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Anatomy BN2 > Endocrine > Flashcards

Endocrine Flashcards

1
Q

what does the endocrine system regulate?

A 
food intake and digestion
blood glucose
reproduction
labour and lactation
tissue development
water balance
ion regulation
immune system
heart rate and blood pressure
metabolism
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2
Q

what are the 3 chemical messenger classes and what do they do

A
  • Autocrine = influences same cell as secreted it
  • Paracrine = secreted into extracellular fluid & has localised effect on other cells
  • Endocrine = secreted into blood & travels some distance to target tissue
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3
Q

Endocrine glands & cells are all around body- how are they distributed and how doe they relate to the nervous system

A
  • Distribution - Hormones transported in blood to many locations
  • specificity determined by receptor expression at target
  • Concentration of hormone = ∝ strength & magnitude of response
  • Complementary to the nervous system
  • regulation slower (seconds vs ms)
  • but longer lasting (mins/days/weeks)
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4
Q

why is it important that hormones are stable

A

Remain active in circulation long enough to affect specific target tissue & activate specific events

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5
Q

describe water soluble hormones

A

Blood Transport: Large – free in blood, Small – bound to proteins

Half life: Short
(get degraded by proteases in blood)

Examples: Growth hormone, insulin

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6
Q

describe lipid soluble hormones

A

Blood Transport: bound to carrier proteins

Half life: long

Examples: steroid hormones, insulin

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7
Q

what is the pattern of hormone secretion in the following states and what is an example of each:
chronic
Acute
Episodic

A

Chronic = blood concentrations relatively stable
• E.g. thyroid hormone

Acute = blood concentrations variable as hormone released in large amounts in response to stimulus
• E.g. epinephrine in response to stress

Episodic = blood concentrations fluctuate over period
• naturally fluctuate, not in response to stimulus
• E.g. oestrogen in female reproductive cycle

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8
Q

describe the 3 ways hormones ecretion is regulated (humoral, hormonal, neural) with examples

A

Humoral = blood-borne molecules/chemical changes in blood
• E.g. high glucose levels stimulates insulin secretion

Neural = Neurotransmitter released by neuron → stimulates hormone production
o Exercise → autonomic nervous system → adrenal → epinephrine
o Neuropeptide secreted by neuron into blood → stimulates hormone production

Hormonal = hormone secretion → stimulates secretion of another hormone
o E.g. trophic hormones from pituitary stimulate testes to make testosterone

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9
Q

Endocrine diseases are common & characterized by

what 4 things

A
  • disregulated hormone release (a productive pituitary adenoma)
  • inappropriate response to signalling (hypothyroidism)
  • lack of a gland
  • structural enlargement in a critical site such as the thyroid
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10
Q

endocrine diseases can be hypofunction or hyperfunction- describe each

A

• Hypofunction - underfunction: hyposecretion, agenesis, atrophy, or active destruction

Hyperfunction – overfunction: hypersecretion, loss of suppression, hyperplastic or neoplastic change, or hyperstimulation

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11
Q

what are the main structures of the endocrine system?

A 
pineal gland
hypothalmus
pituitary gland
thyroid gland
parathyroid gland
thymus
adrenal glands
pancres
ovary/testes
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12
Q

what organs have secondary endocrine functions

A
  • Kidney
  • Liver
  • Heart
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13
Q

describe the pituitary gland

A
  • Endocrine gland in the brain
  • Pituitary = aka hypophysis
  • 1cm diameter, 0.5-1g
  • Anterior = adenohypophysis
  • Posterior = neurohypophysis
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14
Q

describe the hypothalmus

A
  • Endocrine gland in the brain
  • Lower part of diencephalon
  • Superior to pituitary
  • Hypothalamus connected to pituitary by stalk = infundibulum
  • oversees internal body conditions
  • receives nervous stimuli from receptors throughout body
  • monitors chemical and physical characteristics of blood
  • secretes hormones which regulate pituitary function

Altered homeostasis causes the Hypothalamus to make hormones to stimulate pituitary which Affects hormone release from ant/post pituitary

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15
Q

describe the Hypothalamo-hypophysial tract

A
  • Connects hypothalamus & posterior pituitary
  • communicate via neurons
  • extend through the infundibulum
  • Hypothalamus makes neurohormones
  • pass along neurons in tract
  • Stored in post. pituitary until needed
  • Released from post pituitary when hypothalamus detects need
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16
Q

describe the Hypophysial portal system

A

Connects anterior pituitary to hypothalamus via portal blood vessels
• Creates direct communication
• Eventually portal blood merges with general circulation
Hypothalamus releases hormones, regulate ant. pituitary hormone production
• Ant pit secretes tropic hormones
o stimulate secretion of other hormones

