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Endocrine system Flashcards

1
Q

What makes up the endocrine system?

A

All of the body’s different endocrine glands, tissues, and hormones

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2
Q

What is the role of the endocrine system?

A

To regulate many biological processes in the body

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3
Q

How do hormones work?

A
  1. secreted from endocrine gland
  2. carried in blood to target cells where it binds to specific receptor for that hormone on membrane or in cell
  3. causes change in activity of cell
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4
Q

How many amino acids in a peptide hormone?

A

typically less than 50

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5
Q

How many amino acids are in a polypeptide hormone?

A

Typically more than 50

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6
Q

What are key features of protein/peptide hormones?

A
  1. water soluble
  2. non-lipid
  3. cannot cross phospholipid bilayer of target cells so must bind to receptor on its surface
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7
Q

What happens after a protein/peptide hormone has bound to the target cell?

A

Triggers a series of messengers inside the cell which coordinates a response in the cell to switch genes on/off to affect the cell’s activity

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8
Q

What are the key features of steroid hormones?

A
  1. lipid soluble
  2. synthesised from cholesterol
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9
Q

How do steroid hormones work?

A
  1. diffuse through target cell membrane
  2. form receptor-hormone complex with a receptor in the cytoplasm
  3. complex moves into nucleus and binds to DNA which activates genes
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10
Q

What are amine hormones synthesised from?

A

amino acids tryptophan and tyrosine

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11
Q

What processes are amine hormones involved in?

A

stress response, metabolism

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12
Q

How are endocrine glands stimulated?

A
  1. hormonal - another hormone binds to the cell
  2. humoral - fluctuation in ion/nutrient in blood
  3. neural - nerve from brain directly stimulates gland
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13
Q

What are the major endocrine glands?

A

1, hypothalamus
2. pineal gland
3. pituitary gland
4. thyroid gland
5. parathyroid gland
6. adrenal glands
7. islet of Langerhans in pancreas
8. ovary
9. testes

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14
Q

What is the hypothalamus?

A

A region of the brain located directly above the brainstem which is responsible for most endocrine control in body

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15
Q

Where is the pituitary gland?

A

In the pituitary fossa of the skull connected to the hypothalamus by the infundibulum

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16
Q

What does the pituitary gland do?

A

Releases several important hormones but is under the control of the hypothalamus

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17
Q

What is the pituitary gland known as?

A

master endocrine gland

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18
Q

What are the lobes of the pituitary gland?

A
  1. anterior pituitary (adenohypophysis)
  2. posterior pituitary (neurohypophesis)
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19
Q

How is the posterior pituitary formed?

A
  1. from neural (brain) tissue
  2. in embryonic development, a bundle of nerves extend from the hypothalamus to form and outgrowth -> posterior pituitary
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20
Q

What does the posterior pituitary do?

A
  1. stores hormones produced by hypothalamus (oxytocin and ADH)
  2. releases these hormones when signalled by hypothalamus into the bloodstream
  3. regulated directly by hypothalamus
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21
Q

How is the anterior pituitary gland formed?

A
  1. In embryonic development
  2. Derived from tissues in roof of mouth which bud off, migrate to, and integrate with the hypothalamus
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22
Q

What does the anterior pituitary do?

A
  1. hypothalamic neurons secrete hormones into anterior pituitary
  2. act on relevant groups of cells to inhibit or stimulate them
  3. produces hormones which act on various locations in the body
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23
Q

What hormones does the anterior pituitary produce?

A
  1. Thyroid stimulating hormone (TSH)
  2. Growth hormone (GH)
  3. Adrenocorticotrophic hormone (ACTH)
  4. Follicle stimulating hormone (FSH)
  5. Luteinising hormone (LH)
  6. Prolactin
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24
Q

What does thyroid stimulating hormone (TSH) do?

A

Stimulates thyroid to produce thyroid hormone

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25
Q

What does adrenocorticotrophic hormone (ACTH) do?

A

stimulates the adrenal cortex to secrete its hormones

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26
Q

What does follicle stimulating hormone (FSH) do?

A

regulates functions of gonads (ovaries and testes)

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27
Q

What does luteinising hormone (LH) do?

A

regulates functions of gonads (ovaries and testes)

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28
Q

What does prolactin do?

A

stimulates milk production in mammary gland

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29
Q

Where is the thyroid gland?

A

In neck region at C6-8 and T1 vertebrae

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30
Q

What are the features of the thyroid gland?

A
  1. butterfly shaped with 2 lobes
  2. lobes joined by isthimus
  3. each lobe 5cm by 3cm
  4. highly vascularised
  5. most cells are cuboidal epithelial (follicular cells)
  6. c-cells are inbetween these which are imp for regulating calcium levels
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31
Q

What are the functions of the thyroid gland?

