W10 - The Endocrine System - Textbook Flashcards
What is the function of the endocrine system?
Regulates bodily functions to stabilise the body’s internal env.
What type of organ is the hypothalamus?
Neuroendocrine organ
What does the endocrine system consist of?
Host organ (gland)
Chemical messengers (hormones)
Target/receptor organ
Do endocrine glands have ducts?
NO
- Referred to as ductless glands.
What do endocrine glands do?
Secrete substances directly into extracellular spaces around the gland.
Do exocrine glands have secretory ducts?
YES
What do exocrine glands do?
Carry substances directly to a specific compartment or surface.
What controls almost all exocrine glands?
Nervous system
What are the 2 categories into which hormones generally fit into?
Steroid-derived hormones
Amine and polypeptide hormones synthesised from aa.
Difference in Steroid-derived hormones and Amine and polypeptide hormones synthesised from aa.
Amine and polypeptide hormones synthesised from aa are soluble in blood plasma.
What gives a good indication of how long a hormones effect persists?
Its half life
What are the 4 ways in which hormones alter cellular reactions of specific “target cells”?
- Modify rate of intracellular protein syn. by stimulation of nuclear DNA.
- Change rate of enzyme activity
- Alter plasma membrane transport via 2nd messenger system.
- Induce secretory activity
What does a target cells response to a hormone depend on?
Presence of specific protein receptors that bing the hormone in a complimentary way.
Where do target cell receptors occur?
Either on plasma membrane or in cells interior switch.
To which hormone do all cells contain receptors for?
Thyroxine
What does hormone-receptor binding represent?
1st step in starting hormone action.
What factors does the extent of a target cells activation by a hormone depend on?
Hormone conc in blood
No. of target cell receptors for hormone
Sensitivity or strength of the union between hormone + receptor.
What does the term up-regulation describe?
State when target cells form more receptors in response to ⬆️ hormone levels to ⬆️ the hormones effect.
What can prolonged exposure to high hormone concentrations do?
Can desensitise target cells to blunt hormonal stimulation.
What does the term down-regulation describe?
A loss of receptors to prevent target cells from over responding to chronically high hormone levels to ⬇️ the hormones effect.
What does the binding of a hormone w/ its specific receptor in the plasma membrane do?
Alters the target cells permeability to a chemical
= i.e insulins effect on cellular glucose uptake.
OR
Modifies the target cells ability to manufacture intracellular substances, primarily proteins.
In what 3 ways can a hormone increase enzyme activity?
Stimulating its production
Combining w. the enzyme to alter its shape = ability to act = ALLOSTERIC MODULATION
Activates inactive enzyme forms to ⬆️ the total amount of active enzyme.
What factors determine plasma concentration of a particular hormone?
Quantity synthesised in host gland
Rate of catabolism or secretion into blood
Quantity of transport proteins present
Plasma vol changes
What are the 3 types of endocrine gland stimulation?
Hormonal stimulation
Humoral stimulation
Neural stimulation
What is meant by humoral stimulation?
When hormone release is stimulated by changing levels of ions + nutrients in body fluids.
What is meant by a diurnal pattern of secretion?
Release of hormones at regular intervals during a 24hr/weekly cycle.
What is the anterior pituitary gland often called?
Master gland
What does the hypothalamus control?
Anterior pituitary activity.
What are the 3 ways in adults in which the growth hormone facilitates protein synthesis?
⬆️ aa transport through plasma membrane
Stimulating RNA formation
Activating cellular ribosomes that ⬆️ protein synthesis
As well as facilitating protein synthesis, what else does the growth hormone (GH) do?
Slows CHO breakdown
Initiates subsequent mobilisation + use of FAT as an energy source.
Prolactin (PRL) initiates + supports milk secretion from the mammary glands.
With what kind of activity do its levels increase and how quickly do they return to baseline?
⬆️ at high intensity
Return to baseline w/in 45mins of recovery.
What might repeated exercise-induced PRL release do?
May:
Inhibit function of the ovaries.
Contribute to menstrual cycle alterations when training intensely.
When can greater ⬆️ in Prolactin (PRL) release occur in women?
Those who run w.out undergarment support
Those who fast or consume a high fat diet.
Function of the gonadotropic hormones
Stimulate M + F sex organs to grow + secrete their hormones at a faster rate.
What are the 2 gonadotropic hormones?
FSH
LH
Function of FSH
Initiates follicle growth in ovaries
Stimulates ovaries to secrete oestrogen
Function of LH
Complements FSH in causing oestrogen secretion
Causes rupture of follicle = allowing ovum to pass through Fallopian tube for fertilisation.
What does FSH do in Males?
Stimulates germinal epithelium growth in testes to promote sperm development.
What does LH do in Males?
Stimulates testes to secrete testosterone.
Function of thyroid hormones
Provide essential stimulation for normal growth + development, especially of nervous tissue.
When can the actions of thyroid hormones becomes most noticeable?
In those who suffer from hyper secretion or hypo secretion.
What is the term for hyper secretion of thyroid hormones
Hyperthyroidism
What 4 effects are there to hyperthyroidism
⬆️ O2 consumption + metabolic heat prod at rest.
⬆️ protein catabolism = muscle weakness = weight loss
Heightened reflex activity + psych disturbances i.e insomnia
Tachycardia
What is the term for hypo secretion of thyroid hormones
Hypothyroidism
What 4 effects are there to hypothyroidism
⬇️ metabolic rate + internal heat prod = ⬇️cold intolerance
⬇️ protein synthesis = brittle nails, thinning hair + dry skin
Depressed reflex activity, slow speech + though processing
Bradycardia
What does the parathyroid hormone (PTH) control?
Blood calcium balance
What does PTH release cause?
Activation of osteoclasts to digest bone matrix to release Ca2+ + phosphate ions into blood.
⬆️ Ca2+ reabsorption + ⬇️ retention of phosphate by kidneys
⬆️ Ca2+ absorption by intestinal mucosa
What does plasma calcium ion homeostasis modulate?
Nerve impulse conduction
Muscle contration
Blood clotting
What does the adrenal medulla secrete?
Catecholamines
Epinephrine
Norepinephrine
What does the adrenal cortex secrete?
Known as the adrenocortical hormones
Mineralocorticoids
Glucocorticoids
Androgens
List the mineralocorticoids the adrenal cortex secretes
Aldosterone
Corticosterone
Deoxycorticosterone
What factors does teenage hypertensions relate to?
⬇️ salt sensitivity
⬆️ sodium intake
⬇️ sensitivity to insulin
What is metabolic syndrome?
Condition in which obesity, high bp, high blood glucose + dyslipidemia clusters together in 1 person.
What are the main organs affected by untreated metabolic syndrome?
Brain
Heart
Pancreas
How can metabolic syndrome be treated?
Weight loss
⬆️ PA
Eat a heart healthy diet = sat fat, cholesterol + salt intake
In which hormones do trained people have elevated response to during PA?
ACTH
Cortisol