17
Q

describe Pituitary tumours

A
  • Tumors of the adenohypophysis (‘anterior pituitary adenoma’) are common
  • ~15% of intracranial tumors!
  • Often result in hormone overproduction (e.g. growth hormone acromegaly/gigantism) and partial loss of visual field (compression of the optic nerve/chiasm)
  • Pituitary tumors can be operated on through the nasal cavity and sphenoid sinus
18
Q

describe the thyroid gland

A
  • Large = ~20g
  • 2 lobes
  • Anterior to trachea
  • Inferior to thyroid cartilage
  • Connected by isthmus across anterior aspect of trachea
  • Dark red – highly vascularised
  • Regulated by Thyrotropin-releasing hormone (TRH) (hypothalamus) & Thyroid-stimulating hormone (TSH) (ant.Pituitary)
19
Q

describe histology of the thyroid gland

A
  • Many follicles = spheres of single layer cuboidal epithelial cells
  • Produce triiodothyronine (T3) and thyroxine (T4) hormones
  • Stored in & released from follicles in response to TSH from pituitary
  • Iodine needed for Thyroid hormone synthesis – from diet (seafood, dairy, kelp)
  • Parafollicular/C cells produce the hormone calcitonin involved in calcium homeostasis
20
Q

describe the Parathyroid Glands

A
  • 4 small glands on posterior of Thyroid gland made up of 2 cells types:
  • Parathyroid (chief) cells: small, stain darker, produce parathyroid hormone (PTH)
  • Oxyphil cells: large, stain lighter, function unknown
  • Parathyroid glands could be easily damaged/removed by thyroid operations
21
Q

describe Goiter

A

abnormal enlargement of thyroid gland, associated with:

  • hypofunction (e.g. iodine deficiency)
  • hyperfunction (Graves’ disease - autoimmune thyroiditis)
22
Q

what does hypothyroidism cause

A 
decreased metabolic rate
low body temp and cold intolerance
weight gain and decreased appetite
decreased sweat and sebaceous secreations
dry cold skin and coarse hair
decreased heart rate and blood pressure
weak skeletal muscles-sluggish
decreased iodine uptake
?goiter
23
Q

what does hyperthyroidism cause

A 
increased metabolic rate
high body temp and heat intolerance
weight loss and increased appetite
increased sweat and sebaceous secreations
warm flushed skin and soft hair
increased heart rate and blood pressure
weak skeletal muscles-tremors
increased iodine uptake
always goiter
24
Q

what causes hypothyroidism

A
  • Iodine deficiency → inadequate thyroid hormone production → ↑ TSH secretion → goiter as Thyroid overstimulated
  • Neonatal hypothryoidism – maternal iodine deficiency → mental & growth retardation
  • Pituitary insufficiency – lack of TSH secretion
25
Q

what causes hyperthyroidism

A
  • Graves disease – autoimmune disease, TSH immunoglobulin in plasma → goiter
  • Thyroiditis – viral infection → thyroid swelling → ↑ T3 & T4
  • Pituitary tumour → ↑TSH → goiter & ↑ T3 & T4
26
Q

describe adrenal histology

A
  • Inner medulla – makes epinephrine (adrenaline) & norepinephrine (precursor)
  • Outer cortex – 3 layers; makes steroid hormones
  • Cushing’s syndrome: increased cortisol (glucocorticoid) production by adrenal
  • Weight gain, excessive sweating, thin skin
  • caused by pituitary tumour – increased adrenococorticotropic hormone – increased cortisol – Cushings
  • can be artificially produced with immunosuppresive therapy
27
Q

describe the pancreas

A
  • Lies behind peritoneum
  • Between greater curvature of stomach & duodenum
  • 15cm long, 85-100g
  • Exocrine: Acini produce pancreatic juice, carried in duct to small intestine
  • Endocrine: Pancreatic islets secret hormones into circulation
  • Islets of langerhans
  • Regulates nutrient concentration in circulation (insulin & glucagon)
28
Q

describe the pancreatic islets

A
  • ~ 1 million islets of Langerhans in pancreas
  • distributed along exocrine ducts
  • each islet has α, ß, & δ cells

Anatomy BN2 (8 decks)

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