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NURX1003 > The Endocrine System > Flashcards

The Endocrine System Flashcards

1
Q

Nervous system - consists

A
  1. (The nervous system controls homeostasis through the release of neurotransmitters; the endocrine system uses hormones)
  2. (The nervous system causes muscles to contract and glands to secrete; the endocrine system affects virtually all body tissues)
  3. Exocrine glands secrete their products through ducts into body cavities or into body surfaces
  4. (The endocrine system consists of endocrine glands and several organs that contain endocrine tissue)
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2
Q

Functions of hormones

A
  1. Help regulate –
    chemical composition and volume of internal environment
    metabolism and energy balance
    contraction of smooth and cardiac muscle fibres
    glandular secretions
    some immune system activities
  2. Control growth and development
  3. Regulate operation of reproductive systems
  4. Help establish circadian rhythms
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3
Q

Comparison of control by the nervous and endocrine system

A
  1. Mediator molecules –
    nervous system – neurotransmitters released locally in response to nerve impulses
    endocrine system – hormones delivered to tissues throughout body by blood
  2. Site of mediator action –
    nervous system – close to site of release, st synapse, binds to receptors in postsynaptic membrane
    endocrine system – far from site of release, binds to receptors on or in target cells
  3. Types of target cells –
    nervous system – muscle (smooth, cardiac, skeletal) cells, gland cells and other neurons
    endocrine system – cells throughout the body
  4. Time to onset of action –
    nervous system – typically within milliseconds
    endocrine system – seconds to hours or days
  5. Duration of action –
    nervous system – generally briefer
    endocrine system – generally longer
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4
Q

Hormone action

A
  1. (Endocrine glands secrete hormones into interstitial fluid, then the hormones diffuse into the blood)
  2. Hormones affect only specific target cells that have the proper receptors to bind a given hormone
  3. Chemically hormones are either lipid soluble or water soluble
  4. Lipid soluble hormones affect cell function by altering general expression
  5. Water soluble hormones after cell function by activating plasma membrane receptors which click to production of a second messenger that activates various proteins inside the cell
  6. Hormone secretion is controlled by signals from the nervous system chemical changes in the blood and other hormones
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5
Q

Hypothalamus and pituitary gland

A
  1. The pituitary gland is attached to the hypothalamus and consists of two lobes, the anterior pituitary and the posterior pituitary. hormones of the pituitary gland are controlled by inhibiting and releasing hormones produced by the hypothalamus. the hypophyseal portal veins carry hypothalamic releasing and inhibiting hormones from the hypothalamus to the anterior pituitary
  2. The anterior pituitary consists of cells that reduce human growth hormones, prolactin, thyroid stimulating hormones, follicle stimulating hormone, luteiniizing hormone, adrenocorticotropic hormones, melanocyte stimulating hormone
  3. Human growth hormone stimulates body growth through insulin like growth factors and is controlled by growth hormones releasing hormone and growth hormone inhibiting hormones
  4. TSH regulates thyroid gland activities and is controlled by thyrotropin releasing hormone
  5. FSH and LH regulate activities of the gonads, ovaries and testes and controlled by the gonadotropin releasing hormone
  6. PRL helps stimulate milk production, prolactin inhibiting hormone suppresses release of prolactin and prolactin releasing hormone stimulates a rise in prolactin level during pregnancy
  7. ACTH regulates activities of the adrenal cortex and is controlled by corticotropin releasing hormone
  8. The posterior pituitary contains axon terminals of neuro secretory cells whose cell bodies are in the hypothalamus. hormones made in the hypothalamus are released in the posterior pituitary include oxytocin, which stimulates contraction of the uterus and ejection of milk from the breasts and anti diuretic hormone which stimulates water reabsorption by the kidneys and constriction of arterioles
  9. Oxytocin secretion is stimulated by uterine stretching and by suckling during nursing, adh secretion is controlled by the osmotic pressure of the blood and blood volume
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6
Q

Regulation of secretions and actions of antidiuretic hormone

A
  1. High blood osmotic pressure stimulates hypothalamic osmoreceptors
  2. Osmoreceptors activate the neuroseretory cells that synthesise and release ADH
  3. Nerve impulses liberate ADH from axon terminals in the posterior pituitary into the bloodstream
  4. Kidneys retain more water, which decreases urine output
  5. Low blood osmotic pressure inhibits hypothalamic osmoreceptors
  6. Inhibition of osmoreceptors reduces or stops ADH secretion
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7
Q

