Chapter 11 - Excretion Flashcards
excretion - definition
removal of metabolic wastes produced in the body
elimination - definition
removal of indigestible material
most of the body’s activities produce metabolic wastes that must be
removed
aerobic respiration leads to production of
CO2 and H2O
deamination of amino acids in the liver leads to production of
nitrogenous wastes - urea; ammonia
all metabolic processes lead to production of
mineral salts
mineral salts produced by all metabolic processes must be excreted by the
kidneys
in phyla: protozoa, cnidarians - all cells are in contact with
external, aqueous environment
water soluble waste (ammonia; CO2) can exit cell via
simple diffusion through cell membrane
passive excretion
water solube wastes exiting cell via simple diffusion
contractile vacuole
some freshwater protozoa
organelle specialized for water excretion by active transport
cell is able to maintain volume and pressure by
excess water, which continually diffuses into the cell from hypotonic environment (fresh water) is collected and periodically pumped out of cell
in annelids (earthworms), carbon dioxide excretion occurs directly through
moist skin
nephridia
two pairs in each body segment;
excrete water, mineral salts, nitrogenous wastes in form of urea
insects (arthropods) - carbon dioxide is released from _____ into ______
tissue; adjacent tube-like trachaea
tube-like trachaea of insects are continuous with external air through openings called
spiracles
nitrogenous waste excreted in form of
solid uric acid crystals
the use of solid nitrogenous wastes is an adaptation for the
conservation of water
mineral salts and uric acid accumulate in the
malphigian tubules
after accumulating in the malphigian tubules, mineral salts and uric acid are transported to the
intestine
once transported to the intestine, the mineral salts and uric acid are
expelled with solid wastes of digestion
principal organs of excretion in humans
lungs, liver, skin, kidneys
excretion in the lungs
CO2 and water vapor diffuse from blood and are continually exhaled
excretion in skin
sweat glands excrete:
water
dissolved salts
small quantity of urea
perspiration serves to regulate
body temperature
evaporation of sweat produces
cooling
liver and excretion
processes:
nitrogenous wastes
blood pigment wastes
other chemicals for excretion
urea is produced by
deamination of amino acids in the liver
once urea is produced, it diffuses into the
blood for excretion in kidneys
bile salts and red blood pigments are excreted as ____ and pass out with the _____
bile; feces
kidneys function to maintain
osmolarity of the blood
in addition to maintaining osmolarity of the blood, kidneys function to
excrete waste products and toxic chemicals
conserve glucose, salt and water
the kidneys regulate the concentration of
salt and water in the blood
the kidneys regulate concentration of salt and water in the blood through
formation and excretion of urine
the kidneys are shaped like
beans
the kidneys are located
behind the stomach and liver
each kidney is composed of
~1 million units of nephrons
the kidney is divided into ____ regions
3
the regions of the kidney
outer cortex
inner medulla
renal pelvis
nephron - structure
Bowman's capsule glomerulus proximal convoluted tubule loop of Henle distal convoluted tubule collecting duct
Bowman’s capsule
bulb
embraces capillary bed - glomerulus
glomerulus
capillary bed
Bowman’s capsule leads into a
long coiled tubule
long coiled tubule following Bowman’s capsule is divided into
4 functionally distinct units
4 functionally distinct units following Bowman’s capsule
proximal convoluted tubule
loop of Henle
distal convoluted tubule
collecting duct
loop of Henle runs through
medulla
convoluted tubules and bowman’s capsule are in the
cortex
the collecting tubules serve to transport
concentrated urine
from the collecting tubules, the concentrated urine flows into the
pelvis of the kidney
pelvis of the kidney
structure, location
funnel-like region
opens directly into ureter
ureter from each kidney empty into the
urinary bladder
urinary bladder
where urine collects until expelled via the urethra
urine is expelled via the
urethra
most of the nephron is surrounded by a complex
peritubular capillary network
peritubular capillary network
surrounds nephron facilitates reabsorption of: amino acids glucose salts water
three processes that lead to urine formation
filtration
secretion
reabsorption
blood pressure forces 20% of the blood plasma entering the glomerulus through the
capillary walls and into the surrounding Bowmans capsule
filtrate
fluid and small solutes entering the nephron
the filtrate is _____ with the blood plasma
isotonic
particles too large to filter through the glomerulus,
e.g. blood cells
albumin
remain in the circulatory system
filtration is a ____ process
passive
filtration is driven by the
hydrostatic pressure of the blood
the nephron secretes
acids
bases
ions (potassium, phosphate)
nephron secretes substances from the _____ into the _____
interestitial fluid;
filtrate
nephron secretes substances from the interstitial fluid into the filtrate via ____ and _____ transport
active and passive
materials are secreted from the _____ into the ____
peritubular capillaries;
nephron tubule
essential substances examples
glucose
salts
amino acids
essential substances and water are _____ from the filtrate and _____
reabsorbed;
returned to the blood
reabsorption occurs in the
proximal convoluted tubule
reabsorption is an _____ process
active
movement of molecules is accompanied by the
passive movement of water
movement of the molecules accompanied by the passive movement of water results in the formation of
concentrated urine
concentrated urine is _____ to the bood
hypertonic
glomerulus is like a collander
small molecules dissolved in the fluid will pass through the glomerulus (e.g. glucose which is later reabsorbed)
large molecules (e.g. proteins and blood cells) will not
if blood cells or protein are found in the urine, this is indicates a problem with
levels of glomerulus
nephron - function
maintains bloodstream’s solute gradient
through selective permeability of its walls and the maintenance of an osmolarity gradient, the nephron
reabsorbs nutrients, salts, water from filtrate and returns them to body
the selective permeability of the tubules establishes an ______ in the ______
osmolarity gradient;
interstitial fluid
by exiting and reentering at different segments of the nephron, solutes create an
osmolarity gradient
tissue osmolarity increases from _____ to _____
cortex;
inner medulla
solutes that contribute to maintenance of osmolarity gradient
urea
salt (Na+ and Cl-)
the osmolarity of urine is determined by
the concentration of dissolved particles
the osmolarity of urine is established in the
collecting tubule by means of counter-current-multiplier system
counter-current-multiplier system
anatomic arrangement of the loop of Henle within the kidney permits establishment of the concentration gradient that permits the reabsorption of 99% of filtrate in the collecting tubules
the anatomic arrangement of the loop of Henle within the kidney permits
concentration gradient
the concentration gradient permits
the reabsorption of 99% of the filtrate in the collecting tubules
reabsorption of 99% of the filtrate occurs in the
collecting tubules
the production of concentrated urine is made possible by
counter-current-multiplier system
the counter-current system causes the medium in the medulla of the kidney to be
hyperosmolar
the medium in the medulla is hyperosmolar with regards to the
dilute filtrate flowing in the collecting tubule
as filtrate flowing in the collecting tubules passes through this region of the kidney, on its way to pelvis and ureter,
water flows out of hte collecting tubules by osmosis
water flows out of the collecting tubules by
osmosis
water is removed by
capillaries flowing in the medulla
reabsorption of water in this zone of the kidney (medulla) depends on the
permeability of the collecting tubules of water
the reabsorption of water in the kidney permits
concentration of urine
regulation of the permeability of the collecting tubule to water is by
ADH (vasopressin)
ADH _____ permeability of the collecting duct to ______
increases;
water
ADH increase permeability of collecting duct to water allows
more water to be absorbed and more concentrated urine to be formed
