The Excretory System Flashcards
(31 cards)
What is the purpose of the excretory system?
To remove waste from the body
What 5 main waste products does the body remove?
Water
Carbon dioxide
Salts
Heat
Nitrogen
What is the first stage of waste removal?
Blood entry and filtration
What happens during blood entry and filtration?
1.blood enters the kidney through the renal artery
2.inside the kidneys nephron filter the blood:
Blood enters the glomerulus, the blood is filtered allowing waste products to pass into the bowman’s capsule while keeping back important structures like leukocytes (using ultrafiltration)
- The filtrate moves to the proximal tubule. The process of reabsorption begins:
Sodium, potassium, water, glucose and amino acids are absorbed into the proximal tubule. - The filtrate moves onto the loop of henle
What is the second stage of waste removal?
Tubular reabsorption
What happens during tubular reabsorption?
The tubule selectively reabsorbs essential substances back into the bloodstream through the peritubular capillaries
The tubule also secreted additional waste products (hydrogen ions and excess potassium) from the blood into the filtrate
How does ultrafiltration work?
The hydrostatic pressure forced the small molecules to leave the glomerulus and enter the capsule.
Cells and proteins are not able to pass due to size.
What is hydrostatic pressure?
The pressure existing in stationary fluids
What is osmosis?
High water potential -> low water potential
In the direction that tends to equalise the solute concentrations on both sides.
What products are absorbed into the proximal tubule?
Sodium
Potassium
Glucose
Amino acids
Water
What happens in the ureter?
Urine is moved to the bladder using peristaltic contractions
What are the ureters lined with?
Transitional epithelium
What is transitional epithelium?
Several layers of cells that become flattened when stretched
What is the mucosa?
Inner layer, has folds called rugae when the bladder is empty it allows for expansion as it fills
What is the submucosa?
Layer of connective tissue supporting the mucosa
What is the muscularis?
Layer of smooth muscle called the detrusor muscle which contracts to expel urine
What is the outer layer of the bladder?
Parietal petritoneum on the surface and fibrous connective tissue elsewhere
What is Parietal petritoneum?
A serous membrane (smooth tissue)
Is the bladder under voluntary or involuntary control?
The bladder is under both
Is the external urethral sphincter under voluntary or involuntary control?
Voluntary
Is the internal urethral sphincter under voluntary or involuntary control?
Involuntary
Are the bladder muscles under voluntary or involuntary control?
Involuntary
Where is the internal urethral sphincter located?
The bladder neck
What does the internal urethral sphincter do?
Allows urine into the urethra
