Lecture 51- Urinary System Part 2 Flashcards
Glomerular Filtration Rate
Tubular reabsorption
Tubular secretion
What are the four carrier-mediated transport mechanisms
- Facilitated diffusion
- Active transport
- Co-transport
- Counter transport
What is facilitated diffusion
-Carrier transport
-No ATP required down the gradient
What is active transport?
Substances moved against concentration gradient
Requires ATP
What is co-transport?
Does not require ATP
2 substances moved in same direction
What is counter transport?
Similar to co-transport but move in opposite directions
Transport maximum
The point where increasing substrate concentration will not increase transport because carriers are saturated
Where do saturated excess substances end up?
Cannot be reabsorbed and is excreted and starts spilling substances into URINE
What type of fluid does the transport occur in?
Tubular fluid is formed from Glomerular filtration
What is the descending limb of the nephron loop only permeable to?
Water
What is the ascending limb of the nephron loop only permeable to?
Solute
How does the concentration change as filtrate moves down the descending limb?
Increases
Removing water
How does the concentration change as filtrate moves up the ascending limb?
Decreases
Removing ions
Countercurrent multiplcation
The flow of filtrate happens in opposite direction in nephron loop (down VS up)
Change in concentration is multiplied from cortex to medulla (increase VS decrease)
How is the osmotic gradient established in the peritubular fluid?
Different mechanism
What is the main solute to consider in the peritubular fluid?
Urea
How does urea concentration change as the filtrate moves from the nephron loop to the conducting duct
Increases
This section is impermeable to urea, so filtrate can’t leave
What duct is permeable to urea?
Papillary duct
What is the role of the vasa recta?
Vasa recta help to prevent excessive loss of water and electrolytes in the urine, thereby helping to maintain proper fluid balance in the body
What are the three ways to control glomerular filtration rate?
- Autoregulation
- Neural (autonomic regulation)
- Hormonal regulation
Autoregulation
Dominant regulation at rest
Neural (autonomic regulation)
Activated under stress/physical activity
Constricts afferent arteriole
Hormonal regulation
Initiate by kidneys/uses aldosterone system
What makes up the juxtaglomerular complex?
- Juxtaglomerular cells
- Macula densa
- Mesangial cells
Juxtaglomerular cells
Smooth muscle cells in walls of afferent arteriole
(Mechanoreceptors)
Macula densa
Tall closely packed distal tubule cells
(Chemoreceptors or osmoreceptors)
Mesanglial cells
Phagocytic and contractile properties
What three things happen to increase GFR after a drop has been detected, leading to decreased filtrate and urine production?
- Dilation of afferent arterioles
- Contraction of mesangial cells
- Constriction of efferent arterioles
Neural stimuli effects
- Increased heart rate/blood pressure/metabolic rate
Hormonal stimuli effects
- Cortisol trigger
- Aldosterone will trigger
