excretion Flashcards
excretion
the removal of metabolic wastes from the body
metabolism
the sum total of chemical reactions that occur in a cell
what waste products are formed during metabolism ?
- excess water
- CO2
- nitrogenous wastes (urea ,uric acid)
origin of CO2
it is formed as a by-product of cellular respiration
origin of excess water
formed as a by-product of cellular respiration and from the intake of fluid and food
origin of urea
formed in the liver from the deamination of excess amino acids
origin of bile pigments
formed in the liver during the breakdown of haemoglobin
origin of uric acid
the end product of metabolism of nucleic acids
blood vessels connected to the kidney
aorta-carries oxygenated blood ,food and waste products from the heart
renal artery - carries blood from the aorta to supply the kidneys with oxygen and food and it brings the waste products to the kidney to be excreted
inferior vena cava-carries deoxygenated blood and other substances from the kidneys back to the heart
renal vein -carries deoxygenated blood ,purified of metabolic waste from the kidneys into the inferior vena cava
bladder
stores the urine
kidney
a excretory organ that filters nitrogenous waste out of the blood and produces urine
ureter
carries urine to the bladder
urethra
carries urine out of the body
what occurs in the hilum
the renal artery that enters the kidney ,the renal vein and ureter that exits the kidney
connective tissue membrane that surrounds the kidney
renal capsule
reddish brown region directly under the renal capsule
cortex
that inner region of the kidney, which is lighter in color and contains tubes which are arranged in groups
medulla
nephron
structural and functional units of the kidney , which is made up of 2 parts: malpighian body and renal tubule
malpighian body
found on the end of the nephron in the cortex ,
what is found in the malpighian body
a double-walled ,cup shaped structure called the bowmans capsule and inside the bowmans capsule is a capillary network of blood vessels called the glomerulus .
blood vessels that transport blood TO THE GLOMERULUS
Afferent arteriole
blood vessel that transports blood AWAY FROM the glomerulus
Efferent arteriole
cells with projections between in which small openings , filtration slits occur
podocytes
the cavity between the inner and outer wall of the bowmans capsule
cavity of the bowmans capsule
what is in the renal tubule
- the proximal convoluted tubule (found in the cortex )
- the loop of henle( found in the medulla )
- the distil convoluted tubule (found in the cortex)
why does the glomerular filtration occur in the malpighian bodies
the diameter of the afferent arteriole is larger than that of the efferent arteriole ,therefore the blood in the glomerulus is under high pressure and this allows for ultrafiltration
how is the ultrafine filter formed and what is filtered through it ?
the thin endotheluim with pores lining the blood capillaries of the glomerulus together with the podocyte layer with filtration slits of the bowmans capsule form the ultrafine filter and filtrable parts of the blood are filtered through .
what promotes the filtration process
- high blood pressure in the glomerulus
- large filtration surface
- parmeability of the glomerular membrane
explain glomerular filtration
glomerular filtration occurs in the malpighian bodies because the diameter of the afferent arteriole is larger than that of the efferent arteriole ,so the blood in the glomerulus is under high pressure this allows for ultrafiltration. the thin endothelium layer with pores lining the the blood capillaries of the glomerulus and the podocyte layer with filtration slits of the bowmans capsule form the ultrafine filter which filters the filtrable parts of the blood , the blood cells and the plasma proteins are too large to be filtered so they remain in the blood capillaries .The the part of the blood that moves into the bowmans capsule is known as the glomerular filtrate which carries the useful substances and the waste products
what is the part of the blood that moves into the bowmans capsule and contains useful substances and waste products
glomerular filtrate
tubular reabsorption
the useful substances, which passed the glomerular membrane , need to be reabsorbed and returned back to the bloodstream, this is so that the useful substances dont form part of the urine and be excreted . the filtrate leaves the bowmans capsule and enter the proximal convoluted tubule
how is the malpighian body adapted for filtration ?
- the afferent arteriole is wider than the efferent arteriole , which causes a high blood pressure in the glomerulus that promotes filtration
- the bowmans capsule is cup-shaped which provides a large surface for filtration
- the capillary network of the glomerulus has a large surface area, which increases the efficiency of filtration
- podocytes have filtration slits that only allow smaller parts of the blood to filter through
adaptions of the proximal convoluted tubule for reabsorption
- the tube is long and convoluted which enlarges the surface for maximal absorption
- the peritubular capillary network surrounds the renal tubule so that the reabsorbed substances can easily move into the bloodstream
- the cuboidal epithelial cells which line the tubule have many mitochondria to provide energy for active transport
- the cuboidal epithelial cells have finger-like projections that increase the absorption surface.
excretion of urine
the liquid entering the collecting duct is now called urine.( the urine of a healthy person has only water ,salts and wastes)
urine from 2 million nephrons pass through the collecting duct into the renal pelvis
the urine moves down the ureter into the bladder where it is stored and is then released through the urethra
tubular excretion
waste products, uric acid ,creatinine as well as hydrogen and ammonium ions that are in the blood that could not filter through the bowmans capsule are excreted by active transport into the distal tubule
adrenal gland
secretes the hormone aldosterone which travels to the kidneys and helps to control the balance of salts in the blood ,thus controlling blood pressure
aldosterone
hormone secreted by the adrenal gland
use of aldosterone
helps control the balance of the salts of the blood thus controlling the blood pressure
secretion
the release of useful substances that are produces by cells for important functions
blood supply to the kidneys
- the renal artery is a branch of the the aorta that the supplies the kidneys with oxygenated blood rich in metabolic waste products
- the renal artery enters the kidney through the hilum , the artery branches into smaller arteries .these arteries extend between the pyramids in the direction of the cortex .
- they branch further until they form smaller branches called afferent arterioles
- one afferent arteriole extends to each bowmans capsule
- the afferent arteriole divides to form a capillary network called the glomerulus ,in the bowmans capsule
- the the blood capillaries then merge to form a effernt arteriole that transports blood away from the bowmans capsule .
- the efferent arteriole then branches again to form a peritubular capillary network ,which surrounds the renal tubule
- the peritubular capillaries combine to form venules then larger veins and eventually form the renal vein .
- The renal vein takes deoxygenated blood without waste products from the kidney to the heart via the inferior vena cava
