NEURO PHYSIOLOGY Flashcards by Iman Imtiaz

what is the difference with paracrine and autocrine

paracrine is when the hormone affect local targets and autocrine is when they act on the producing cell itself

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what are the three categories of hormones

peptides and proteins eg insulin
steroid hormones which are synthesised from cholesterol
amino acid derivatives eg adrenaline and thyroid hormones

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which type of hormones need to be bound to carrier proteins and why

lipid soluble ones eg cortisol and T3,T4. the carrier proteins prevents it from degradation in the blood and it dissociates once at the receptor

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how are peptide hormones produced

produced as prohormones which have reduced activity until they’re cleaved by endopeptidases.

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where are hormones stored

in secretory granules that are released by exocytosis after the appropriate stimulus which is dependant on Ca 2+

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how are steroid hormones produced

produced from cholesterol which is stored in lipid droplets within the cell until needed. hormone synthesis takes place in the mitochondria and SER. the hormone is made and released immediately upon stimulation

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how are amino acid derivative hormones formed

the actecholines (adrenaline and noradrenaline) are synthesised from tyrosine residues and stored in secretory vesicles and rebased in response to an AP

T4 and T3 are formed by iodination of tyrosine resides and bind to intracellular receptor altering gene transcription. bind to thyroglobulin and slowly release hormones to target tissues

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what is water soluble hormone signalling

hormone binds to the cell surface receptors to activate downstream signalling eg G proteins leading to camp as a second messenger. these pathways cause changes to specific cellular reaction resulting in the response hormone. causes an enzyme cascade which happens outside as it water soluble hormones can’t cross inside and so the cascade creates a final product which can cross and will create the effect the hormone needed to create

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how does steroid hormone signalling work

the steroid hormone dissociates from carrier protein and can diffuse across the cell membrane to bind to an intracellular receptor. this complex acts as a factor which controls the expression of target genes. these pathways lead to changes in cellular reactions causing a response to the hormones

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what is the target organ and the action of ACTH

adrenal cortex and its a stress response and sodium retention

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what are the direct effects of GH

increased fatty acid use
decreased rate of glucose uptake and metabolism
glycogen breakdown

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what are the indirect effects of GH

increased formation of collagen and deposition of bone matrix

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disorders of growth hormone

hyper secretion in children results in gigantism and in adults acromegaly
hyposecretion results in pituitary dwarfism

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what hormone does the pineal gland secrete

melatonin which induces sleep and resets the pacemaker of the circadian rhythm

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how does the thyroid gland work

the stimulus causes the hypothalamus to release TRH and this causes the anterior pituitary to release TSH which causes the thyroid gland to release T3 and T4

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how does the thyroid gland release T3 and T4

thyroglobulin molecules are packaged into vesicles and exocytosed into the lumen of the follicle.
the iodide ion enters through a sodium/iodide cotransporter and exits into the lumen through a chlorine/iodide antiport
iodide ions oxidized to iodine and added to the thyroglobulin
MIT, DIT, T3 and T4 mixture is formed
the mixture is endocytosed back into the follicle
the mixture undergoes proteolysis and the T3 and T4 is released

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what is the function of T3

increases basal metabolic rate
maintain body temp
stimulate protein synthesis

it has a greater activity than T4

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what is the function of the parathyroid hormone

involved in calcium homeostasis. Sustained levels of PTH acts to increase osteoclast activity and bone resorption, releasing calcium

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what does PH do to kidney

increase reabsorption of calcium from urine
increases the expression of the enzyme which activates vitamin D
increases the excretion of phosphate

