31 Excretory Flashcards
Kidneys location and links
Lie at the back of the abdominal cavity. Each kidney is connected to a structure called the ureter. It is responsible for carrying the urine back to the urinary bladder. Sphincter muscles regulate micturition.
The kidneys receive blood from the
Renal artery and blood leaves through renal vein
The urinary system general function
Removes toxic by products of metabolism from the bloodstream, thus the kidneys are essential. Salts, glucose, proteins, ions, and water must be conserved or reabsorbed back into the body.
Glomerular filtrate
Preurine. Contains urea, aa, water, salts, glucose, and ions.
It contains the same substances as blood plasma, except larger proteins.
What many L of urine are produced each day?
1.5L
Kidney hormones
EPO (erythropoietin): stims RBC production
Renin: Regs BP
All the blood in our body passes through the kidneys every _ minutes
5
Functional unit of kidneys
Nephron, each kidney contains about 1 mil.
Each nephron originates in the cortex.
Filtration path
Glomerulus -> Bowman’s Capsule -> Proximal T -> Loop of Henle -> Distance T - > Collecting Duct - > Renal Pelvis - > Ureter
Afferent arterioles
Supply blood to the glomerulus. Efferent arterioles path to leave for blood.
Excretory System 4 processes micuriation
1) Filtration - Glom, BC
2) Reabsorption - PCT
3) Secretion- DCT
4) Excretion
Hydrostatic pressure(BP) drives filtration in the glomerulus. Ions, glucose, aa, small solutes, Urea, Vitamins, is filtered
Glomerulus
Large surface area due to great number of capillaries. These capillary walls are more permeable that most capillaries to H20, small solutes, ions.
Large molecules are held back and put back into blood. Then proceeds to glomerular filtration.
Bowman’s capsule cells
Podocytes involved with filtering. Podocytes have long tentacle like extensions.
Proximal Convoluted T
PCT- most reabsorption takes place here, packed with mitochodria. 75% of Na+ goes out by active transport by ATPase pump, CL- follows through charge attraction, and H2O goes by osmosis.
Glucose, aa, drugs, nutrients, and other ions are transported out of the PCT by active transport to the interstitial fluid and to the peritubluar capillaries.
Reabsorb 65% of H2O, all small plasma proteins and vitamins.
H+ + NH3 -> NH4+.
Urea is only partly reabsorbed, but at a slower rate than H3O+.
Loop of Henle
Descending : Aquaporins are very permeable to water. Low salt permeability, as filtrate descends the loop, urine becomes more concentrated.
Ascending : NaCl moves outward, but no H2O moves since here is impermeable to H2O. The fluid goes hypertonic in the descending limb to hypotonic in the ascending limb.
Distal convoluted tubule
The fluid is hypoomsotic compared to normal body fluid. K+, H+, and NH4+ are secreted. Which also helps reg the pH. Many mitochondria but not as much as PCT.
Aldosterone ions
Rate of Na+ absorption and K secretion by Na+ pumps are reg’d.
Juxtaglomerular apparatus
Involved with regulating blood pressure and filtration rate of the glomerulus. If BP drops, the blood volume drops. Some juxtaglomerular cells produce renin (myoendocrine cells).
Renin
converts angiotensinogen to angiotensin I. I goes to II. Angiotension II constricts blood vessels, increasing BP. Angiotension II also stim. increased aldosterone secretion, allowing more Na+ and H2O reabsorption.
Macula Densa
Senses changes in Na+, relays info to the juxtaglomerular apparatus to release Renin.
Collecting duct
When the kidneys need to conserve more water, water can move out by osmosis concentrating the solutes including urea left in the filtrate. In the presence of ADH, water can leave the collecting ducts and be conserved for use. Urine becomes hypertonic in the presence of ADH.
Alcohol and ADH levels
Alcohol decreases the ADH levels, water is not returned but you end up urinating more.
ADH
Regs water balance. Increases the permeability of collecting duct to water and some urea. Gives more conc. urine and reduced water loss from the body.
After collecting ducts urine goes
to the Renal pelvis through the ureter to the Urinary bladder, Urethra.
Desert animals and water
Those animals eats dry seeds high in carbohydrates and low in protein. Oxidation of fatty seeds produces metabolic water.
Long loops of Henle are displayed. The longer the loop, the more urine can be concentrated. Most of the water is reabsorbed.
Diuretic makes you increase urination by
a) Decreasing permeability of collecting ducts
b) Decreasing ADH production
Coffee, tea, and alcohol are all diuretics.
Urine composition
95% water, Urea (aa), uric acid (nucleic acid metabolism), creatine (metaboilsm of creatine)
Rate of glomerular filtration is directly proportional to
Filtration pressure
Afferent arteriole is under which NS control?
Sympathetic NS. If the afferent arteriole becomes constricted:
a) Glomerular hydrostatic pressure decreases
b) Filtration rate decreases
c) Volume of urine flow decreases thus urine output decreases
Efferent arteriole is constricted blood cannot flow out
Glomerulus is backe up.
a) Glomerular hydrostatic pressure now increases
b) Filtration rate increase
c) Urine output increases
d) Potential urine output increases
As the bladder fills with urine, stretch receptors are stim.
And the need to urinate occurs. The micturition reflex center is located in the spinal cord.
Counter current mechanism
Recycling of NaCl that permits the kidney to maintain a salty environment in the interstitial fluid at the bottom of the loop of Henle. The Na+ and Cl- ions from the ascending loop return to the descending loop.
Malphigian tubulue
Main excretory structure of insects.
Uric acid other species
Birds, Reptiles, Insects, and land snails
Mammals and mature amphibians nitrogenous wastes
Urea
Aquatic animals nitrogenous waste
ammonia
Uric acid compared to ammonia or urea
Uric acid is water soluble and less toxic. Uric acid is in the form of crystals.
Contractile vacuoles
Organelle used for osmoregulation and waste removal.
Paramecium, amoeba, some algae, some fungi, and hydra.
Flame cells
Function like a kidney, waste removal.
Excretory cells in flatworms (platyhelminthes) and rotifers.
Freshwater fish
Large amounts of urine are made and urine is less conc that fluids of the body. Dilute urine
Marine Fish
Small amount of urine, urine fairly conc.
UTI in female more common
Urethra is shorter in females than males.
Painful urination, burning sensation, feeling urge to urinate but cannot, malaise. Cloudy dark urine which smells bad and might contain blood.