Pituitary gland hormones and their actions - anterior pituitary hormones

A
  1. Human growth hormone – stimulates liver, muscle, cartilage, bone and other tissues to synthesise and secrete insulin like growth factors (IGF). IGF promote growth of body cells, protein synthesis, tissue repair, breakdown of triglycerides and elevation of blood glucose level
  2. Thyroid stimulating hormone – stimulates synthesis and secretion of thyroid hormones by the thyroid gland
  3. Follicle simulating hormone – in females initiates development of locates and induces secretion of oestrogens by the ovaries, in males stimulates testes to produce sperm
  4. Luteinizing hormone – in females stimulates secretion of oestrogens and progesterone, ovulation and formation of leuteum, in males stimulates testes to produce testosterone
  5. Prolactin – in females stimulates milk production by the mammary glands
  6. Corticoptropin hormone – stimulates secretion of glucocorticoids by the adrenal cortex
  7. Melanocyte stimulating hormone – exact role in humans is unknown but my influence brain activity when present in excess can cause darkening of skin
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8
Q

Pituitary gland hormones and their actions - posterior pituitary hormones

A
  1. Oxytocin – stimulates contraction of smooth muscle cells of uterus during childbirth, stimulates milk ejection from mammary glands
  2. Antidiuretic hormone – conserves body water by decreasing urine output, decreases water loss through sweating, raises blood pressure by restricting arterioles
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9
Q

Thyroid gland

A
  1. The thyroid gland located below the larynx consists of thyroid follicles composed of follicular cells which secrete the thyroid hormones thyroxine and triiodothyronine and parafollucular cells which secrete calcitonin
  2. Thyroid hormone regulate oxygen use and metabolic rate, cellular metabolism and growth and development. secretion is controlled by TRH from the hypothalamus and thyroid stimulating hormone from the anterior pituitary
  3. Calcitonin can lower the blood level of calcium its secretion is controlled by the level of calcium in the blood
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10
Q

Regulation of the secretion of thyroid hormones

A
  1. Low blood levels of thyroid hormones or low metabolic rate stimulate release of hypothalamus to release TRH
  2. TRH carried by hypophyseal portal veins to anterior pituitary stifles release of tsh
  3. TSH released into blood stimulates thyroid follicular cells
  4. Thyroid hormones released into blood by follicular cells
  5. Elevated levels of thyroid hormones inhibits release of TRH and TSH
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11
Q

Parathyroid glands

A
  1. The parathyroid glands are embedded on the posterior surfaces of the thyroid
  2. Parathyroid hormone regulates the homeostasis of calcium, magnesium and phosphate by increasing blood calcium and magnesium levels and decreasing blood phosphate levels. pth secretion is controlled by the level of calcium in the blood
  3. High levels of Ca2+ in blood stimulates thyroid gland parafollicular cells to release more CT
  4. Calcitonin inhibits osteoclasts decreasing blood Ca2+ level
  5. Low level of Ca2+ in blood stimulates parathyroid gland chief cells to release more pth
  6. Parathyroid hormone promotes release of Ca2+ from bone extracellular matrix into blind and slows loss of Ca2+ in urine increasing blood Ca2+ level
  7. PTH also stimulates the kidneys to release calcitriol
  8. Calcitriol stimulates increased absorption of Ca2+ from foods which increases blood Ca2+ level
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12
Q

Pancreatic islets

A
  1. The pancreas lies in the curve of the duodenum, it has both endocrine and exocrine functions
  2. The endocrine portion consists of pancreatic islets or islets of langerhans which are made up of alpha and beta cells
  3. Alpha cells secrete glucagon and beta cells secrete insulin
  4. Glucagon increases blood glucose level and insulin decreases blood glucose level, secretion of both hormones is controlled by the level of glucose in the blood
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13
Q

Regulation of blood glucose level by negative feedback systems involving glucagon and insulin

A
  1. Low blood glucose (hypoglycaemia) stimulates alpha cells to secrete glucagon
  2. Glucagon acts on liver cells to –
    convert glucagon into glucose
    form glucose from lactic acid and certain amino acids
  3. Glucose released by liver cells raises blood glucose level to normal
  4. If blood glucose continues to rise hyperglycaemia inhibits the release of glucagon
  5. High blood glucose (hyperglycaemia) stimulate beta cells to secrete insulin
  6. Insulin acts on various body cells to –
    accelerate facilitated diffusion of glucose into cells
    speed conversion of glucose to glucagon
    increase uptake of amino acids and increase protein synthesis
  7. Blood glucose level fall
  8. If blood glucose continues to fall, hypoglycaemia inhibits release of insulin
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14
Q

