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FOUNDATIONS IN HEALTHCARE > Endocrine system > Flashcards

Endocrine system Flashcards

1
Q

Describe the differences between the endocrine and the nervous system

A

The endocrine system uses chemical messengers called hormones which are released via glands and circulate in the blood, they have a slow & long lasting response. Hormones have a wide spread effect on cells of the body.
The nervous system uses neurones which deliver electrical impulses to muscles & glands, they provide a rapid & short-lived response. Neurones tend to target a specific effector organ of a muscle or gland

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2
Q

What systems does the endocrine system regulate?

A
  • Reproductive system e.g., release of hormones
  • Metabolism e.g., control of insulin & glucagon
  • Osmoregulation e.g., secretion of ADH & ACTH
  • Growth & development e.g., HGH
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3
Q

Describe the function & structure of endocrine glands

A

These are ductless glands that secrete hormones into the bloodstream, endocrine cells are arranged in branched networks & cords to maximize effect with surrounding capillaries

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4
Q

What is an EXOCRINE gland?

A

These are glands that secrete non-hormonal substances e.g., sebum, sweat & salivia. These glands have ducts

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5
Q

Name the main glands involved in the endocrine system

A

Anterior& posterior pituitary gland
Thymus
Thyroid
Parathyroid
Adrenal (cortex + medulla)

The hypothalamus houses pineal & pituitary glands, it is considered a neuroendocrine gland

The testes & ovaries contain endocrine tissue

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6
Q

Describe the function of the hypothalamus in the endocrine system?

A

It is located between the cerebrum & brain stem, housing the pineal & pituitary glands. it is involved in temperature, osmoregulation, sleep, hunger, growth, pleasure & pain
It secretes 5 main hormones of:
- ACTH (adrenocorticotropin)
- TSH (thyrotropin)
- HGH (human growth hormone)
- Gonadotropin
- Somatostatin

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7
Q

What are the functions of the 5 main hypothalamus hormones?

A

ACTH: involved in stimulating adrenal glands to produce sex hormones, corticosteroids & glucocorticoids, involved in the RAS system
TSH: stimulate production of thyroxine from thyroid, controls metabolism, controls O2 reacting with food for ATP synthesis
HGH: stimulates cell growth, reproduction & regeneration, needed for human development
GD: stimulates reproductive organs e.g., testes & ovaries, helps produce sperm & thicken uterine wall
Somatostatin: inhibits release of other hormones. Regulates cell growth & GI tract, can slow digestion and reduce HCL in stomach

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8
Q

What are paracrine & autocrine glands?

A

AC: are short distance travelling chemicals which affect the same cells that secrete them. e.g., prostaglandins in smooth muscle act on smooth muscle
PC: are short distance chemicals which act on different nearby cell types, act within the same tissue,
e.g., signalling nerve to muscle to contract

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9
Q

Describe the structure & function of the anterior pituitary gland

A

Located in the hypothalamus,
(master gland)
It promotes bone & muscle growth
It releases 4 hormones:
FSH:
LH:
ACTH: involved in stimulating cortex of adrenal gland to produce sex hormones, corticosteroids & glucocortoids. It also regulates stress response, suppresses inflammation and regulates metabolism
TSH: (thyroid) stimulates production of thyroxine from thyroid, involved in regulation of metabolism

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10
Q

Describe the structure & function of the posterior pituitary gland

A

The Posterior PG is involved in osmoregulation, it regulates release of ADH which acts on kidney tubules.

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11
Q

Describe the process of osmoregulation/ urine production

A

Water concentration in the blood are detected by osmoreceptors ( maintain homeostasis)
When solute concentration is too high hypothalamic neurones send a signal to the PG, the PG secretes release of ADH to act on the kidney tubules. ADH increases permeability of tubule walls, this allows more water to be selectively reabsorbed. This forms smaller, darker & more concentrated volume of urine. Which is then transported to the bladder to be released from the body via urethra.
Release of ADH stops,
ADH release can be triggered by pressure, pain or drugs

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12
Q

What is the function of oxytocin?

