Excretory System

Question 1

main functions of the kidney (6)

Answer 1

• Ion balance – especially Na+ and K+
• Osmotic balance – determine volume of urine produced
• Blood pressure – controls blood volume and ECF volume (extra cellular fluid)
• pH balance – retains or excretes H+ or HCO3
• Excretion – of nitrogenous wastes or other hydrophilic toxins
• Hormone production

Question 2

kidney anatomy

Answer 2

• Renal cortex (more on the outside)
• Renal medulla (more inside)
• Pelvis inside

Question 3

where does blood enter the kidneys

Answer 3

renal artery

Question 4

bowmans capsule

Answer 4

Mouth of the tubules, cuplike expansion surrounding the glomerulus

Question 5

nephrons

Answer 5

• Perform primary task of removing waste products
• Composed of two elements: Glomerulus, Renal tubule

Question 6

glomerulus (nephrons)

Answer 6

twisted ball of capillaries (small blood vessels), delivers to the tubule

Question 7

renal tubule (nephrons)

Answer 7

composed of single layer of cells

Question 8

what do hormones and neurotransmitters do in the excretory system

Answer 8

ensure urine composition and the release of the urine matched to the physiological needs of the animal

Question 9

what are the four processes involved in urine formation

Answer 9

filtration, reabsorption, secretion, excretion

Question 10

filtration (in the glomerulus)

Answer 10

• As blood flows into each nephron, it enters a cluster of tiny blood vessels – the glomerulus
• thin walls of glomerulus allow smaller molecules, wastes, and fluids to pass into the tubule
• larger molecules, such as proteins and blood cells stay in the blood vessel

Question 11

reabsorption (PCT, DCT, collecting duct)

Answer 11

• Recovery from substances from the lumen of the tubule
• Most molecules are reabsorbed through a combination of facilitated diffusion and active transport

Question 12

secretion (loop of henle, dct, collecting duct)

Answer 12

• Transfer of solutes from the blood into the tubule lumen
• Uses transporters found in the cells that line the lumen
• Most important secretory products are K+, NH4+, and H+

Question 13

how much urea is in final urine vs. primary urine

Answer 13

primary: 0.03 final: 2.00

Question 14

how much salt is in final urine vs. primary urine

Answer 14

primary: 0.72 final: 1.50

Question 15

what are the main hormones involved in the excretory system

Answer 15

ADH (antidiuretic hormone), Aldosterone

Question 16

ADH in excretory system

Answer 16

• Main hormone responsible for the recovery of water
• High ADH levels increase reabsorption of water by the collecting duct

Question 17

aldosterone in excretory system

Answer 17

• Regulates sodium and potassium balance
• Stimulates Na+ reabsorption and enhances K+ excretion

Question 18

bladder
how does urine enter and exit, what controls closing and opening of sphincter

Answer 18

• Urine leaves kidney and enters urinary bladder via ureters for storage
• Exits via urethra: sphincters of smooth muscle control flow
• Opening and closing of sphincter influenced by voluntary and involuntary controls