College aantekeningen
Hormonen en homeostase deel2
- Instelling
- Universiteit Utrecht (UU)
leerstof na deeltoets 1 hormonen en homeostase
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Voorbeeld 4 van de 59 pagina's
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Voorbeeld van de inhoud
Hormonen en Homeostase 2Inhoud
Adrenals................................................................................................................................................... 1
HC 11+12 Hormones of the adrenal glands ........................................................................................ 1
Medulla............................................................................................................................................ 2
Cortex .............................................................................................................................................. 5
WC 8 .................................................................................................................................................. 12
Thyroid and parathyroid........................................................................................................................ 14
HC 13+14 Thyroid gland and parathyroid glands .............................................................................. 14
WC 9 PP ............................................................................................................................................. 25
Practicum 3 Thyroid gland ................................................................................................................. 28
Gonads and fertility ............................................................................................................................... 29
HC 15 Gonads .................................................................................................................................... 29
HC 16 Testis ....................................................................................................................................... 35
Spermatogenesis ........................................................................................................................... 35
Testis Microscopy .............................................................................................................................. 38
WC 10 Male contraception PP .......................................................................................................... 41
HC 17 Female gonads: development and function PP! ..................................................................... 44
Ovary microscopy .............................................................................................................................. 48
HC 18 Female fertility ........................................................................................................................ 50
WC 11 zie PP ...................................................................................................................................... 54
Adrenals
HC 11+12 Hormones of the adrenal glands
Adrenals on top of the kidneys, covered with fat
Endocrine gland with:
• Cortex: steroid hormone production
• Medulla: adrenalin and noradrenalin production
1
,Composed of cortex layer and medulla layer
- Cortex is a endocrine gland
o Mesoderm
- Medulla is a modified sympathetic ganglion of autonomic nervous system
o Ectoderm
Pituitary also a fusion two different tissue types
Cortex:
• Zona glomerulosa: bold cells
o Involved in regulating activity of kidney
• Zona fasciculata: oriented cell bundles
o Lipid droplets in cytoplasm
o Rich in mito’s and SER
o Free ribosomes (mostly not associated with ER)
• Zona reticularis: unoriented cells
All steroid forming cells
Medulla
• Derived from neural crest (neurale lijst)
• Surrounded by adrenal cortex
• Consists of chromaffin cells
o Affinity for potassium dichromate→ brown staining
• Innervated by cholinergic sympathetic neurons → acetylcholine as neurotransmitter
2
, - Medulla activated via ACh-releasing preganglionic sympathetic neurons, usually along with
the remainder of the sympathetic system
o Doesn’t have an exon→ adrenalin is released into blood→ to target tissue
- Neurotransmitters of sympathetic system are adrenalin and noradrenalin
- Release not in synaptic cleft but into blood→ adrenalin and noradrenalin from medulla are
hormones
All of the internal organs are innervated by the autonomic nerve system
- Connection to ganglion with many cell bodies from where peripheral cell bodies go to target
tissues
o Same organisation in adrenal medulla
Hormones formed from tyrosine:
• Catecholamines
o 90% adrenalin
o 10% noradrenalin
o Dopamine
- Half life time of 2 minutes→ short signal
• Thyroid hormones
o T4 and T3
Catecholamine functions:
• Metabolic effects: keep homeostasis upon sudden labour by mobilizing energy reserves
o Glycogenolysis→ elevate blood glucose levels
o Lipolysis→ elevate free fatty acid levels
• Cardio-vascular effects: redistribution of blood, increased blood flow and O2-supply
o Vasodilatation and vasoconstriction
➔ Important for acute stress: fright, fight and flight reaction
Sympathetic-adrenal system
• (Nor)adrenalin bind to adrenergic receptors, on smooth muscle cells in blood vessel walls
o Alpha receptors: vessel constriction (cAMP down)→ less blood to tissue
▪ Intestines (blood vessels that goes to intestine)
▪ Iris of eye→ focussing
3
, ▪ Musculi erector pilii→ makes hair rise (when cold)
o Beta receptors: vessel dilatation (cAMP up)→ more blood to tissue
▪ Skeletal muscle
▪ Lung
▪ Brain
▪ Coronary vessels but stimulates heart muscle itself→ heart rate and blood
output volume elevated
▪ Intestine→ relax muscle so that they don’t use energy
▪ Sphincters (bladder/anus)
One hormone, different receptors→ alpha on vessels to intestines, beta on vessels to muscles
➔ Tissue specific receptor expression
Metabolic effects
Adrenalin up: providing energy→ higher blood sugar levels
• Things that lower blood glucose are inhibited
• Liver takes up free fatty acids and converts it to ketone bodies→ energy
Long term energy: fatty acids
TG= triglycerides
Lipolytic hormone targets lipocytes
TG in fat droplets
- Production and storage of TG stimulated by insulin
o Counteracted by lipolytic hormones via HSL
- Adrenalin and glucagon: breakdown of TG to free fatty acids→ ketone bodies
HSL: inhibited by insulin but stimulated by adrenalin and glucagon
4
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