A

Oxytocin produced in the hypothalamus & released by posterior PG, it is released during pregnancy, to stimulate contractions when giving birth (PFS)
It also is involved promoting lactation & promote bonding between baby & mother

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13
Q

What hormones do kidneys release?

A

Kidneys release Renin which is involved in RAS, regulates Na+ & H2O reabsorption. Erythropoietin involved in RBC formation. 1, 25 dihydroxy vitamin D—stimulates calcium absorption from the intestine

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14
Q

What hormones do ovaries release?

A
  • Estrogen involved in regulating menstrual cycle, stimulates breast tissue growth, growth of uterine wall , regulation of cholesterol
  • Progesterone involved in maintaining thickness of uterine lining, prepares uterus for implantation
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15
Q

What hormones do testes release?

A

Testosterone is released from the testes, this is involved with sperm production as well as triggering secondary sexual characteristics during puberty e.g., hair growth, height & genital development. Also aids in bone strength & RBC formation

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16
Q

What hormones do Thymus release?

A

Thymosin- boosts immune response, matures T-cells, stimulates PG hormone production
Thymopoietin- stimulates lymphocytes involved in immune response, aid in fighting infection

17
Q

What is the location & functions of the thyroid?

A

Thryroid is found below the thyroid cartilage & hyoid bone, found between sternocleidomastoid muscle & above trachea
Thyroid regulates metabolism, temperature & growth via release of thyroxine.
It takes up iodine from the blood & converts it to thyroxine & triiodothyronine. This is important for fetal brain development.
Thyroid cells produce calcitonin which lowers levels of Ca2+ & P in blood
Involved in homeostasis

18
Q

Thyroid hormone effect on: basal metabolism, cardiovascular system & nervous system

A

Basal Metabolism: in normal function it promotes normal O2 use & enhances sympathetic NS,
Too low: BMR is below normal, decreased body temp, weight gain, decreases appetite, reduced sensitivity to catecholamines
Too high: BMR higher than normal, increased appetite & weight loss, increases body temp
Cardiovascular system: Promotes normal heart function
Too low: Low HR & BP, reduced effciency
Too high: Increased sensitivity, rapid HR, high BP, palpitations & ultimately heart failure
Nervous system: Normal neuronal development in fetus, normal function in adults
Too low: in infants lack of brain development, adults suffer with depression, memory impairment & hypoactive reflexes
Too high: Irritability, insomnia, graves disease & restlessness

19
Q

Describe the function and location of the parathyroid?

A

It is found within the thyroid gland, containing chief cells that secrete PTH
PTH increases blood calcium levels.
When calcium levels fall it triggers release of PTH
PTH stimulates skeleton, kidneys & intestine. Osteoclasts break down the bony matrix to release Ca to the bloodstream.
Kidney reabsorbs more Ca
Intestine absorbs more vitamin D so more calcium can be reabsorbed

20
Q

Describe the structure & function of the adrenal cortex

A

It consists of 3 layers:
Zona glomerulus: it is the outer layer, produces mineralocorticoids such as aldosterone that are involved in Na+ & H2O concentration in blood
Zona fasciculata: this is the middle layer which produces glucocortoids that reduces inflammation & immune system. reduces effect of stress on the body, regulates blood glucose levels
Zona reticularis: is the inner most layer of the adrenal cortex, it produces sex hormones which are converted to stronger sex hormones e.g., oestrogen

21
Q

Describe the structure & function of the adrenal medulla

A

The adrenal medulla is found surrounded by the adrenal cortex, it produces stress hormones of epinephrine (80%) & norepinephrine (20%).
Epinephrine is a strong stimulator in metabolism & dilation of bronchioles (adrenaline)
Norepinephrine is involved in BP & peripheral NS

22
Q

Describe the short term stress on the adrenal medulla pathway & its short term effects?

