Urinary System

Question 1

Functions of the Urinary System

Answer 1

• Removal of waste products
• Assist liver to detoxify poisons
• Regulating blood volume and pressure
• Regulating plasma concentration of Na+, K+, Cl-
• Helping to stabilise blood pH
• Conservation of valuable nutrients

Question 2

Kidneys location

Answer 2

location: abdominal cavity Left kidney is superior to right. They are surrounded by fat and surface is capped by the adrenal gland.

Question 3

Ureters

Answer 3

• Paired: transports urine towards the urinary bladder
• Exits the kidney at the renal hilum
• Approx. 30cm long
• Contains smooth muscle for peristalsis
• Lined with transitional epithelium

Question 4

Urinary Bladder:

Answer 4

• Muscular: smooth muscle – detrusor muscle
• Collects and stores urine for excretion
• Highly distensible
• Lined by transitional epithelium
• Stretch receptors contained within the walls: micturition reflex
  discharge of urine involves muscle involuntary and voluntary muscle contractions
  stretch receptors trigger reflex

Question 5

Urethra:

Answer 5

• Transports urine from the bladder for external excretion
• Significant anatomical difference between males and females
• Begins at and form the base of the trigone within the urinary bladder
• Transitional epithelium -> non-keratinised stratified squamous epithelium

Question 6

Male Urethra:

Answer 6

5 times loner & divided into three segments. The urethra is a common duct for the urinary and reproductive systems in males

Question 7

Female Urethra:

Answer 7

shorter and only one short tube. The urinary and reproductive systems are completely separate in females.

Question 8

Nephron Function:

Answer 8

• filtering blood
• reabsorbing useful material from blood filtrate
• secretion of wastes into the urine

Question 9

Blood vessels of the nephron:

Answer 9

• Deliver blood to nephron so it can be filtered

- Facilitate exchange of substances

Question 10

Two main parts of nephron:

Answer 10

• Renal Corpuscle

- Renal Tubule

Question 11

Renal Corpuscle consist of:

Answer 11

• Glomerulus (a tuft of fenestrated capillaries) which form a high-pressure capillary bed
• The double layered glomerular (Bowman’s) capsule which wraps around t he capillaries
  - Visceral layer composed of podocytes

Question 12

Renal Tubule consists of:

Answer 12

filtrate is processes and modified into urine. consists of:

• Proximal Covoluted tube (PCT)
• Loop of Henle
• Distal Convoluted tubule (DCT)
• Collecting Duct

Question 13

Steps in urine formation:

Answer 13

1. Glomerular filtration: in the glomerulus blood plasma and dissolved substances get filtered into the glomerular capsule
2. Tubular Reabsorption: along the renal tubule and collecting duct, water, ions, and other substance get reabsorbed from the renal tubule lumen into the peritubular capillaries and ultimately into the blood
3. Tubular Secretion: along the renal tubule and collecting duct, substances such as wastes, drugs, and excess ions get secreted from the peritubular capillaries into the renal tubule. These substances ultimately make their way into the urine

Question 14

regulation of water output:

Answer 14

• urine volume & concentration regulated by ADH
• acts on collecting ducts
• Water re-absorption in collecting ducts is proportional to ADH release
• Decreased = dilute urine and decreased volume of body fluids
• Increased = concentration urine

Question 15

Aldosterone Regulation of Sodium & Potassium

Answer 15

aldosterone -> active re-absorption of Na+ & secretion of K+

Question 16

Renal Tubule - Proximal Convoluted Tubule

Answer 16

• Directly attached to renal corpuscle
• Lined with simple cuboidal epithelium
• Microvilli on apical surface increases surface area
• Much of filtrate is reabsorbed (esp. water, glucose, amino acids, & ions)
• Secretion helps to manage pH and rid the body of toxic and foreign substances

Question 17

Renal Tubule - Loop of Henle

Answer 17

• Descending and ascending regions

- Works to establish a salt concentration gradient in the medulla to promote recovery of water from filtrate

Question 18

Descending limb of loop of henle:

Answer 18

• Freely permeable to H2O
• Not permeable to NaCl
• Filtrate becomes increasingly concentrated as H2O leaves by osmosis

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Question 19

Ascending limb of Loop of Henle

Answer 19

• Impermeable to H2O
• Preamble to NaCl
• Filtrate becomes increasingly dilute as salt is reabsorbed

Question 20

Renal Tubule - Distal Convoluted Tubule (DCT)

Answer 20

• Functions more in secretion tan reabsorption
• Recovery of water and sodium is influenced by hormones
  
  • Aldosterone stimulates sodium reabsorption
  • Antidiuretic hormone (ADH) stimulates water reabsorption

Question 21

Renal Tubule - Collecting Duct:

Answer 21

• Receive filtrate from many nephrons
• Fine tuning of water recovery or disposal
• Water reabsorption through aquaporins regulated by ADH
• Fuse together to deliver urine through renal papillae into minor calyces