Urinary system!

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  • Created by: Izzy2807
  • Created on: 17-02-20 16:36
What is dehydration?
A state of relative deficiency of fluid that causes adverse effects on function/clinical outcome
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What are the fluid gains and losses?
Gains: drinking, food and metabolism. Losses: urine, sweat, faeces and lungs
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Where is the fluid in the body?
Extracellular: circulating blood (20%) and interstitial fluid (80%) (15l). Intracellular fluid (25l)
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What variables impact fluid in the body?
Age and sex, muscle comp. MUSCLE HAS MORE WATER, FAT LESS
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What is the main cation in extracellular fluid?
Sodium. Lot's of potassium in intraceullar fluid, less K
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What are the functions of water?
Transportation of dissolved nutrients, hormones, enzymes, blood platelets, RBCs and WBCs. MEDIUM FOR METABOLSM. solvent for electrolytes, heat dist, dig/exc, lubrication!
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What does Na and K do?
Na: osmosis regulation. K: Active transport (resting potential, nerves!)
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What does Cl and Ca do?
Cl: osmosis (balances Na) and pH. Ca: salts for bones, teeth, intracell. communication, clotting, NT release
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What does phosphate and Hydrogen to?
P: bone, teeth, ATP and pH buffer. H: pH (more H, more acidic)
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What does bicarbonate do (HCO)?
buffers pH, released in response to secretin
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What governs fluid movement and what is osmolality?
Osmotic pressure (WP) governs fluid movement. Osmolality is the concentration of dissolves solvents/per litre.
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What is tonicity?
A solution's osmotic pressure (pressure gradient based on concentration)
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What are the constituents of plasma?
92% water, 8% proteins, ions, dissolved gases, hormones, nutrient molecules and wastes!
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What governs plasma fluid movement?
Blood pressure, filtration and viscousity
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What governs intercellular fluid (interstitial fluid) movement?
Oedema and turgur
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What governs intracellular fluid movement?
Osmosis and metabolism
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What effect does hypervolemia (too much water) have on osmolality?
Lowers osmolality (higher water potential)
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What is the function of the kidneys?
Regulate urine production and urine concentration (maintains fluid homeostasis), helps maintain BP and excrete toxins
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What is the function of the ureters and bladder?
Ureters: transfers urine from the kidneys to the bladder via peristaltic waves. Bladder: muscular and distensible, stores urine
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What is the function of the urethra?
Opening for secretion of urine, connects to bladder via urethral bladder sphincter
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What is the function unit of the kidney called?
The nephron
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What are the 4 main steps in urine production?
1) ultrafiltration 2) reabsorption 3) secretion 4) selective reabsorption
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What is the renal corpuscle?
Consists of bowman's capsule and glomerulus (bundle of capillaries).
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What are the 3 filtration layers in the renal corpuscle?
Endothelial cells of the glomerulus, basement membrane and podocytes. Small, negatively charged particles
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What factors determine the Glomerular Filtration Rate?
BP (cons/dil of arterioles), hydrostatic pressure (con of LV and bottle-neck afferent/efferent arteriole) and osmotic pressure (opposing forces)
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What molecules can and can't pass through the glomerulus?
ALL molecules (glucose, AAs, urea etc. and plasma) apart from large proteins
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What molecules are reabsorbed back into the blood by the PCT?
All glucose and AAs, 60-80% of water, most Na, Cl and K (Na creates gradient, Cl follows). Urea, creatine, nitrogenous molcules move INTO PCT
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What happens at the loop of Henle? (concentrating urine)
Descending limb more permeable to loss of water, osmolarity increases as we move down the medulla (more fluid out), ascending limb - more permeable to loss of Na and Cl
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What happens at the DCT/CD? (selective reabsorption)
Na, Cl, Carbonate and water OUT...K, ammonium, urea IN.
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What 3 hormones regulated reabsorption in the DCT/CD?
Aldosterone (Na and K out), Parathyroid Hormone for Ca out, ADH for water out
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What happens during secretion (DCT/CD)?
K, H, ammonium, creatinine, urea move from capillaries to filtrate (against diff gradient, AT)
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How do the kidneys regulate acid base?
Too acidic? Kidneys can reabsorb more HCO and secrete more Hydrogen
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What 2 factors does urine concentration depend on?
Medullary osmotic gradient (LoH...more water out of descending limb and into blood) and ADH (more water out of CD)
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How does aldosterone work?
Increase in K/decrease in Na, a, osmoreceptors, renal cortex releases aldosterone, acts on kidney tubules to increase Na reabsorption into blood (therefore less water in kidneys)
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How does the Renin-Angiotensin system work?
Decrease in BP/BV, kidney baroreceptors detect, kidney releases renin. Renin converts AT to AT1. ACE turns AT1 to AT2 - vasocontricts arterioles (increase PR and BP). AT2 stimulates adrenal cortex to release aldosterone (increase water in blood, BV)
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How does ADH regulate fluid?
Lowered WP, osmoreceptors in Hyp, more impulses to Post.Pit.Gland, ADH released...increased permeability of CD to loss of water, increased WP, BV and increase urine concentration
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What are the normal constituents of urine?
90-95% water, 10-5% inorganic/organic compounds (urea, ammonium, creatinine)
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What is anuria, oliguria, polyuria and dysuria?
Anuria: no urine. Oliguria: small amount of urine. Polyuria: too much urine (large). Dysuria: painful/difficulty in passing urine
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What does Atrial Natriuretic Peptide hormone do?
Binds to receptors in kidneys, promotes salt excretion, more water moves out of kidneys (into interstitial fluid) so lowers BP/BV, water out of blood...
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What centre regulates micturation (weeing!)?
Pontine centre (hypothalamus and cerebral cortex - pontine centre - lumbar and sacral spinal chord)
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How does the bladder fill/store urine?
SYMPATHETIC motor nerves stimulates and pudendal nerves (somatic)- detursor muscle relaxes, internal sphincter closed, external sphincter contracting
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How do you urinate? (bladder stretch receptors stimulated)
Sensory nerve impulses increase to PONS, symp. nerves inhibited, parasymp nerves stimulated: detursor muscle contracts, internal sphincter opens, external sphincter relaxes
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What are the signs of dehydration?
Thirst, dry mucus membranes, darker (more concentrated urine), reduced skin elasticity, reduced capillary refill time, hypotension, lowered pulse, BP and resp.
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Other cards in this set

Card 2

Front

What are the fluid gains and losses?

Back

Gains: drinking, food and metabolism. Losses: urine, sweat, faeces and lungs

Card 3

Front

Where is the fluid in the body?

Back

Preview of the front of card 3

Card 4

Front

What variables impact fluid in the body?

Back

Preview of the front of card 4

Card 5

Front

What is the main cation in extracellular fluid?

Back

Preview of the front of card 5
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