the endocrine system

Question 1

what is the endocrine system

Answer 1

glands or organs that secrete hormones (chemical messengers), glands are typically ductless (e.g. pituitary), other organs can release hormones (pancreas), secrete hormones into the blood system, excite or inhibits activity of other organ or tissue

Question 2

what are target organ cell

Answer 2

what hormones are directed to

Question 3

other systems that produce hormones

Answer 3

stomach- gastrin, small intestine- peptides secretin, kidney- erythropoietin

Question 4

main functions of endocrine system

Answer 4

sodium and water balance- blood volume, calcium and phosphate balance, energy balance and control of macronutrient (lipid, glucose) utilisation and storage, responses to stress, reproduction, sexual development and growth

Question 5

categories of hormones- non-steroidal hormones

Answer 5

attach to specefic membrane receptors and work by secondary messenger mechanism. they are whole proteins, with shorter chains of amino acids

Question 6

how do non-steroidal hormones work

Answer 6

work as lock and key concept. once hormones attach, chemical reactions occur, activate molecules within the cell to do things (secondary messengers). these cause further reactions and may secrete more hormones

Question 7

categories of hormones- steroidal hormones

Answer 7

small lipid soluble hormone can pass through the cell membrane of the target organ. the chemical structures affects where it can travel within the body.

Question 8

how do steroidal hormones work

Answer 8

once inside they pass through cytoplasm and enter nucleus, then bind to receptor in nucleus, forming hormone receptor complex- cause DNA of cell to do specific things (alters activity). usually much slower

Question 9

non-steirod hormones- protein or peptide hormones

Answer 9

majority of hormones, vary in size, they are synthesised as prrehormones, in which they undergo transformation at required time, stored I secretary glands and are exocystose from the cell
e.g. insulin, glucagon

Question 10

non-steirod hormones- amino acid derived hormones

Answer 10

synthesised from other amino acids. e.g. adrenaline and noradrenaline

Question 11

steroidal hormones- cholesterol

Answer 11

derived from cholesterol and synthesised in adrenal cortex, glands and placenta
lipid soluble (able to cross cell membrane) require binding proteins in blood
e.g. testosterone, oestrogen

Question 12

pathways to hormone effect- paracrine pathway

Answer 12

hormones produced in a cell, secreted, act directly on nearby receptive cells, e.g. histamine

Question 13

pathways to hormone effect- autocrine pathway

Answer 13

cell is able to produce hormone and every effect on itself, receptor cells are also secretory cells

Question 14

pathways to hormone effect- endocrine (AKA telecrine) pathway

Answer 14

hormones produce in a cell , secreted and travel through blood vessels to distant cells, attach to receptor, act on cell

Question 15

pathways to hormone effect- synaptic pathway

Answer 15

hormones produced within neurone, secreted and travel along axon to synapse where they are released and take up by nearby neurone with appropriate receptors to exert an effect

Question 16

pathways to hormone effect- neuroendocrine pathway

Answer 16

hormones produced in neurone, secreted along axon to synapse, released, taken up into vascular system, travel to distant cells with appropriate receptors to exert an effect

Question 17

the hypothalamus

Answer 17

contains neurones that synthesise inhibiting and releasing hormones to act on pituitary gland. common releasing hormones from the hypothalamus- Growth hormone RH, thyrotropin RH, (thyroid stimulating hormone), corticotrophin (triggers release of cortical), gonadotropin RH- produce reproductive hormones, all stimulate pituitary gland

Question 18

common releasing hormones from hypothalamus

Answer 18

Growth hormone RH, thyrotropin RH, (thyroid stimulating hormone), corticotrophin (triggers release of cortical), gonadotropin RH- produce reproductive hormones, all stimulate pituitary gland

Question 19

pituitary gland

Answer 19

responds to hypothalamic triggers and acts accordingly

Question 20

what are feedback mechanisms

Answer 20

what triggers hypothalamus or pituitary to initiate a hormone release? all provide input to the hypothalamus to regulate bodily functions. this occurs through negative and positive feedback loops

Question 21

examples of feedback mechanisms

Answer 21

neurotransmitters, injury, release of chemical mediators after injury, neuroendocrine signals

Question 22

regulation of hormone secretion- negative feedback loop

Answer 22

most common mechanism. affected by environmental and body temperature, stress, nutrition and precedes of specific body substances
e.g. thyroid hormone or insulin and blood sugar level

Question 23

regulation of hormone secretion- positive feedback loop

Answer 23

uncommon. amplify changes rather than reverse them, precedes of hormone stimulates increased production of the hormone until there is an interruption in the cycle
e. g. oxytocin at birth

Question 24

causes of altered hormone function

Answer 24

impairment of the hypothalamus or pituitary gland, endocrine gland
too little/ much hormone produced or secreted,
inactive hormone receptor binding
lack of responses by target cell to hormone
impaired negative feedback loop
hormone produced ecotopically
impaired hormone metabolism

Question 25

disorders of the endocrine system

Answer 25

acromegaly- pituitary gland produces too much GH )big bony features) gigantism, achondroplasia- too little GH at childhood- problem with pituitary gland, hyper/hypothyroidism, Cushing syndrome

Question 26

thyroid

Answer 26

butterfly shape gland on anterior part of neck, critical role in stimulation mechanism, facilitates breakdown of carbohydrates (proteins, fats for energy, stimulation of heart, and glucose production)
production of structural proteins, enzymes and other hormones
promotes growth and development in children

Question 27

thyroid hormone

Answer 27

thyroidtropin releasing hormone- from hypothalamus stimulates thyroid to release thyroid stimulating hormone, thyroid stimulating hormone= more released,

Question 28

what are the 2 thyroid hormone

Answer 28

thyroxine- T4

Triiodothyroinene- T3

Question 29

What does thyroid hormone do

Answer 29

increased glucose absorption, release lipids from adipose tissue, metabolism of proteins from muscle tissue, increased cholesterol breakdown in the liver, increased oxygen consumption, increased heat production, increased CO, increased gastric motility, increased muscle tone and reactivity, increased activation of cognitive processes

Question 30

disorders of the thyroid- hyperthyroidism

Answer 30

excessive thyroid hormone produced, due to:
increased stimulation of thyroid gland, disease of thyroid gland, increased production of TSH by a pituitary tumor, some medications containing high levels of iodine, health food supplements containing seaweed

Question 31

disorders of the thyroid- hypothyroidism

Answer 31

deficient thyroid hormone- congenital or acquired

Question 32

hypothyroidism- congenital

Answer 32

congenital- occurs during foetal development, lack of thyroid development/ hormone, in utero, maternal T4 crosses placenta, so baby appears normal, results in developmental delaysy and impaired growth,

Question 33

acquired hypothyroidism

Answer 33

due to autoimmune disorder, iodine deficiency, surgical removal or radiation therapy to thyroid gland, medications that destroy gland and genetic defects
more common in women than men

Question 34

what is myxoedema

Answer 34

unique to hypothyroidism, boggy, oedematous tissue, especially in the face, hands, feet

Question 35

how is hypothyroidism treated

Answer 35

treated by replacement hormone therapy, and elevation of clinical signs

Question 36

Symptoms of hypothyroidism

Answer 36

don’t feel like they want to do anything, cold interolrant, weight gain, dry skin, brittle hair, effects person fertility, feel like they can’t remember things,