excretory system Flashcards
what is excretion
removal of the wastes of metabolism from the body is called excretion
what parts of the body are involved in the processing and excretion of wastes
the lungs, the liver, the alimentary canal, sweat glands and the kidneys
what are kidneys
kidneys are the principal excretory organs as they are responsible for maintaining material in bodily fluids.
what do the kidneys excrete?
nitrogenous wastes urea (which is produced from the breakdown of amino acids in the liver), uric acids and creatinine are the most toxic wastes excreted by the kidneys.
deamination + why does it occur?
deamination is the removal of the amino group (NH2) from amino acids so that the remaining part can form carbohydrates to be used for energy production that occurs in the liver with the aid of enzymes.
amino acid + oxygen → carbohydrate + ammonia
* carbohydrate → energy
* amine group → ammonia → urea + water
deamination occurs for use of proteins as they produce energy
functions of the liver
- preparation of materials for excretion
- Detoxifies alcohol, other drugs
- Deactivates many hormones and converts them into a form thatcan be excreted by the kidneys
- Breaks down haemoglobin to produce bile pigments (passed outof the body with the faeces)
skin: function + role in excretory system
Function: provide protective covering over surface of the bodyand to regulate body temperature
- sweat glands located in the low layers of the skin, duct carries sweat to follicle or to skin surface
- cells around the glands contract which squeeze the sweat to the surface of the skin
kidney function
- removes waste from the blood
- regulates water content and the pH of blood
renal artery
carries blood to kidney
renal vein
carried blood away from kidneys
medulla
inner part of kidney
cortex
outer part of kidney
renal pelvis
funnels urine into ureter
nephrons
nephrons are the functional units of the kidney. there is around one million nephrons in each kidney.
parts of the nephron (12)
- renal artery and renal vein
- afferent arteriole
- glomerulus
- bowman’s capsule
- efferent arteriole
- peritubular capillaries
- proximal convoluted tubule
- descending loop of henle
- ascending loop of henle
- distal convoluted tubule
- collecting tubule
three major processes in the production of urine
- glomerular filtration
- selective tubular reabsorption
- tubular secretion
glomerular filtration
This is the first step of the formation of urine. Blood is filtered in the renal capsule as the blood travels through the glomerulus. This filtrate is collected in the glomerular capsule.
selective tubular reabsorption
Selective absorption of useful substances including water, glucose, amino acids and some ions occurs in the proximal convoluted tubule, the loop of Henle, the distal convoluted tubule and collecting duct.
tubular secretion
Tubular Secretion moves substances such as drugs, potassium, creatinine and hydrogen ions from the blood to the urine in the distal convoluted tubule.
where does urine go after moving to the collecting ducts?
urine then travels through the collecting ducts to the renal pelvis to the ureters. then urine travels to the bladder where it is stored then is excreted through the urethra.
what is micturition?
process of excreting urine through urethra.
what occurs in the collecting duct?
active reabsorption of water, depending on the body’s water needs
what occurs in the renal corpuscle?
- filtration of blood from capillaries of glomerulus
- formation of filtrate in the glomerular capsule
what occurs in the proximal convoluted tubule and the loop of henle?
- passive reabsorption of potassium, chloride and bicarbonate ions
- active reabsorption of glucose and sodium
- passive reabsorption of water by osmosis
what occurs in the distal convoluted tubule
- active reabsorption of sodium ions
- active reabsorption of water, depending on body’s water needs
- secretion of hydrogen and potassium ions, creatinine and certain drugs such as penicillin
how much of the filtrate is turned into urine?
only 1%
concentration of urine
very high
waste products in urine
urea, sulfates and phosphates, these are created as solution in the urine
chemical components of urine
water (main component), sodium, chloride and other ions, proteins, glucose, urea, uric acid + creatinine
kidney stone
when urine becomes too concentrated, solid crystals form
kidney failure
occurs when the kidneys lose their ability to excrete wastes and control the level of fluid in the body
peritoneal dialysis
dialysis occurring inside the body, using the peritoneum as the membrane across which wastes can be removed
dialysis
method of removing wastes from the blood when kidney failure occurs.
haemodialysis
passing the blood through an artificial kidney or dialysis machine
liver disease
when the liver is not able to function effectively, it is hbavke to process toxins for elimination.
can be caused by infection, autoimmune problems, genetic disorders, cancer and lifestyle factors
