11.3 Flashcards
Define osmolarity
Osmolarity refers to the solute concentration of a solution
Define osmoregulators
Osmoregulators are animals that maintain their internal environment regardless of the external environment
- Most animals are osmoregulators
Define osmoconformers
Osmoconformers are organisms that change according to their external environment
- Animals whose internal solute concentration tends to be the same as the concentration of solutes in the environment
How are nitrogenous wastes produced?
Nitrogenous wastes are produced from the breakdown of…
- Amino acids (a part of proteins)
- Nucleic acids
What are the 3 types of waste molecules that the amine group (NH2) is incorporated into?
- Ammonia
- Urea
- Uric acid
How do insects carry out osmoregulation and the removal of nitrogenous wastes?
The Malpighian tubule system
- Tubes that branch off from their intestinal tract (Malpighian tubules)
What is osmoregulation?
It is a form of homeostasis whereby the concentration of hemolymph or blood in the case of animals with closed circulatory systems is kept within a certain range
What is hemolymph?
Arthropods have a circulating fluid, known as hemolymph
It is a combination of
- The characteristics of tissue fluid
- Blood
Waste products of any type of organism must be excreted out, explain the toxicity of each nitrogenous waste and how it is excreted
- Ammonia; Very very very very very very toxic
- Urea; not that toxic
- Uric acid; not toxic
The more toxic the waste molecule is, the more water it requires to dilute it
- Leading it to be excreted out of the organism
What do the cells lining the Malpighian tubules do?
Actively transport ions and uric acid from the hemolymph into the lumen of the tubules
What happens to the water and salt in the process of excretion in the Malpighian tubule?
Water is drawn out by osmosis from the hemolymph through the walls of the tubules into the lumen
- The tubules empty their content into the gut
- Both water and salts are reabsorbed into the hind gut while the nitrogenous waste is excreted with the feces
What is the function of the kidneys?
- Osmoregulation
- Excretion
They are responsible for removing substances from the blood that are not needed or are harmful
What is the difference between the composition of blood in the renal artery and the renal vein?
Renal artery; Where blood enters the kidney
Renal vein; Where blood leaves the kidney
There are substances that are present in higher amounts in the renal artery than the renal vein
What are the substances that are presented in higher amounts in the renal artery than the renal vein?
- Toxins and other substances that are ingested and absorbed but are not fully metabolised
- Excretory wast products; Including nitrogenous waste products
- Excess water, produced by cell respiration/ absorbed from food in the gut
- Excess salt, absorbed from food in the gut
What is the removal of excess water and salt a part of?
Ultrafiltration
The process of excretion
Describe the difference in the water and or salt content in the blood in the renal artery and the renal vein
Blood in…
Renal artery; Contains more water and salt content but in a lower concentration
Renal vein; Contains more constant concentration of water and salt because osmoregulation has occurred
What does the kidney filtrate and absorb and where are the filtrated substances found?
Filtrate
- It filters off about one fifth of the volume of plasma from the blood flowing through them
- Filtrate contains all of the substances in plasma apart from large protein molecules
Absorb
- It actively reabsorbs the specific substance in the filtrate that the body needs
The unwanted substances can only be presented in the renal artery and NOT the renal vein!!!
How does the metabolic activity of the kidney affect the difference between the composition of blood in the renal artery and the renal vein?
Oxygen
Blood leading the kidney = deoxygenated
Blood entering the kidney = oxygenated
- The kidney metabolism requires oxygen
Glucose
More in renal artery than in renal vein
Due to the fact that some glucose is used by the metabolism of the kidney
What is not filtered by the kidney and is presents in the same concentration in both blood vessels?
Plasma proteins
What is the use of the ultra structure of the glomerulus and the Bowman’s capsule?
To facilitate ultrafiltration
Describe the pressure in the capillaries in the glomerulus of the kidney
- Pressure in the capillaries is particularly high
- The capillary wall is particularly permeable; Making the volume of the fluid forced out to be about 100 times greater than in the other tissues
What is the name of the fluid forced out of the capillaries of the glomerulus of the kidney?
Glomerulus filtrate
What is ultrafiltration?
The separation of particles differing in size by a few nanometers
What is the podocyte and what is it’s function?
A strangely shaped cell with finger-like projections which wrap around capillaries in the glomerulus and provides support
A barrier through which waste products are filtered from the blood
What are the 3 parts to the ultrafiltration system?
- Fenestration
- The basement membrane
- Podocytes
If particles passes through all 3 parts
They become part of the glomerular filtrate
Explain what fenestration is
Fenestrate = Transparent area
Fenestrations between the cells in the walls of the capillaries
They allow fluid to escape but NOT blood cells
Explain what the basement membrane is and what it is made out of
The basement membrane that covers and supports the wall of the capillaries
It is made of negatively-charged glycoproteins
- Which forms a mesh
It prevents plasma proteins from being filtered out
- Due to their size and negative charges
What are podocytes and what do they form?
Podocytes
- Are highly specialized cells of the kidney glomerulus
- Wraps around capillaries and that neighbor cells of the Bowman’s capsule
- forms the inner wall of the Bowman’s capsule
- Helps prevent small molecules from being filtered out of the blood in the glomerulus
What is the the proximal convoluted tubule and what is its role?
It is the first part of the nephron
It selectively reabsorbs useful substances by active transport
The glomerulus filtrate floes into the proximal convoluted tubule
What are the 4 things that the proximal convoluted tubule absorb and how does it absorb it?
- Sodium ions; By active transport from filtrate to space outside the tubule
- Chloride ions; Attracted form filtrate to space outside the tubule because of charge gradient set up by active transport if the sodium ions
- Glucose; Is co-transported out of filtrate and into fluid outside the tubule
- Water; Pumping salutes out of filtrate and into the fluid outside the tubule creates a solute concentration gradient, causing water to be reabsorbed from filtrate by osmosis
Describe the structure of the proximal convoluted tubule
Outermost layer; The basement layer
- Invaginations (folds) of the outer membrane
Mitochondria near the basement layer
Microvilli surrounding the lining of the tubule wall
Lumen containing filtrate
What is the basic functional unit of the kidney?
The nephron
- A tube with a wall consisting of 1 layer of cells
- The wall is the last layer of cells that substances cross to leave the body, it is an epithelium