. Binding initiates transcription of the gene to mRNA
5. The mRNA directs protein synthesis
How to water soluble hormone enter the cell?
Interact with receptor sites on the cells of the target tissues
What are the 4 mechanisms that control the secretion of hormones?
2. Hormonal stimulus
3. CNS control
Describe an example of Humoral stimulus
1. Capillary blood has low concentration of Ca+
2. Stimulates secretion of parathyroid hormone by the parathyroid gland
Describe an example of neural stimulus
1. Preganglionic sympathetic fingers stimulates adrenal medulla cells To secrete catecholamine (adrenaline/noradrenaline).
Describe an example of hormonal stimulus
1. Hypothalamus secretes hormones that
2. Stimulate the anterior pituitary gland that
3. Stimulate other endocrine glands to secrete hormones
What is biorhythms?
A rhythmic alteration in a hormone's rate of secretion. Eg, circadian rhythm- cortisol, hormones of menstrual cycle.
What does the hypothalamus secrete?
Releasing hormones and release-inhibiting hormones.
Name the 6 hormones of the anterior pituitary
1. Human growth hormone (hGH)
2. Thyroid stimulating hormone (TSH)
3. Follicle stimulating hormone (FSH)
4. Luteinizing hormone (LH)
5. Prolactin (PRL)
6. Adrenocorticotrophic hormone (ACTH)
What does human growth hormone act upon and its effects?
Stimulates secretion of insulin like growth factor, that promote growth (skeletal muscle and long bones), and protein synthesis( liver glycogen to glucose).
What does prolactin act on and what are it's effects?
Acts on the Mammary glands, promotes milk production in women.
What does thyroid stimulating hormone act upon,and what are its's effects?
- stimulates secretion of thyroid hormones T3 and T4
What does adrenocorticothrophic hormone act upon and what are it's effects?
- stimulates secretion of glucocorticoid steroids
What does Follicle stimulating hormone act upon, and what are it's effects?
-testes and ovaries
- stimulates the development of ova and sperm
What does lutenising hormone act upon and what are it's effects?
- testes and ovaries
-secretion of sex hormones in male and female, ovulation in female
What 2 hormones are secreted by the posterior pituitary gland?
1. Oxytocin (OT)
2. Anti diuretic hormone (ADH)
List the 8 major endocrine glands of the body
2. Pineal gland
3. Pituitary gland
4. Thyroid gland
5. Thymus gland
6. Adrenal glands
8. Gonads- testes and ovaries
What are the functionsof ADH?
1. Decreases urine production- causes the kidneys to return more water to blood
2. Decreases sweat production- water lost through sweating
3. Constriction of arterioles- which increases blood pressure
What is diabetes insipidus?
It is diabetes due to ADH deficiency, profound diuresis
What does oxytocin act upon and what are it's effects?
1. Uterus- stimulates contraction of muscles of uterus, plays a role in labour and delivery of baby.
2. Mammary glands- plays a role in breastfeeding, stimulates contraction of smooth muscle around mammary ducts.
What is the milk let down reflex?
The release of milk in response to suckling
What is the control of thyroid hormone secretion?
- thyrotropin releasing hormone is released from hypothalamus
- thyroid stimulating home released from anterior pituitary
-TSH acts of thyroid follows and increase production and release of T3, T4
What are the 8 actions of thyroid hormones?
1. Increase basal metabolic rate
2. Stimulate synthesis of ATP
3. Increase body temperature
4. Increase use of glucose and fatty acids for ATP production
5. Stimulate protein synthesis
6. Stimulate lipolysis
7. Enhance some actions of adrenaline
8. Regulate development and growth of nervous tissue and bones