A
  1. produce thyroid hormone (TH)
  2. produce calcitonin hormone
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32
Q

What does thyroid hormone (TH) do?

A

controls metabolism of glucose to form heat and energy so controls basal metabolic rate

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33
Q

What does calcitonin hormone do?

A

is secreted from c-cells when blood calcium is too high, and lowers it

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34
Q

How is thyroid hormone released?

A
  1. hypothalamus stimulates pituitary with TRH
  2. pituitary releases TSH
  3. TSH stimulates release of TH when binds to thyroid
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35
Q

What are the variations of thyroid hormone?

A
  1. Thyroxine (T4) - 4 atoms of iodine, amine, more abundant but less potent
  2. Tri-iodothyronine (T3) - 3 atoms of iodine
36
Q

How do T3 and T4 affect the body?

A
  1. increase metabolic rate and heat production
  2. regulate metabolism of carbs, proteins, fats
  3. essential for normal growth and development
  4. needed for healthy brain function
37
Q

How does thyroid hormone level fluctuate throughout the day?

A
  1. highest after waking up to start body metabolism and energy production for the day
  2. decline in afternoon and evening
38
Q

How is thyroid hormone regulated?

A
  1. TH level detected by hypothalamus
  2. Inhibits TRH from hypothalamus, which inhibits TSH
  3. Anterior pituitary also senses elevation and reduces release
  4. Fluctuations are tied to circadian rhythms
39
Q

What is hyperthyroidism?

A

Overactive thyroid gland resulting in overproduction of T4 and T3

40
Q

What can hyperthyroidism be caused by?

A
  1. Graves disease - an autoimmune disease
  2. Excessive iodine intake
  3. Certain medications
41
Q

What are the effects of hyperthyroidism?

A
  1. Increased basal metabolic rate
  2. Weight loss
  3. Increased appetite
  4. Anxiety and restlessness
  5. High heart rate, palpitations, atrial fibrillation
  6. Increased respiratory rate
  7. Warm sweaty skin
42
Q

What are the effects of hypothyroidism?

A
  1. decreased metabolic rate
  2. weight gain
  3. depression
  4. lethargy
  5. fluid retention
  6. dry, cold skin
  7. slow heart rate
43
Q

How can hyperthyroidism affect speech?

A
  1. high pitched tremulous voice
  2. uneven intonation
  3. vocal fatigue
  4. swelling of thyroid can compress trachea and cause dysphagia
44
Q

How can hypothyroidism affect speech?

A
  1. retarded laryngeal development and muscle atrophy -> weak voice
  2. oedema in vocal tract -> incomplete closure of larynx in phonation and poor articulation from swelling in tongue and lips
  3. swelling of thyroid can compress trachea and cause dysphagia
45
Q

How does calcitonin work?

A

Inhibits activity of osteoclasts (which break down bone) so lowers blood calcium

46
Q

What are the parathyroid glands?

A

Two glands on each of the posterior thyroid lobes which secrete parathyroid hormone

47
Q

What does parathyroid hormone do?

A
  1. released when there is low calcium
  2. stimulates osteoclasts
  3. stimulates kidneys to reabsorb calcium back into blood
  4. increases active vitamin D levels
48
Q

What causes excess parathyroid hormone production?

A

tumours in the gland

49
Q

What will excess parathyroid hormone production cause?

A
  1. high calcium levels in blood
  2. low calcium in bones
  3. weak bones
50
Q

What is low parathyroid hormone production caused by?

A
  1. removal or damage to gland in surgery
  2. developmental disorder affecting pharyngeal arches
51
Q

What are the effects of low parathyroid hormone?

A
  1. hypocalcaemia
  2. tetanic muscle spasms
  3. tetany of laryngeal and respiratory muscles -> asphyxia
  4. potentially fatal
52
Q

What is growth hormone?

A

A large protein hormone which stimulates growth and division of cells in bone and skeletal muscle

53
Q

How does growth hormone work?

A
  1. stimulates liver to produce insulin-like growth factor
  2. IGF stimulates protein synthesis for growth and repair
  3. growth hormone promotes breakdown of fats
54
Q

When is growth hormone release highest?

A

When sleeping

55
Q

What can cause excess growth hormone?

A

Usually a benign pituitary tumour that secretes excessive growth hormone

56
Q

What are the effects of excess growth hormone?

A
  1. in childhood - excessive growth in height and body size in development (gigantism)
  2. in adults - enlarged facial features, hands, feet, thick oily skin, skin tags, excessive sweating (acromegaly)
57
Q

What causes growth hormone deficiency?

