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Flashcards in excretory system Deck (15)
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1

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

2

what are the 3 processes of urine formation

Glomerular filtration

Selective reabsorption

Tubular secretion

3

explain the process of glomerular filtration

occurs in renal corpuscle

1. Small substances move from the glomerulus into the glomerular capsule

2. Afferent arteriole leading into glomerulus is much wider than efferent arteriole leaving it

3. This increases resistance in blood flow and creates high pressure in the capillaries

4. Capillaries force water and undissolved blood components through it’s membrane into the glomerulus capsule

5. What’s left behind is residue
• Blood cells
• Proteins

4

what substances are involved during glomerular filtration

• Water
• Urea
• Glucose
• Amino acids
• Vitamins
• Salt (sodium & chloride ions)

5

how is glomerular filtration enhances

1. increasing pressure and resistance in the glomerulus forces substances out

2. Cells of the glomerular capsule and capillaries are 1
cell thick

3. New blood is constantly brough the glomerulus and
keeps a concentration difference of the substances

6

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

7

what substances are reabsorbed in the loop of henle during selective reabsorption

ions

8

what substances are reabsorbed in the proximal convoluted tubule during selective reabsorption

Water
Glucose
Amino Acids
Vitamins
Salts

9

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

10

explain the process of tubular secretion

Body removes unwanted waste and regulates pH levels

Substances are secreted back into the tubules

11

what substances are removed during tubular secretion

Hydrogen ions
Ammonium
Creatinine
Toxins
Drugs

12

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

13

what is the function of the kidneys

primary excretory organs

14

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

15

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