Lecture 6: Hormones Flashcards
What are Hormones?
They enable communication between cells
What do Hormones do?
They are carried in the blood stream to specific target regions (other endocrine glands, organs, cells, the brain)
What are Exocrine Glands?
They secrete products to outside of the body through ducts (Sweat, tears)
What do Hormones regulate?
Growth and Development
Reproduction
Metabolism
Maintenance of internal environment - temp, sleep
Control of internal organs and systems - hr, bp
How is Hormone release regulated?
Through the process of Negative Feedback. Output from a gland (hormone) responsible for preventing further release.
What does the Pineal Gland Release?
Melatonin
What is Entrainment?
Matching of a physiological event to an environmental oscillation.
What are the steps of Melatonin production?
Pineal Gloand produces melatonin in the evening. Melatonin levels peak in middle of night.
Melatonin levels decline to low day time amounts.
Where is the Hypothalamus located?
Base of brain
What is the role of the Hypothalamic Nuclei?
They synthesise Hypothalamic Releasing Hormones which either stimulate or inhibit hormone release from pituitary gland.
What is the Pituitary Gland?
The Master Gland. It releases Tropic Hormones - hormones which influence the release of hormones from other glands.
What is the Anterior Pituitary?
Controlled by Hypothamalic Releasing Hormones
What is the Posterior Pituitary?
Controlled by nerve stimulation from hypothalamus.
(PPG) What is the Anti-diuretic Hormone? (ADH/Vasopressin)
Stimulates re-absorption of water by kidneys (conserves water as prevents it being lost in urine). Stimulates vasoconstriction (high bp in response to stress)
(PPG) What is Oxytocin?
Causes muscle contraction in uterus (handy in childbirth)
Stimulates ejection of breast milk (handy but not always)
(PPG) What is the Oxytocin - Tend or Befriend Hormone?
Elevated levels during sexual arousal and orgasm. Levels respond to social simulations causing anti-stress effects (inhibiting stress hormones)
(APG) What is the Growth Hormone?
Pre-pubertal deficits - Pituitary Dwarfism
Pre-pubertal excess - Gigantism
(APG) What is the Thyroid Stimulating Hormone?
Stimulates the release of Thyroxine by thyroid gland. If thyroid gland is unable to produce enough thyroxine, it swells up in attempt to meet deficit. This is called a Goiter
(APG) What are Gonadotrophins?
Sex hormone release
(APG) What is the Luteinzing Hormone?
It increases production of Progesterone (ovaries) and Testosterone (testes and adrenal cortex)
What is the Follicle Stimulating Hormone?
Increases production of Estrogen (ovaries) and Sperm (testes)
(APG) What is the Andrenocorticotropic Hormone? (ACTH)
Stress Hormone release. Stimulates release of stress hormones from adrenal cortex.
(APG) What is Prolactin?
Promotes tissue development in breasts during pregnancy. Stimulates milk production after birth.
What are the results of the Masturbation to orgasm in males study by Exton?
Control group - nothing happened
Adrenaline and Nor-adrenaline increase - responsible for increasing hr and bp.
Whilst watching porn these things start to increase and when reach orgasm they hit their peak. Same happens in females.
How long does Prolactin remain elevated for after orgasm?
60 minutes or more.
What causes greater Prolactin release?
Sex causes more prolactin release than masturbation in both males and females.
Who does Prolactin have a more profound effect on?
Males
What happens when there is sustained elevation of prolactin after orgasm?
Increases sexual satiety/reduces sexual desire. Decreases likelihood of subsequent erections and orgasms.
What is the evidence from Multi-orgasmic men?
Produce significantly less prolactin at orgasm so no reduction in desire - ability for more orgasms
What is the evidence from Impotence Treatments?
Decreases prolactin in release (Prolactin Antagonist). Increases sexual desire and decrease refractory period.
Where is the Adrenal Gland?
Sits on top of the kidneys
What are the 2 areas the adrenal gland is made up of?
Medulla (Inside) and Cortex (outside)
What is the Adrenal Medulla?
Responds to nerve impulses from hypothalamus
What is the Adrenal Cortex?
Responds to ACTH (from the pituitary gland)
What hormones does the Adrenal Medulla secrete?
Adrenaline and Nor-adrenaline
What does the Adrenal Medulla do?
Increases Hr, constricts peripheral blood vessels and glucose release. There is increased blood flow and energy supply to essential areas (muscles) and short term preparation for stress. Fight or flight hormone
What 3 types of hormones does the Adrenal Cortex secrete?
- Sex hormones (androgens and oestrogens)
- Mineralocorticoids (Aldosterone)
- Corticosteroids (Stress hormones - cortisol)
What do Mineralocorticoids do?
Help kidneys retain sodium and excrete potassium. Maintains BP and balance of salt and water in the body.
What do Corticosteroids do?
Maintains essential responses during stressful events
What hormones do the pancreas secrete?
Insulin and glucagon
What does the Pancreas do?
Maintains blood sugar levels. Picks up whether blood sugars are too high or too low.
What does the Pancreas do if blood sugars are too low?
Release glucagon which stimulates liver to release glucose into blood
What does the Pancreas do if blood sugars are too high?
Insulin is released. It mops up excess glucose and is taken up by fat cells.
What hormone does the testes secrete?
Male sex hormones (androgens)
Where else are Male sex hormones secreted from?
The adrenal cortex
What is the main Androgen?
Testosterone
When does production of Testosterone begin?
Begins during foetal development and there is a burst at puberty which stimulates males secondary characteristics
What hormone does the ovaries secrete?
Female sex hormone (Estrogens)
Where else are female sex hormones secreted from?
The adrenal cortex
What is Estradiol?
Breast development. Distribution of fat (hips, legs, breasts) and maturation of uterus and vagina
What is Progesterone?
Thickens lining of uterus in pregnancy
What do Progesterone and Estradiol do together?
Stimulates changes in uterus during menstrual cycle
