excretory system Flashcards
what is the difference between the afferent and efferent arteriole
Afferent arteriole has a wider diameter than the efferent arteriole
efferent arteriole carries blood into the nephron, efferent carries blood away
what are the 3 processes of urine formation
Glomerular filtration
Selective reabsorption
Tubular secretion
explain the process of glomerular filtration
occurs in renal corpuscle
- Small substances move from the glomerulus into the glomerular capsule
- Afferent arteriole leading into glomerulus is much wider than efferent arteriole leaving it
- This increases resistance in blood flow and creates high pressure in the capillaries
- Capillaries force water and undissolved blood components through it’s membrane into the glomerulus capsule
- What’s left behind is residue
• Blood cells
• Proteins
what substances are involved during glomerular filtration
- Water
- Urea
- Glucose
- Amino acids
- Vitamins
- Salt (sodium & chloride ions)
how is glomerular filtration enhances
- increasing pressure and resistance in the glomerulus forces substances out
- Cells of the glomerular capsule and capillaries are 1
cell thick - New blood is constantly brough the glomerulus and
keeps a concentration difference of the substances
explain the process of selective reabsorption
Occurs in tubule of nephron and its surrounding peritubular capillaries
Many components of filtrate are useful, so the body uses selective re-absorption to take back what it needs
Must be large surface area achieved by:
- Long length of renal tubule, created by convolution and
loop of Henle
- Large number of nephrons in each kidney
what substances are reabsorbed in the loop of henle during selective reabsorption
ions
what substances are reabsorbed in the proximal convoluted tubule during selective reabsorption
Water Glucose Amino Acids Vitamins Salts
what substances are reabsorbed in the distal convoluted tubule during selective reabsorption
water and salt (depending on needs of body)
Water is moved by FACILITATED REABSORPTION
explain the process of tubular secretion
Body removes unwanted waste and regulates pH levels
Substances are secreted back into the tubules
what substances are removed during tubular secretion
Hydrogen ions Ammonium Creatinine Toxins Drugs
what is a nephron
functional unit of the kidney, its where urine is formed
Kidneys are composes of a large number of nephrons
About 2 million nephrons in each kidney
what is the function of the kidneys
primary excretory organs
explain the process of deamination
Metabolic process (in the liver) that breaks down excess protein so it can be excreted
Part 1:
Excess proteins are broken down in the liver into amino
acids
The NH2 amino group is removed from the amino acid
The NH2 group is converted into ammonia
Amino acid + oxygen ——enzymes—-> carbohydrate + ammonia
Part 2:
The remains of the amino acid is converted into a carbohydrate which is used to release energy, CO2 and water
Ammonia is highly toxic to cells so it is quickly converted into the less toxic urea
Urea is excreted in the form of urine, small amounts are lost in in sweat
Energy + carbon dioxide + ammonia —–> urea + water
what is the function of the skin
Provide protective covering over surface of the body
Regulate body temperature
Plays important role in excretion
- Sweat gland are located in lower layers of skin
- A duct carries the sweat to a hair follicle or skin surface
where it opens at a pore
- Cell surrounding the glands are able to contract and
squeeze the sweat to the surface
- Glands secrete about 500mL water per day
- Dissolved in it are:
o Sodium chloride
o Urea
o Lactic acid
o Some drugs e.g. salicylic acid
