Excretory System

Question 1

structures of the urinary/excretory system

Answer 1

• pair of kidneys
• pair of ureters
• bladder
• urethra

Question 2

what are the 2 functions of the excretory system

Answer 2

• regulates the chemical composition and volume of body fluids - osmoregulation
• removes nitrogenous waste products and excess water

Question 3

what is the kidney split into

Answer 3

• split into the medulla (inner) and the cortex (outer)

Question 4

the nephron

Answer 4

• the functional unit of the kidney - contains around a million nephrons
• network of arterioles form the glomerulus which sits in the glomerular
• each nephron consists of a glomerular capsule, proximal convoluted tubule, loop of henle and distal convoluted tubule
• a collecting duct serves a number of nephrons and drains into a ureter

Question 5

how is urine formed

Answer 5

• blood is at a high pressure when it enters the glomerulus causing water and small molecules to filtrate through into the Bowman’s capsule. The process is called ultrafiltration
• the filtrate is very dilute and contains 99% water and 1% waste products
• The filtrate than passes through the rest of the nephron
• once the filtrate passes into the collecting duct it is called urine

Question 6

osmoregulation as a homeostatic mechanism

Answer 6

• selective reabsorption - water, sodium, chloride, glucose
• secretion of substances
  include urea, drugs, toxins
• osmoregulation - volume of plasma and the concentration of dissolved chemicals and other tissue fluids remains constant