excretory system Flashcards
what is the purpose of the excretory system
maintaining dynamic equilibrium to keep enzymes happy,
removal of non-solid waste from the body through lungs (CO2 and H2O gas), sweat glands (in skin release: some excess h2o and salts), kidneys (filter and clean the blood to produce urine)
single cells rely on (BLANK) to remove waste
diffusion
Cluters of cells require a
transport system
is fecal matter the same as waste?
No, fecal matter was never inside your body
osmoregulation
homeostasis of the water concentration: usually measured by solute concentration
a) freshwater
- hypotonic to bodily fluids
- h2o flow into cells + salt loss- reabsorb salts
b) saltwater
- slightly hypertonic/isotonic to bodily fluids
- h2o loss from cells
c) land
- dry environment
- need to conserve water and salt
nitrogen waste
- produced naturally by amino acid breakdown
- NH3–highly soluble– highly toxic
- urea–less souble–less toxic
- ammino waste to the liver, produces urea, filtered out of the blood by kidneys, lost in urine
- uric acid- not soluble-less toxic
- crystals present in urine that can build up in joints leading to arthritis
egg laying mammals and nitrogen waste
- urine is just in the egg, needs to be converted to uric acid – insoluble (fecal matter in birds=uric acid crystal)
how is uric acid production increased
increased protein, especially meats
as the body metabolizes purine, a compound found in high-protein foods. Elevated levels of uric acid may overwhelm the kidneys’ capacity to excrete it
what is the top of kidneys protected by, and what does damage to the kidney cause
ribs, increased urine output (potential blood)
ureter
tube that drains each kidney, brings urine down to the bladder
-external
bladder
waterproof holder of urine, anything in the bladder will be sterile, stretches and changes size via stretch receptors (these receptors stretch outwards and the receptors send a message to the brain to encourage urination)
-external
urethra
- autopilot
- controllable.
-external
The urethra serves as a duct through which urine is expelled from the bladder
kidneys
bean shaped organ
- 2 layers: medulla and cortex
- filtering units: nephro
- renal artery and vein
- GOAL: to balance blood chemistry
homeostasis for the kidneys
- o2 blood flows in and out
- unfiltered blood: in through artery
- filtered blood: out through the veins
- filtered blood goes back up to the heart
- keeping the concentration of blood stable
1) pH, salinity, H2O conc, etc.
2) remove waste from blood
3) release key hormones
urine formation varies
based on diet, hydration, etc.
what do nephrons do
clean the blood and produce urine (inside of the tube represents an exterior body surface)
- nephrons are the filtering units of the kidneys
- they clean and rebalance the blood to produce urine
everything dissolved in blood plasma leaves the body through means of
- increased pressure (force “watery” components out of bloodstream into nephron)
- transports glucose, water, and ions
The 3 step-process in which nephrons clean the body
1) filtration of the blood
2) plasma leaks out through the glomerulus into the nephron in Bowmans capsule
3) h2o, na+,k+ ions, glucose, amino acids are all filtered out of the blood
- exiting of plasma via holes, thicker as it leaves the glomerulus
reabsorption of materials
- active/passive transport
- proximal tubule:
- 90% reabsorbed: glucose, ions, amino acids
loop of henle
—-descending loop of henle, lined with aquaporins (h2o moves via osmosis out of urine back into the bloodstream)
—ascending loop of henle
- no aquaporins
- lots of channels for ions: allow ions to move along concentration gradients
- most of the sodium is reabsorbed