A
  1. AP’s are triggered by the hypothalamus due to stressors, activating SNS
  2. AP’s travels along preganglionic sympathetic axons to adrenal medulla
  3. Adrenal medulla secretes epinephrine (80%) & norepinephrine (20%)
  4. Hormones released stimulates SNS responses e.g., dilation of bronchioles & high BP, preparing body for fight of flight
    Short-term effects: blood flow is temporarily redirected to more vital organs & bronchioles dilate. Glycogenolysis occurs
23
Q

Describe the long term stress on the adrenal medulla pathway & its long term effects?

A
  1. Stressors cause releases of CRH from hypothalamus which travels to anterior PG
  2. Anterior PG is triggered to release ACTH
  3. ACTH travels in the blood to adrenal cortex
  4. Adrenal cortex releases glucocorticoids which release cortisol, aldosterone is also released.
    Long term effects: More H2O & Na reabsorbed leading to increased blood volume & pressure. Glucocorticoids reduce immune system & BP
24
Q

Describe the structure & function of the pancreas

A

The pancreas is found between spleen & duodenum
It has exocrine & endocrine glands
endocrine glands secrete glucagon & insulin
Exocrine releases digestive enzymes
Islet of Langerhans has A & B cells which produce hormones

25
Q

Define the function of alpha cells

A

Alpha cells secrete glucagon involved in glycogenolysis & gluconeogenesis. This hormone breaks down stored glycogen into glucose from liver into bloodstream

26
Q

Define the function of beta cells

A

Beta cells secrete insulin which is involved in glycogenesis, it receives glucose from the blood and stores it as glycogen as it enhances transport ability of glucose into cells.
Insulin release inhibits glycogenolysis & gluconeogenesis.

27
Q

What are factors that influence insulin release?

A
  • High blood glucose levels
  • High levels of fattys acids & amino acids
  • ACH release
28
Q

Control of insulin secretion via beta cells:

A

Beta cells contain calcium ion channels which are closed & potassium channels that are open, allowing diffusion of K+ out of cell, giving membrane potential of -70mv

When blood glucose levels rise above normal range Beta cells in the pancreas detect it and secrete insulin

Insulin circulates the bloodstream and stimulates uptake of glucose via muscle, fat & liver cells. These cells contain glucose transporter proteins on their surface membranes

glucose diffuses into cell via transport protein & are respired to produce ATP

ATP causes K+ channels to close, membrane potential becomes more positive

The change in potential difference causes Ca2+ gated channels to open and diffuse down a concentration gradient

The calcium ions cause insulin containing vesicles to move along cytoskeleton & fuse with the plasma membrane, insulin is released via exocytosis

29
Q

The cyclic amp mechanism:

A
  1. The hormone binds to a receptor on the cell surface membrane, this acts as a primary messenger
  2. The binding and changing of receptor shape activates the G protein converting it to active GTP
  3. Activated GTP binds to enzyme adenylate cyclase. Some G proteins inhibit/stimulate AC
  4. GTP is hydrolysed to GDP, G protein becomes inactive,
  5. AC stimulates the secondary messenger of cAMP from ATP
  6. cAMP activates protein kinases, cAMP triggers a cascade of chemical reactions which activates protein kinases to phosphorylate other proteins. Phosphorylation triggers some cell processes & inhibits other processes, e.g., activation of enzymes
30
Q

What are the 3 stimuli for hormone release?

A

Humoral
Neural
Hormonal

31
Q

Describe humoral stimulus on endocrine system

A

Hormone release is triggered by concentration of nutrients & ion concentration
E.g., low Ca2+ triggers the release of PTH from the parathyroid gland which increases blood calcium, by acting on intestine ,skeleton & kidneys

32
Q

Describe neural stimulus on endocrine system

A

Hormones are released via neural stimulus. APS in preganglionic sympathetic fibres travel to the adrenal medulla causing adrenaline & noradrenaline to be secreted into bloodstream
(fight/flight)

33
Q

Describe hormonal stimulus on the endocrine system

A

The release of a hormone is triggered by the release of another hormone
Hormones are released from the anterior pituitary gland which stimulates other glands e.g., thyroid or ovaries to secrete hormones

FOUNDATIONS IN HEALTHCARE (11 decks)

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