The Urinary System

Question 1

What are the components of the urinary tract?

Answer 1

2 kidneys 
2 ureters 
the bladder
a urethra
the urogenital system (penis/vulva)

Question 2

What is a ureter?

Answer 2

Long tubes composed of 3 layers: the mucous lining, the muscular middle layer and the fibrous outer layer. They remove urine from kidneys down the the bladder.

Question 3

What is the urinary bladder?

Answer 3

Predominately smooth muscle arranged in criss crossing bundles. Has a GAG lining that helps protect the epithelial cells from acidity. These cells allow contraction and extension. There is 1 exit and two entrances

Question 4

What are the functions of the urinary bladder?

Answer 4

• acts as a reservoir for urine

- expels urine when it becomes full

Question 5

What is the urethra?

Answer 5

A small tube that exits the bladder

Question 6

What is the process of voiding urine?

Answer 6

Involves voluntary relaxation of the external sphincter, parasympathetic contractions of the muscular regions and the internal sphincter. Urine is then forced out through the urethra

Question 7

Define the KIDNEY

Answer 7

The kidneys are each a pair of organs in the abdominal cavity that excrete urine

Question 8

Define NEPHRON

Answer 8

A nephron is the functional unit in the kidney, consisting of the glomerulus and its associated tubule, through which the glomerular filtrate passes before emerging as urine. The loop of henle is in it.

Question 9

Define the GLOMERULUS

Answer 9

The glomerulus is tufts of capillaries surrounded by Bowman’s capsules. It is a a major site for the filtration of blood. It filters 100 times as much liquid as urine is excrted.

Question 10

What is the filtration rate?

Answer 10

The amount of filtrate that forms in all renal corpuscles every minute. For humans it is about 180l per day.

Question 11

Define HOMESTASIS

Answer 11

Homeostasis is the process of maintaining a constant internal environment. Uses negative feedback:

• if pressure is too high, substances go through too fast and not enough is absorbed
• if pressure is too low, high levels of waste build up in the body

Question 12

Define ANGIOTENSIN

Answer 12

Angiotensin is a protein whose presence in the blood tends to raise blood pressure. It constricts blood vessels and encourages the reabsorption of sodium and water, stimulating thirst.

Question 13

Define the LOOP OF HENLE

Answer 13

The loop of henle is the part of the kidney tubule which forms a long loop in the medulla from which water and salt are reabsorbed into the blood.

Question 14

Define OSMOSIS

Answer 14

Osmosis is the process by which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solutions to a more concentrated one

Question 15

Define TUBULAR SECRETION

Answer 15

Tubular secretion is the process by which materials are removed from the blood such as excess potassium and hydrogen and foreign chemicals

Question 16

Define VASOPRESSIN

Answer 16

Vasopressin is the hormone secreted from the posterior pituitary which controls permeability of the collecting duct. If it is absent, more dilute urine is formed as more water is secreted.
If it is present/increased, more concentrated urine is formed as more water is reabsorbed back into tissues.

Question 17

What is a Bowman’s capsule?

Answer 17

A cup-like sack at the beginning of the tubular component of a nephron in the kidney that performs the first step in the filtration of blood to form urine.

Question 18

Define the URINARY SYSTEM

Answer 18

The urinary system is a system whose main function is to remove waste products from the blood in the form of urine