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what is the function of vitamin D metabolite

increases the absorption of calcium and phosphate in the GI tract

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what hormone does the zona glomerulosa produce

mineralcotricoid

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what hormone does the zona fasiculata produce

glucocorticoids

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what hormone does zona reticularis produce

adrenogens

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what hormone does the medulla produce

catecholamine, noradrenaline and ardrenaline

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what is the function of aldosterone

increases sodium and water reabsorption in the kidney

what is the function of androgens

source of testosterone in women

what is the function of cortisol

exerts anti-inflammatory effects and decreases immune response

what are disorders of the adrenal gland

excessive cortisol leads to Cushing syndrome

what is up regulation and down regulation

upregulation is when there is an increase in the number of receptors on the membrane and downregualtion is when there is a decrease in the number of receptors on the membrane

what is hormone deficiency

often due to autoimmune destruction of the endocrine gland

what is hormone resistance

mutation in hormone receptors which leads to downstream effects

what is hormone excess

endocrine tumors antibody mediated trigger of hormone receptors

what is the function of insulin

increase glucose absorption from the blood and stimulates glycogen formation

what is the function of glucagon

stimulates glycogenolysis and inhibits insulin release

which cells in the islets of langerhan produce insulin and which ones produce glucagon

insulin- beta cells | glucagon beta cells

where are the alpha cells located compared to beta cells

alpha cells line the centre and beta cells surround it

what is the normal blood glucose level

4-6mmol/L

how does glucose enter the cell

needs a glucose transporter which is the GLUT-2 transporter in beta cells

how is insulin released

glucose enters beta cell and is metabolized. this leads to an increase in ATP. The potassium channel gets inhibited and this leads to depolarization and so Ca2+ enters and this leads to insulin secretion

what are incretins

peptide hormone released by the intestine that act on pancreatic cells to stimulate insulin release

what is the effect of insulin on target cells

insulin receptor is tyrosine-kinase linked and when insulin binds it leads to vesicles containing GLUT-4 to move to the membrane which increases transcription of glucose metabolism enzymes. this surpasses gluconeogenesis and increases potassium uptake

what is the HbA1c test

older Hb binds to glucose and becomes glycated. an increase in blood glucose means increase in HbA1c and is used to indicate levels over three months

what are the general effects of high blood glucose

increased thirst | increased appetite frequent urination

what are the acute complications of high blood glucose

diabetic ketoacidosis blurred vision low consciousness coma/death

what are the long-term complications of high blood glucose

nerve damage sigh loss CV disease

what is type 1 diabetes | T1DM

autoimmune | pancreas doesn't produce insulin

which group is most likely at risk of T1DM and what is the genetic susceptibility

north europeans 30% more likely if parents have it

what is type 2 diabetes T2DM

insulin resistance

which group is most likely at risk of T2DM and what is the genetic susceptibility

black African and carribean and south asians 75% more likely if relative has it

what factors cause T2DM

insulin resistance causes more glycogen to be broken down and increased blood glucose levels insulin resistance also causes less glucose uptake from blood

what are the treatments for diabetes

T1DM-diet and exercise and insulin T2DM-diet and exercise and drugs e.g. metformin

what is double diabetes and how is it caused

when someone has type 1 and they get onto insulin which causes weight gain this then can lead to insulin resistance which is type 2

what is gestational diabetes

high blood glucose without type 1 or type 2 but is cause by insulin resistance 3-9% of preganancies

what are the risks to a child when the mother has gestational diabetes

``` oversize newborn low on sugar jaundice higher risk of obesity x6 of getting T2DM ```

what is the link between Alzheimers and diabetes

an increased risk of AD with diabetes. insulin resistance lowers energy of metabolism and so increases stress on brain cells which can lead to AD

what are some complications of diabetes

frequent urination due to increased osmotic pressure in blood increase in thirst (polydipsia)

what is diabetic neuropathy

-nerve damage due to damage to small blood vessels and toxins

what is diabetic ketoacidosis

cells are unable to transport glucose and so consume fats for energy fats breakdown to produce acidic ketones which leads to low pH

what are symptoms of ketoacidosis

``` muscle pain heart palpitations nausea vomiting coma death ```

what is hypoglycaemia

low blood glucose which leads to inability to provide energy to neurons

what are symptoms of hypoglycemia

``` headache dizziness blurred vision hunger tachycarida shaking ```