EXCRETORY SYSTEM Flashcards
(20 cards)
Excretion
Removal of wastes of metabolism from the body
Organs
Lungs
sweat glands
Kidney
Liver
The liver
- the liver is located in the upper abdominal cavity.
hosts different functions such as:
1. detoxifies alcohol and some drugs such as antibiotics
- prepares material for excretion
- deactivates hormones and converts them into a form that can be excreted by the kidneys
- Breaks down haemoglobin from red bloods cells to produce bile pigments, which are then passed out with faeces.
Dimination
Removal of amino group (NH2) from the amino acids, to break down proteins for energy.
Equation:
Amino acids + oxygen ➡️ carbohydrates + ammonia
Ammonia + carbon dioxide ➡️ urea + water
The skin layers
Top
Epidermis
⬇️
Dermis
⬇️
Innermost skin layer
pores
sweat glands
hair follicles
nerves
The skin
Main function of the skin, is to provide a protective covering over the surface of the body and to regulate body temperatures.
The skin secrete sweat through sweat glands.
sweat contains, urea, lactic acid, water, sodium chloride and some drugs (salicylic acid).
sweat glands are located in the lower layers of the skin.
duct carries the sweat to the skins surface where it opens at a pore
cells surrounding the glands are able to contracts squeezing the sweat through the skins surface.
Kidneys
Pairs of reddish- brown organs.
Approx. 11cm long.
kidneys, bladder and associated duct make up the urinary system.
primary role is to filter wastes and excess fluid from blood, producing urine.
Kidney strucutre
Kidneys are surrounded by a - capsule
outer layer - cortex
inner layer - medulla
medulla consists of - pyramids
pyramids are separated by - columns
moves urine from kidney to ureters - renal pelvis
includes renal veins and arteries - renal hilum
Nephron structure
Renal corpuscle:
glomerulus
glomerular capsule
afferent arteriole
efferent arteriole
(peritibular capillaries)
descending limb
loop of henle
ascending limb
proximal convoluted tubule
distal convoluted tubule
(renal tubule)
collecting duct
How blood goes through the kidneys?
The nephrons of the kidney are responsible for removing wastes from the blood and regulating blood composition.
they are supplied by blood vessels.
blood enters through the renal arteries.
renal arteries divide into small arteries and arterioles
renal capsules are supplied with arterioles
the afferent arteriole splits into a knot of capillaries called the glomerulus. located within the glomerular capsule.
capillaries untie to form the efferent arteriole which passes out the renal corpuscle.
after leaving, the efferent arteriole breaks into a second capillary network.
these capillaries are surrounded by a proximal and distal convoluted tube, ascending and descending limb, loop of henle and a collecting duct, these are known to be peritibular capillaries.
The blood drains from this network of capillaries and eventually leaves the kidney in the renal vein.
3 steps to get urine
The formation of urine from the nephrons of the kidneys involves 3 major processes:
- glomerular filtration
- selective reabsorption
- secretion by the tibules.
Glomerular filtration
- process takes place in the renal corpuscle
- fluid is forced out of the blood into the glomerular capsule.
- The afferent arteriole that comes in has a wider diameter than the efferent arteriole that goes out.
- The narrowing of the efferent arteriole increases resistance of flow of blood and produces a high pressure in the glomerular.
- high pressure results to more filtrate being pushed out.
- filtrate has to pass through 2 cell walls, 1 is the capillary wall the other is the capsule wall.
- it is a differentially permeable cell.
- filtrate consists of - urea, uric acid, creatinine, hormones, toxins, water, salts, amino acids, fatty acids, glucose and various ions.
- blood cells and plasma are too large to fit through the differentially permeable membrane.
Tubular reabsorption
- returning components back into the blood in the peritibular capillaries from the renal tubes.
- process carried out by the cells on the lining of the renal tubes.
- materials such as water glucose, amino acids and some ions ( Na+, K+, Cl-, HCO3-, Ca2+) are absorbed.
- large surface area is needed.
- large surface area is achieved by:
- long length of kindey tubule
- 2 sets of convolutions
- loop of henle
number of nephrons in the kidney. - reabsorbance of water can be regulates, depending on the bodies requirements.
- an active process, under hormonal control.
Tubular secretion
- Occurs in the distal convoluted tubule.
- adds material in filtrate from blood.
- K+, H+, creatinine and drugs (penicillin)
- can either be active or passive.
- maintains blood and urine PH
Movement after the kidneys
- final filtrate is drained from the collecting duct into the pelvis.
- pelvis drains urine into the ureters and is pushed by a wave of muscle contractions to be stored in the urinary bladder.
- ureters extend the pelvis to the kidney
- approx. 25cm - 30cm long toward the urinary bladder.
- the urethra carries urine from the bladder to the exterior of the body.
summary of functioning kidneys
Renal corpuscle:
- filtration of blood capillaries of glomerulus.
- formation of filtrate in the glomerulus capsule.
Proximal convoluted and loop of H:
- Passive R of K+, Cl-, HCO3-
- Active R of sodium and glucose.
- Passive R of Water through osmosis.
Distal convoluted :
- Secretion of hydrogen, potassium, ammonia and other drugs such as penicillin.
- Active R of sodium ions
- Active R of water, based on the bodies needs.
collecting duct: Active R of water based on bodies needs.
Composition of urine
- body must excrete waste products, such as urea, sulphate and phosphate on a regular basis.
- Disregarding water intake, at least 500ml of urine must be passed daily.
- elimination requires a water lost.
when water content is too low urine is highly concentrated.
- no significant amount of protein is found
- no glucose is found
urine contains:
96% of water
2% of urea
1.6% of various ions
0.4% of other substances.
Kidney stones
- formed from crystals that build up inside the kidneys
- usually formed when urine is too concentrated.
- due to insufficient fluids of the body.
- small crystals can flow out of the body with urine. They may form large stones.
- Large stones need to be extracted via breaking by sound waves or physical surgery.
- large stones block passages and pains can be intense.
Eccrine
- Found over most of the body
- drain directly to skin surface.
- secrete 500ml daily (up to 3L at times of thermal stress)
- Sterile watery sweat as salts is actively reabsorbed.
