Excretion Flashcards
What is deanimation
Removal of an amino group on an amino acid
What does deanimation produce
Ammonia
What is ammonia converted into
Urea
Excretion definition
Process that rids the body of metabolic wastes (especially nitrogenous wastes)
Kidney function in excretion
Excretes nitrogenous wastes
Liver function in excretion
Excretes bile pigments
Lung function in excretion
Excretes Co2
Skin functions in excretion
Excretes sweat
What is defecation
Process that rids body of undigested and unabsorbed food remains
What is the pathway of urin
Kidney to ureters to bladder to urethra and then exits body
Formula of ammonia
NH3
Why is ammonia converted to urea in the liver
It is very toxic to land mammals
What substances are excreted besides nitrogenous wastes
-HCO3- (bicarbonate)
-Salts
-Water
-Urochrome
What is urochrome made from
The break down of heme
What does urochrome do in urine
Gives it its yellow color
What is urine composed of
3% urea, 2% salts, and 95% H2O
What is the Renal Vein
Vein that carries deoxygenated blood from kidneys back to heart
What is the renal artery
Artery that carries oxygenated blood to the kidneys
What is the ureter
Muscular tubes that move urine from kidney to bladder by peristalsis
What is the bladder
A place that urine is stored before removed from body
How much urine does the bladder hold
600-1000mL
How does the bladder notify when its full
It has stretch receptors to indicate the brain when its full
What is the urethra
A tube connecting the bladder to the outside
How long is the urethra
6 inches in a man, less than 1 inch in a woman
Why do women get more infections in the urethra
It is shorter than a man
What are the kidneys function
To excrete urine, regulate blood volume and PH
How much blood does the kidney filter
1200L/daily
How does the kidney regulate blood volume and osmotic balance
It excretes or conserves water
How does the kidney regulate ion concentration
It controls the excretion of salts (mostly Na+)
How does the kidney regulate blood PH
Excretes excess acids or base
What does the kidney excrete if blood is too acidic/basic
Acidic: H+ is excreted and HCO3- is reabsorbed
Basic: H+ not excreted and HCO3- not reabsorbed
What toxic by-products does the kidney excrete
Urea, ammonia, uric acid and creatinine
What are the 3 main parts of the kidney
renal cortex, renal medula, renal pelvis
What is the renal medula responsible for
Water reabsorption and salt balance
What is the renal pelvis responsible for
Collecting urine from tubules and directing it into the ureter
What is the renal cortex responsible for
Making urine and many other things
What are the functional units of the kidney
Nephrons
What do nephrons do
Produce urine and filter wastes from the blood and retain water/other needed materials
How many nephron per kidney
1 million
What is the bowmans capsule
A cuplike end of a nephron where wastes are forced out of the blood and into the nephron
What is the afferent arteriole
An arteriole that carries blood to the glomerulus
What is the efferent arteriole
An arteriole that carries blood from the glomerulus
Pathway of blood in the kidney
Renal artery, afferent arteriole, glomerulus, efferent arteriole, capillary network, venule, Renal Vein
What are the steps of urine formation
Pressure filtration, selective reabsorption, urine concentration, tubular excretion
What is pressure filtration
Where high blood pressure in the glomerulus forces small molecules into the bowmans capsule.
What happens to molecules forced into the bowmans capsule
The form filtrate
What is necessary for filtration
High blood pressure
Why is the afferent arteriole wider than the efferent
So that the blood in the glomerulus is under high blood pressure going into the efferent arteriole
Where do molecules that are selectively reabsorbed go to
The proximal convoluted tubule to the peritubular capillary network. (Back into the blood)
What gets selectively reabsorbed
Most h2o, nutrients, some salts
What doesnt get reabsorbed
Some h2o, wastes, excess salts
What is selective reabsorption
A very selective process where useful filtered materials are retuned to the pertibular capillary netweok both actively and passively
Where does water reabsorption mainly occur
At the loop of henle and the collecting duct
What does active reabsorption of salt at the loop of henle result in
The passive transport of water at both the loop of henle and collecting duct
Thus urine concentration
What is tubular excretion/secretion
An active process where other non-filterable wastes are added to the tubular fluid so they are excreted in urine aswell
Where does tubular excretion occur
In the distal convoluted tube
What is secreted in tubular excretion
Penicillin, histamine, H+ ions, NH3
What hormones help the kidneys regulate the volume of blood
ADH (antidiuretic Hormone)
Aldosterone
What is ADH released by
Pituitary gland
What does ADH do
Promotes reabsorption of water from collecting duct and distal convoluted tube
How does ADH work
- Cells in the hypothalamus detect low H2O in blood
2.ADH made in the hypothalamus is released into blood (distal convoluted tubule and collecting duct) - More H2O is reabsorbed and volume of urine decreases
- Therefore blood volume increases
What inhibits ADH
Diuretic drugs and alchohol
Where is aldosterone released
Adrenal cortex (adrenal gland is atop kidneys)
What does aldosterone do
Acts on kidney to retain Na+ and excrete K+
What happens if Na in blood is too low
Hypotension (low blood pressure)
What happens if Na in blood is too high
Hypertension (high blood pressure)
