(B3) Urinary System Structure and Function Flashcards
What is the role of the kidney?
As an osmoregulatory organ to regulate the water content of the blood and filter it
As an excretory organ to excrete urea or substances in excess such as salts
What system are the kidneys a part of?
The excretory system
What brings blood towards the kidneys?
Aorta
What brings blood away from the kidneys?
Renal Vein to the Vena Cava
What is renal?
Renal relates to the kidneys
What does the renal artery do?
Carries oxygenated blood to the kidneys (contains urea and salts)
What does the renal vein do?
Carries deoxygenated blood from the kidneys
What is the renal artery connected to?
The Aorta
What is the renal vein connected to?
The Vena Cava
What is the ureter?
The passageway from the kidneys to the bladder that carries urine
What does the bladder do?
Stores urine temporarily
What is the sphincter muscle?
The muscle that opens and closes the pathway between the bladder and urethra
What is the urethra?
The tube that lets urine leave your bladder and body
What is the fibrous capsule?
A tough outer layer that surrounds the kidneys
What are the areas beneath the fibrous capsule?
- The Cortex
- The Medulla
- The Renal Pelvis
What does the cortex contain?
- The glomerulus
- The bowman’s capsule
- The proximal convoluted tubule
- The distal convoluted tubule
What does the medulla contain?
- The loop of Henle
- The collecting duct of the nephrons
What is the renal pelvis?
Where the ureter joins the kidney
What is a nephron?
The functional unit of the kidney which is responsible for the formation of urine
How many nephrons are there?
1-2 million per kidney
What is associated with each nephron?
A network of blood vessels
What is inside the bowman’s capsule?
The glomerulus
Where is the glomerulus supplied blood from?
From arterioles which have carried blood from the renal artery
What are arterioles?
Small blood vessels that carry blood, they are connectors between the arteries and capillaries
What do the capillaries of the glomerulus do?
They rejoin to form a arteriole which flows along the rest of nephron
The blood from here flows eventually into the renal vein
How does filtration happen in the nephron?
The blood vessels and the nephrons are interconnected (not linked) so waste is filtered through diffusion
What happens in the glomerulus?
Urea is filtered from the blood
Where does the urine go after leaving the Bowman’s Capsule?
- The Proximal Convoluted Tubule
- Loop of Henle
- The Distal Convoluted Tubule
- Collecting Duct
- Renal Pelvis
- Ureter
- Bladder
What is excretion?
The removal of waste substance of metabolic reaction, toxic materials and substances that are excess in requirement
What is a metabolic reaction?
The chemical reactions that take place inside the cell
What do the kidneys mainly excrete?
Excess water, salts and urea
What waste substances need to be removed from the blood?
- Uric Acid
- Ammonia
- Urea
- Creatine
- Excess Hormones
- Excess Water
- Excess Salt Ions (Na+, Cl-, Mg2+)
What are the two stages of urine production in the kidney?
- Ultrafiltration
- Selective Reabsorption
Where does ultrafiltration happen?
Bowman’s Capsule
Where does selective reabsorption happen?
Proximal Convoluted Tubule and the Loop of Henle
What is ultrafiltration?
Small molecules that are waste substances are filtered out of the blood capillaries of the glomerulus into the Bowman’s capsule to form glomerular filtrate
What is selective absorption?
Useful molecules are reabsorbed from the glomerular filtrate and is returned to the blood as the filtrate flows along the nephron
What is osmoregulation?
The control of the water potential of the body’s fluids
What is osmoregulation a part of?
Homeostasis
What is homeostasis?
The process of keeping everything in the body the same
What are osmoreceptors?
Specialized sensory neurons that monitor the water potential of the blood
What happens if the osmoreceptors detect a decrease in the water potential of the blood?
Nerve impulses are sent along the sensory neurons to the posterior pituitary gland
What happens when the posterior pituitary gland receives nerve impulses?
It releases ADH
What is ADH?
Antidiuretic Hormone
What does ADH do?
Causes the kidneys to reabsorb more water which reduces the loss of water that happens through urine
ADH cycle if too much water is drunked
- Water content of the blood is high
- Brain produced less ADH
- Low volume of water is reabsorbed by kidney
- Urine output is high
What is dialysis?
A procedure that acts as an artificial kidney to remove urea as well as maintain the water and ion balance of the blood
Why is dialysis needed?
Humans can only survive if they have at least one kidney, dialysis is used for those who suffer from total kidney failure
How does the dialysis machine work?
Blood is taken out of the body and given an anti-coagulant
Then the blood passes by dialysis fluid where diffusion will occur removing urea
After the blood passes through a air detector and then goes back into the body
What is a anti-coagulant?
Something added to the blood to stopping it clotting after being exposed outside of the body
What is in the dialysis fluid and how much is needed?
A normal level of concentration of glucose and ions so that a normal amount glucose and ions remain in the blood because the concentration gradient is the same
The dialysis fluid needs to be in a constant fresh supply to get rid of the urea it has collected
Advantages of Dialysis
- Reduced levels of urea in blood
- No change in the amount of water, ions and glucose in the body
Disadvantages of Dialysis
- Expensive
- Dialysis is needed multiple times a week for a long period of time