Adrenal gland

A
  1. The suprarenal glands are located above the kidneys, they consist of an outer cortex and inner medulla
  2. The adrenal cortex is divided into three zones, the outer zone secrets mineralocorticoids, the middle zone secretes glucocorticoids, and the inner zone secretes androgens
  3. Mineralocorticoids increase sodium and water reabsorption and decease potassium reabsorption, secretion is controlled by the renin angiotensin aldosterone pathway
  4. Glucocorticoids promote normal metabolism, help resist stress and decrease inflammation and secretion is controlled by acth
  5. Androgens secreted by the adrenal cortex stimulate growth of auxiliary and pubic hair, and the prepubertal growth spurt, and contribute to libido
  6. The adrenal medulla secrete epinephrine and norepinephrine which are released under stress
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15
Q

The renin engiotensin aldosterone pathway

A
  1. Dehydration, Na+ deficiency or haemorrhage
  2. Decrease in blood volume and pressure
  3. Angiotensin 1
  4. Angiotensin 2
  5. In kidneys more na+ and water return to blood and more K+ eliminated in urine
  6. Increase blood volume and pressure
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16
Q

Ovaries and testes

A
  1. The ovaries are located in he pelvic cavity and produce oestrogens, progesterone and inhibiting, these sex hormones regulate the menstrual cycle, maintain pregnancy and prepare the mammary glands for lactation, they also help establish and maintain the feminine body shape
  2. The testes lie inside the scrotum and produce testosterone and inhibin, testosterone regulates production of sperm and stimulates the development and maintenance of masculine characteristics such as beard growth and deepening of the voice
17
Q

Pineal gland

A
  1. The pineal gland attached to the rood of the third ventricle in the brain secretes melatonin which contributes to setting the body’s biological clock
18
Q

The stress response - thymus

A
  1. Thymosin – promotes the maturation of T cells and may retard the ageing process
19
Q

The stress response - gastrointestinal tract

A
  1. Gastrin – promotes secretion of gastric juice and increases movements of the stomach
  2. Glucose dependent insulinotropic peptide – stimulates release of insulin by pancreatic beta cells
  3. Secretin – stimulates secretion of pancreatic juice and bile
  4. Cholecystokinin – stimulates secretion of pancreatic juice, regulates release of bile from the gallbladder and brings about a feeling of fullness after eating
20
Q

The stress response - kidney

A

Erythropoietin – increases rate of red blood cell production

21
Q

The stress response - heart

A

Atrial natriuretic peptide – decreases blood pressure

22
Q

The stress response - adipose tissue

A

Leptin – suppresses appetite and may increase activity of FSH and LH

23
Q

The stress response - placenta

A

Human chorionic gonadotropin – simulates the ovary to continue production of oestrogens and progesterone during pregnancy

24
Q

Stress response

A
  1. Stressors include surgical operations, poisons, infections, fever and strong emotional responses
  2. If stress is extreme it triggers the stress response which occurs in three stages, the fight to flight reps once, resistance reaction and exhaustion
  3. The fight to flight response is instead by nerve impulses from the hypothalamus to the sympathetic division of the autonomic nervous system and the adrenal medulla, his response rapidly increases circulation and promotes ATP production
  4. The resistance reaction is instead by released hormones created by the hypothalamus, resistance reactions are longer lasting an accelerate breakdown reactions to provide ATP for counteracting stress
  5. Exhaustion results from depletion of body resources during the resistance stage
  6. Stress may trigger certain diseases by inhibiting the immune system
25
Q

The pancreas and diabetes - pancreatic islets

A
  1. The pancreas lies in the curve of the duodenum, it has both endocrine and exocrine functions
  2. The endocrine portion consists of pancreas islets made up of alpha and beta cells
  3. Alpha cells secrete glucagon and beta cells secrete insulin
  4. Glucagon increases blood glucose level and insulin decreases blood glucose level, secretion of both hormones is controlled by the level of glucose in the blood
26
Q

Blood glucose regulation

A
  1. If the blood glucose level is too low the pancreas stops producing insulin and produces glucagon. the production of glucagon will signal the liver to release the glucose in glucagon so your body can use it
  2. If the blood glucose level is too high the pancreas secretes insulin. insulin moves through the body and triggers fat cells to take in blood glucose and then signals the liver to store the glucose as glucagon

NURX1003 (24 decks)

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