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Intro Anatomy > Endocrine System > Flashcards

Endocrine System Flashcards

1
Q

Endocrine system

A
  • endocrine system and nervous system work together
  • endocrine system:
    • hormones released into bloodstream travel throughout body
    • results may take hours but last longer
  • nervous system
    • releases neurotransmitters to excite or inhibit nerve, muscle and gland cells
    • results in milliseconds, brief duration of effects
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2
Q

Hormone receptors

A

-hormones only affect target cells with specific membrane proteins called receptors

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3
Q

Role of hormone receptors

A
  • constantly being synthesized and broken down
  • a range of 2000-100,000 receptors/ target cells
  • up-regulation:
    • deficiency of hormone, produces and increased number of receptors to up take more
    • target tissue more sensitive to hormone
  • down regulation
    • excess hormone, produces a decrease in number of receptors
    • receptors undergo endocytosis and are degraded
    • decreases sensitivity of target cell hormone
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4
Q

Hypothalamus and pituitary gland

A
  • both are master endocrine glands wince their hormones control other endocrine glands
  • hypothalamus receives input from cortex, thalamus, limbic system and internal organs
  • hypothalamus is connected to pituitary gland by a stalk called the infundibulum
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5
Q

Anatomy of pituitary gland

A
  • pea shaped gland found in sella turcica of sphenoid
  • infundibulum attaches it to brain
  • anterior lobe: 75%
    • connected to hypothalamus by portal veins
  • posterior lobe: 25%
    • ends of axons of neurons found in hypothalamus
    • stores and releases neurotransmitters/hormones into blood stream
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6
Q

Flow of blood to anterior pituitary

A
  • controlling hormones enter blood
  • travel through portal veins
  • enter anterior pituitary at capillaries
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7
Q

Anterior pituitary (adenophypophysis) secretions

A
  • 7 major hormones secreted by 5 cell types:
    • HGH
    • TSH
    • ACTH
    • FSH
    • LH
    • PRL
    • MSH
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8
Q

Human growth hormone (anterior pituitary)

A
  • produced by somatotrophs
  • common target cells are liver, skeletal muscles, cartilage and bone
  • increases cell growth and cell division by increasing their uptake of amino acids and synthesis of proteins
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9
Q

Thyroid stimulating hormone (anterior pituitary)

A
  • produced by thyrotrophs
  • TSH stimulates the synthesis and secretion of T3 and T4 from thyroid gland
  • metabolic rate stimulated
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10
Q

Follicle stimulating hormone (anterior pituitary)

A
  • gonadotrophs release FSH
  • initiates the formation of follicles within ovary
  • stimulated follicle cells to secrete estrogen
  • stimulated sperm production in testes
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11
Q

Luteinizing Hormone (anterior pituitary)

A
  • produced by gonadotrophs
  • in females LH stimulates:
    • secretion of estrogen
    • ovulation of 2nd oocyte
    • formation of corpus luteum
    • secretion of progesterone
  • in males, stimulates interstitial cells to secrete testosterone
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12
Q

Prolactin (anterior pituitary)

A
  • produced by lactotrophs
  • PRL causes milk production in women
  • function not known in males
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13
Q

Adrenocorticotrophic hormone (anterior pituitary)

A
  • ACTH produced by corticotrophs

- ACTH stimulated cells of adrenal cortex that produce glucocorticoids

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14
Q

Melanocyte stimulating hormone (anterior pituitary)

A
  • secreted by corticotrophs
  • function not certain in humans
  • increases skin pigmentation in frogs
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15
Q

Posterior pituitary (neurohypophysis)

A
  • doesn’t synthesize hormones
  • consists of axon terminals of hypothalamic neurons
  • neurons release 2 neurotransmitters that enter capillaries
    • antidiuretic hormone
    • oxytocin
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16
Q

Antidiuretic hormone (posterior pituitary)

A
  • ADH also known as vasopressin
  • response to low BP
  • decrees urine production
  • decrease sweating
  • increase BP
  • increase thirst
17
Q

Oxytocin (posterior pituitary)

A
  • 2 target tissues - both involved in neuroendocrine reflexes
  • during delivery:
    • baby’s head stretches cervix
    • hormone released enhances uterine muscle contraction
    • baby and placenta delivered
  • after delivery:
    • suckling and hearing baby’s cry stimulates milk ejection
    • hormone causes muscle contraction and milk ejection
18
Q

