Ch 8 Excretion in Humans

Question 1

Define excretion.

Answer 1

Excretion is the removal of metabolic waste products, toxic substances, and substances in excess of the body’s requirements.

Question 2

Metabolic waste product: Carbon dioxide
1. How it is produced
2. How it is excreted
3. Too much can cause

Answer 2

CARBON DIOXIDE
1. Waste product of aerobic respiration
2. Removed through gaseous exchange in the lungs
3. Headaches, rapid breathing, confusion

Question 3

Metabolic waste product: Urea
1. How it is produced
2. How it is excreted
3. Too much can cause

Answer 3

UREA
1. EXCESS amino acids are DEAMINATED in the liver
2. As urine through the kidneys, and as sweat through the skin.
3. Nausea, vomiting.

Question 4

Metabolic waste product: Mineral salts and ions
1. How it is produced
2. How it is excreted
3. Too much can cause

Answer 4

MINERAL SALTS AND IONS
1. EXCESS mineral salts and ions from food.
2. As urine through the kidneys, and as sweat through the skin.
3. Blood WP < Body cells WP. Water moves out of cells. Cells become dehydrated and crenated.

Question 5

Metabolic waste product: Water
1. How it is produced
2. How it is excreted
3. Too much can cause

Answer 5

WATER
1. Produced as a product of aerobic respiration/from food or drinks.
2. As urine through the kidneys, and as sweat through the skin.
3. Blood WP > Body cells WP. Water moves into cells. Cells expand and burst. (Haemolysed for RBC)

Question 6

Why is excretion important?

Answer 6

So that toxic substances will not build up in the body and cause harm.

Question 7

Parts of the urinary system in order and their functions.

Answer 7

1. Kidney (excrete urea and excess salt and water as urine. receives blood from the renal artery, returns blood through the renal vein. has a basic functional unit called a nephron.)
2. Ureter (tube connecting kidney and urinary bladder)
3. Urinary bladder (stores urine)
4. Urethra (urine is passed from here out of the body)

Question 8

In the kidney: What are the parts of the nephron in order?

Answer 8

1. Bowman’s capsule (C-shaped)
2. Proximal (nearer) convoluted tubule (wavy-shaped tube)
3. Loop of Henle (U-shaped tube)
4. Distal (further) convoluted tubule (wavy-shaped tube)
5. (Not in the nephron, but closely associated) Collecting duct

Question 9

In the kidney: What are the blood capillaries around the nephron in order?

Answer 9

NOT IN KIDNEY:
1. Renal artery (branches out into arterioles when inside the kidney)

SURROUNDING KIDNEY NEPHRON:
2. Afferent arteriole (Small branch the renal artery leading into the Bowman’s capsule)
3. Glomerulus (Knot of blood capillaries inside the Bowman’s capsule)
4. Efferent arteriole (Transports blood away from the Bowman’s capsule)
5. Blood capillaries surrounding the nephron
6. Venules (Blood vessels connecting the venous end of capillaries to the veins)

NOT IN KIDNEY:
7. Renal vein (joined together by venules)

Blood vessel order:
Artery > Arteriole > Capillary < Venule < Vein