Chapter 9.2 Flashcards
Where are the upper portions of each nephron located?
The renal correct of the kidney
Where are the lower portions of each nephron on located?
The renal medulla of the kidney
What are the nephrons surrounded by?
Tissues of the medulla and the cortex
Where do any substances that are secretes by nephrons go?
They are absorbed by the surrounding tissues of the kidney and return to the bloodstream or turn into urine
What 4 processes are crucial to the formation of urine?
Glomerular Filtration
Tubular Filtration
Tubular Secretion
Water Reabsorption
What does Glomerular Filtration do?
Moves water and solutes (except proteins) from blood plasma into the nephron. This is called filtrate
What does tubular reabsorption do?
Removes useful substances such as sodium from the filtrate and returns them into the blood for reuse by body systems
What does tubular secretion do?
Moves additional wastes and excess substances from the blood into the filtrate
What happens in water reabsorption?
Removes water from the filtrate and returns it to the blood for reuse by body symptoms
What process does the formation of urine start with?
Glomerular filtration
What does glomerular filtration do?
Forces the water and dissolved substances in plasma from the glomerulus into the bowman’s capsule
What 2 factors contribute to glomerular filtration?
Permeability of the glomerular and capillaries
Blood pressure
What is special about capillaries in the glomerulus?
They have many pores in their walls large enough to allow things to pass through and into the bowman’s capsule. They are also small enough to prevent blood and proteins from exiting
What is BP like in the glomerulus?
About 4x greater than capillaries elsewhere in the body`
Why is BP high in the glomerulus?
Because it provides the force for filtration
What is the composition of filtrate from the glomerulus to the plasma?
It is essentially plasma without the proteins and blood cells
Where does the filtrate go after it reaches the glomerulus?
The proximal tube
What happens as much of the filtrate enters the proximal tube?
About 65% is reabsorbed and returned to the body
Through what is means is much of the filtrate absorbed from the proximal tubule?
Through passive and active transport
What are the cells of the proximal tubule lined with?
Mitochondria
What does the mitochondria in the proximal tubule do?
They use the power of ATP to drive the active transport of sodium ions, glucose, and other solutes back into the blood
What else is reabsorbed into the bloodstream in the proximal tubule, besides salt?
Negatively charged ions tag along passively and water follows by osmosis
What is the function of the loop of henle?
Reabsorb water and ions from the glomerular filtrate
What does the loop of henle encounter when it descends?
An increasingly salty environment
What are the cells of the descending Henle permeable to?
Water and slightly permeable to ions
How does water diffuse from the loop of Henle?
Because the environment within is so salty, water diffuses from the filtrate and into capillaries
What happens after water diffuses by osmosis from the loop of Henle?
The concentration sodium ions increases, reaching the max
What happens as the very concentrated filtrate continues along the loop of Henle?
It moves into the ascending limb and the permeability changes
What is the permeability of the ascending loop of Henle like?
It becomes impermeable to water and slightly permeable to solutes. Causing sodium ions to diffuse into blood vessels
What happens in the thick walled portion of the loop of Henle?
Sodium ions are moved out of the filtrate by active transport
What are the consequences of moving the sodium ions out of the thick portion of the ascending henle?
- Helps to replenish the salty environment of the medulla
- Makes the filtrate less concentrated than tissue and blood in the surrounding cortex
How does the removal of salt in the thick portion of the Henle help?
It helps to aid in the replenishment of the salt of the medulla
What does the active transport of sodium ions from filtrate and into the capillaries depend on?
The needs of the body
What does passive reabsorption of negative ions occur by?
Electrical attraction
What does the reabsorption of ions do to the filtrate?
Decreases the concentration of the filtrate allowing water to be reabsorbed into capillaries by osmosis
What is secreted into the distal tube?
Potassium ions and hydrogen ions from the bloodstream in capillaries
Why are hydrogen ions secreted into the distal tubule?
To maintain the pH of the blood
What does the filtrate entering the collecting duct contain a lot of?
Water
What happens as a result of the collecting duct extending deep into the medulla?
The concentration of ions along its length increases
What is the concentration of ions along the collecting duct a result of?
The active transport of ions from the ascending limb of the loop of Henle
What does the high concentration of ions in the collecting duct do?
It causes the passive reabsorption of water from filtrate by osmosis
What happens to permeability in the distal tubule if a person is dehydrated?
The permeability to water in the distal tubule is and the collecting duct is increased. Causing more water to be reabsorbed into surrounding capillaries
What does the reabsorption of water in the collecting duct cause?
The filtrate to become 4x as concentrated