Thyroid gland

A
  • on each side of trachea is lobe of thyroid glands joined by isthmus
  • consists of (simple cuboidal) follicular cells surrounding follicle filled with precursor substance (thyroglobulin)… active form is T3 or T4
  • material produced and stored outside cells
  • up taken by cells and activated when needed
  • T3: triiodine hormone
  • T4: tetraiodine hormone
19
Q

Thyroid hormone functions

A
  • regulate oxygen use and metabolic rate
  • cellular metabolism increase
  • growth and development
  • controlled by pituitary
20
Q

Histology of thyroid gland

A
  • follicle: sac of stored hormone (colloid) surrounded by follicular cells that produce it
  • in between cells are called parafollicular cells
  • parafollicular cells produce calcitonin, which decreases blood calcium levels by decreasing activity of osteoclasts and excretion by kidneys
21
Q

Parathyroid glands

A
  • 4 glands
  • posterior to thyroid gland
  • principle cells produce parathyroid hormone (PTH)
  • oxyphil cell function is unknown
22
Q

Parathyroid hormone

A
  • raise blood calcium levels
  • increase activity of osteoclasts
  • increases reabsorption of calcium by kidney
  • promote formation of calcitriol (Vit D) by kidney and liver which increases absorption of calcium by intestinal tract
  • opposite function of calcitonin
23
Q

Adrenal Glands

A
  • one on top of each kidney
  • controlled by pituitary gland
  • good blood supply
  • 2 glands in 1: cortex and medulla
24
Q

Histology of adrenal gland

A
  • cortex produces 3 different types of hormones from 3 zones of cortex
    • zona glomerulosa: mineralocorticoids
    • zona fasciculata: glucocorticoids
    • zona reticularis: androgens

-medulla produces epinephrine and norepinephrine and secretes into blood

25
Q

Function of adrenal cortex

A
  • minerlocorticoids (aldosterone) secreted in response to low blood pressure, signals kidneys to absorb more sodium and water
  • glucocorticoids (cortisol) secreted in response to stress, raises blood sugar levels and also used as anti inflammatory agent (over use reduces immune response)
  • androgens have masculinizing effects (sex producing hormones)
26
Q

Function of adrenal medulla

A
  • chromatin cells receive direct innervation from sympathetic nervous system
    • develop from same tissue as postgangionic neurons
  • produces epinephrine and norepinephrine
  • hormones are sympathomimetic
    • effects mimic those of sympathetic NS
    • prepare for fight or flight
  • longer effects due to hormone in blood
27
Q

Cushing syndrome

A
  • over secretion of aldosterone

- fats destroyed and reorganized

28
Q

Anatomy of Pancreas

A
  • located in upper abdomen
  • consists of head, body, tail
  • exocrine and endocrine
  • cells (99%) in acini produce digestive enzymes (exocrine)
  • endocrine cells in pancreatic islets produce hormones: islets of langerhans
29
Q

Cell organization in pancreas

A
  • exocrine acinar cells surround a small duct
  • endocrine cells secrete near a capillary
  • lumina of acina connect together to form duct
30
Q

Cell types in pancreatic islets

A
  • alpha cells (20%) produce glucagon to increase blood sugar levels
  • beta cells (70%) produce insulin to decrease blood sugar levels
  • delta cells (5%) produce somatostatin to reduce secretions of alpha and beta cells
  • F cells produce pancreatic polypeptides to inhibit activity of exocrine part of pancreas
31
Q

Ovaries and testes

A
  • ovaries
    • estrogen, progesterone, relaxin & inhibin (under effect of FSH)
    • regulate reproductive cycle, maintain pregnancy and prepare mammary glands for lactation
  • testes
    • interstitial cells produce testosterone (under effect of LH)
    • regulate sperm production and secondary sexual characteristics
32
Q

Pineal gland

A
  • small gland attached to 3rd ventricle of brain
  • consists of pinealoctyes (secrete melatonin) and neuroglia (CT cells)
  • melatonin responsible for setting of biological clock
33
Q

Effect of light on pineal gland

A
  • melatonin secretion producing sleepiness occurs during darkness due to lack of stimulation from sympathetic ganglion (inhibits melatonin release)
  • sympathetic fibres from superior cervical ganglia terminate in pineal gland
    • inhibits melatonin release
34
Q

Thymus gland

A
  • important role in maturation of T cells in infants and children
  • hormones produced by gland promote the proliferation and maturation of T cells
    • thymosin
    • thymic humoral factor
    • thymic factor
    • thymopoietin
  • located in mediastinum in thorax

Intro Anatomy (11 decks)

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