Sec 32.4: Excretory System Flashcards
What is the excretory system?
It is the body system that eliminates nonsolid wastes through sweat, urine, and exhalation to help maintain homeostasis in the body
What are the waste products of the excretory system?
Toxic materials, excess water, salts, CO2, urea, minerals and vitamins
What are the main organs of the excretory system?
Skin, lungs, kidneys, ureters, urinary bladder, and urethra
What is the function of the lungs in the excretory system?
They remove CO2 and water vapor through exhalation
What is the function of the skin in the excretory system?
Sweat glands release excess water and salts to cool the body to maintain stable internal temperature
What are kidneys?
They are organs that eliminate wastes through filtration of the blood
How much of the blood supply passes through your kidneys?
1/4 of your blood supply every minute
What do kidneys look like? where are they located?
They are bean-shaped organs the size of a fist, located on the left and right sides of the lower back.
Where is blood returned after filtration?
To the circulatory system (duh)
What is the medulla?
The inner layer of the kidney
What is the cortex?
The outer layer of the kidney (packed with nephrons)
What are nephrons?
They are the individual filtering unit of the kidney. There are 1 million nephrons per kidney
Where does the blood enter and exit in the kidney?
Large volume of blood enters through the renal artery and exits through the renal vein.
What is the function of nephron controlled by?
By how much water, salts, & other materials are concentrated in the blood.
What helps regulate kidney function?
Hormones released in response to concentrations of water, salts, and other materials in the blood
What are the kidney’s three basic functions?
- Remove waste products from the blood, such as wastes from digestion and cell respiration
- Help to maintain electrolyte, pH, and fluid balances in the body
- Release hormones that help to keep bones healthy, produce red blood cells, and regulate blood pressure
What is the glomerulus?
It is a tangled ball of capillaries which supplies blood to each nephron. It is tucked into a cup-shaped structure called Bowman’s capsule
What is urea?
It is a waste product produced by breakdown of proteins
What is the ureter?
It is a tube that carries urine from each kidney to the bladder
What is the urinary bladder?
It is a saclike organ that can store up to half a liter (over 2 cups) of urine at one time
What is urethra?
It is the tube that releases urine
How do nephrons filter the blood and produce urine?
Filtration, Reabsorption, and Excretion
Describe the process of filtration
Blood enters kidney -> flows into arterioles -> moves into glomerulus of each nephron -> small molecules diffuse out of capillaries and into the Bowman’s capsule (forming the filtrate) -> blood cells, plasma, proteins, platelets stay in the blood because they are too big.
What is filtrate?
It consists of the small materials that diffuse into Bowman’s capsule such as water, electrolytes, amino acids, glucose, and urea
Describe the process of reabsorption
1% of filtrate is excreted as urine, and the other 99% is reabsorbed into the capillaries and returns to the blood
What does the reabsorption of H2O and Na+ do?
It helps maintain fluid balance
Why is reabsorption important?
Because it ensures nutrients are made available to the body
What is urine?
It is made up of water, salts, urea, and other materials that remain in the filtrate after reabsorption, and includes ions such as potassium and hydrogen.
Why is the removal of ions such as potassium and hydrogen important?
Because their removal maintains homeostasis by keeping blood pH within normal limits
What is the loop of Henle?
It is where water is removed one final time to reduce the volume of urine
Describe the process of Excretion
Filtrate moves out of Bowman’s capsule into loop of Henle, where water is reabsorbed one final time, and then remaining urine flows into a collecting duct that leads to the ureter -> urinary bladder
What happens when the bladder is full?
Bladder wall nerves send signals to the brain to get the urge to urinate
What is the importance of urine testing?
It determines whether a person is abusing drugs and what types, because drugs are broken down n he liver, filtered by the kidneys, and excreted in the urine
What does urine sample containing sugar, protein, or blood mean?
That there is possible nephron damage by an infection or injury
What are the possible causes of renal failure (kidney failure/damage)? What do they do?
Diabetes, high blood pressure, low blood pressure. They damage the capillary walls in the glomerulus and make them more porous, causing too many substances to pass through walls, so nephrons lose their ability to filter the blood
What are the treatments for kidney failure?
Transplants and dialysis
What is dialysis?
It is a treatment in which a patient’s blood is cleaned and chemically balanced through a mechanical process, and then returned to the patient’s body.
What must happen before and after a transplant?
Tissue must be similar enough that the recipient’s body will accept the new kidney, and recipient must take drugs that suppress the immune system for the rest of their life to guard against the possibility of the body rejecting the organ
