Chapter 13 Flashcards
Excretion (Kidneys)
What is Excretion?
Excretion is the removal of waste products, excess substances and toxic materials. (spent hormones and drugs too)
What are the Excretory organs?
- Liver
- Lungs
- Kidneys
- Skin (not an organ)
What is the role of the Liver?
- The Liver is where the Deamination and Assimilation of amino acids takes place.
What is Deamination?
Deamination is the removal of the Nitrogen- containing part of amino acids to form Urea. (Glycogen too)
*This is because excess Amino acids cant be stored
What is Assimilation?
Assimilation is the absorption of substances which are built into other compounds in the organism.
How is Urea formed?
It is formed in the Liver from excess amino acids.
What is the importance of Excretion?
The build up of some compounds like products of reactions, can be toxic if not removed.
What happens if Carbon Dioxide builds up?
Carbon dioxide dissolves in fluids (tissue fluid/blood plasma) to for Carbonic acid.
The increase in acidity may affect the action of enzymes and be fatal.
What happens if theres build up of Urea? (how is it removed?)
When amino acids are broken down, Ammonia is made in the liver, which is very alkaline and toxic.
- Ammonia is converted to Urea, which is less poisonous and the nitrogen is safely excreted.
What is Bilirubin?
- Bilirubin is a green/yellow bile pigment thats the breakdown product of Hemoglobin.
- It is excreted with bile into the small intestine, and expelled with faeces.
*The pigment undergoes color change thats responsible for the brown color of faeces.
What is the role of the Lungs?
The lungs get rid of Carbon Dioxide and theres also the incidental loss of a great deal of water vapour.
What is the role of the Kidneys?
The kidneys excrete Urea, excess water and salts, spent hormones and drugs (urine).
What is Urine?
Urine is a watery solution of nitrogenous waste products, excess salts, water and spent hormones that is excreted by the Kidneys.
Explain the structure of the kidneys (Kidneys, ureter, bladder, urethra)
- The kidneys are two, solid oval structures that are red-brown, enclosed in a transparent membrane and attached to the back of the abdominal cavity.
- A tube called the Ureter runs from each kidney to the bladder
- The Urethra, expels urine.
What is the Renal artery and vein?
- The Renal Artery branches off the Aorta, bringing OXYGENATED blood towards the kidneys.
- The Renal Vein carries DEOXYGENATED blood away from the Kidneys, towards the Vena Cava of the heart.
What is the Cortex and Medulla?
These are the regions inside of the Kidney.
- The Cortex is the outer darker region.
- The Medulla is the inner lighter area.
What is a Glomerulus?
A Glomerulus is a capillary thats repeatedly divided and coiled to make a knot of vessels.
What are the parts of a Glomerulus? (including: Renal capsule, tubule, collecting duct)
- Each Glomerulus is surrounded by a cup-shaped organ called the Renal Capsule.
- This Capsule leads to a coiled Renal Tubule.
- The Renal Tubule joins a collecting duct, which passes through the Medulla to open into the Pelvis.
What is the importance of Glomerulus?
Glomerulus help filter the blood, and provide a large surface area.
What is a Nephron?
A Nephron is a single Glomerulus with its renal capsule, renal tubule and blood capillaries.
How many Nephrons are in a Kidney?
There are up to 4 million Nephrons in a Kidney.
What is Ultrafiltration? (Explain)
Ultrafiltration is the process by which fluid is filtered out of the blood by the Glomerulus.
What is the fluid that filters through the capillary?
This is Plasma without proteins.
It consists of mainly water and dissolved salts, glucose, urea and uric acid.
What is Selective Reabsorption?
This is the process of absorbing substances needed by the body during Filtration.
Which substances are reabsorbed during ultrafiltration?
First all of the Glucose and most water is reabsorbed back.
Then some salts are taken back to keep the correct concentration in the blood.
What continues to pass down the Renal tubule?
Excess salts and nitrogenous waste products (Urea & Uric acid).
What happens after fluid passes down the renal tubule?
The fluid moves into the pelvis of the kidney. Here the fluid is now called Urine.
It passes down the Ureter and is stored in the Bladder.
How much urine can the bladder hold?
The bladder can expand to hold 400cm3 of urine.
What is the Sphincter?
It is a band of circular muscle that when relaxed, expels urine from the Urethra.