A

Cause often unknown, may be genetic mutations, brain tumours, infections

58
Q

What are the effects of growth hormone deficiency?

A
  1. in childhood - stunted growth, delayed development of secondary sexual characteristics, shorter stature
  2. in adults - reduced muscle mass, increased body fat, decreased bone density
59
Q

How can agromegaly affect speech?

A

Can lead to enlarged tongue, vocal cords and dental changes which may affect speech clarity and articulation

60
Q

Where are the adrenal glands?

A

On top of kidney and enclosed within renal fascia

61
Q

What are the parts of the adrenal gland?

A
  1. adrenal cortex
  2. adrenal medulla
62
Q

What are the adrenal functions?

A
  1. involved is stress response - emotional states, disease, surgery, trauma, sleep deprivation
  2. involved in blood pressure regulation
  3. secrete small amounts of sex hormones
63
Q

What happens when the anterior pituitary releases adrenocorticotrophic (ACTH) hormone?

A
  1. hypothalamus simultaneously releases corticotrophin releasing hormone (CRH) in stress
  2. ACTH travels in blood to adrenal cortex
  3. stimulates secretion of glucocorticoids
64
Q

What are the main glucocorticoids?

A
  1. cortisol
  2. corticosterone
65
Q

What do glucocorticoids do?

A
  1. increase blood glucose levels
  2. inhibit action of insulin
  3. increase protein and lipid availability
66
Q

What is the Hypothalamic-Pituitary-Axis?

A

A negative feedback loop by which when cortisol (stress hormone) levels rise, Corticotrophin Releasing Hormone (CRH) is inhibited, which reduces release of Adrenocorticotrophic Hormone (ACTH)

67
Q

What is aldosterone?

A

A mineralcorticoid hormone released from adrenal cortex

68
Q

How is the release of aldosterone stimulated?

A

Kidneys release angiotensin II when there is low blood pressure which stimulates its productions

69
Q

What does aldosterone do?

A
  1. stimulate nephrons to increase reuptake of sodium into filtrate of blood
  2. cause secretion of potassium from blood into nephron
  3. this all causes water to follow the sodium passively by osmosis to increase blood volume and pressure
70
Q

What does the adrenal medulla develop from?

A

nervous tissue in the embryo - is part of the sympathetic nervous system

71
Q

What hormones does the adrenal medulla release?

A
  1. adrenaline
  2. noradrenaline
    amine hormones both known as catecholamines
72
Q

What is the function of adrenaline?

A
  1. Released quickly by neural control of hypothalamus
  2. Release short burst of ATP to mobilise muscle
  3. Increase cardiac activity and muscle glucose levels
73
Q

What is the function of noradrenaline?

A
  1. increase blood pressure
  2. neurotransmitter in CNS
74
Q

What is Addison disease

A
  1. auto-immune disease affecting adrenal cortex
  2. hypo-secretion of cortisol
  3. causes increase in ACTH production
  4. causes abnormal skin pigmentation, fatigue, weight loss, low blood pressure
75
Q

What is Cushing’s syndrome?

A
  1. high cortisol
  2. often due to steroid medication or pituitary gland adenoma
  3. increased appetite and weight gain
  4. increased blood pressure and fluid retention
76
Q

How can testosterone affect speech?

A

can increase size of thyroid cartilage in larynx -> more prominent adams apple, elongated vocal folds -> lower pitch

77
Q

What does FSH do in females?

A

Stimulates oestrogen secretion from ovary, and maturation of follicle in menstrual cycle

78
Q

What does LH do in females?

A

Promotes ovulation and secretion of progesterone from ovary

79
Q

What does FSH do in males?

A

regulates sperm maturation in testes

80
Q

What does LH do in males?

A

stimulates testes to secrete testosterone

81
Q

What does testosterone do?

A

Promotes growth and maturation of reproductive organs and continued sperm production throughout life

82
Q

What does oxytocin do?

A

Stimulates powerful muscular contractions of uterus in labour, and milk ejection in breastfeeding
Acts as a positive feedback mechanism

83
Q

What does antidiuretic hormone (ADH) do?

A
  1. inhibits urine production by making the kidneys reabsorb more water
  2. large amounts constrict arterioles sol increase blood pressure
84
Q

What hormones are produced by the islet of langerhans?

A

insulin and glucagon

85
Q

What does insulin do?

A

Binds to muscle and liver cells to make them take up glucose from blood and store it as glycogen

86
Q

What does glucagon do?

A

Binds to the liver cells causing them to break down glycogen to glucose when blood glucose is low

Biomed (29 decks)

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