EXAM 2- Kidneys Flashcards
What are the 2 major active membrane transport processes
Active and Vesticular transport
Why does both VT and AT require ATP to move solutes across a plasma membrane
Solute too large for channels, Solute is not lipid soluble, or solute os not able to move down a concentration gradient
What are the three types of diffusion
Simple, facilitated, osmosis
How much ATP is used in the kidney daily
30-35%
What does it mean when blood osmolarity decreases
you have too much water (Overhydrated), you pee more to save salts
What does it mean when blood osmolarity increases
you have not enough water (dehydrated), you pee less H2O to rid salts
What is an antiporter
transport 1 substance into cell while transporting a different substance out of the cell while transporting a different substance out of the cell
What is are symporters
transport 2 different substances in the same direction
What is primary AT
required energy comes directly from ATP hydrolysis, which causes a shape change of transport protein
What is secondary AT
Required energy is obtained indirectly from ionic gradients created by primary active transport
What are leakage channels
Located in the membrane, results in leaking of Na+ into the cell and K+ out of cells
Are sodium-pot pumps antiporters or symporters
Antiporter, Na out of cell and K into cells, against their respective gradients
Why are there leakage channels
Because the membrane is selectively permeable, so the Na and K leak back in/out
What is the ratio of Sodium and Potassium
3:2
Vesticular transport
Involves transport of large particles, marcomolecules and fluids across the membrane in membranous sacs (vesicles)
Does vesticular transport require ATP
Yes! cellular energy, typically ATP
What does the vesticular transport process include
Endocytosis, Exocytosis, Transcytosis
Endocytosis
- Transport into cell (cytoplasm)
- Involves formation of protein coated vesicles
- Involves receptors
- When the vesicle is pulled into cell it can fuse with lysosome or undergo transcytosis
- Some pathogens can hijack receptors for transport into cell
What are the three types of endocytosis
Phagocytosis, Pinocytosis, Receptor mediated endocytosis
Exocytosis
transports out of cell (cytoplasm)
- Process where material is ejected from cell
- Ejected material en enclosed in secretory vesicle
Transcytosis
Transport into, across and out of cell (Cell highway)
What is phagocytosis
The cell engulfs a large particle by forming a projected psudeopod around it. Encloses it within a phagosome.
- Phagosome combines with a lysosome and digests contents
In phagocytosis what are the vesicle receptors capable of binding too?
Microorganisms or solid particles
What is Pinocytosis
- Cells gulp a drop of extracellular fluid containing solutes into tiny vesicles.
- No receptors are used, non-specific process
- Main way for nutrient absorption in small intestine
- Membrane components are recycled into membrane
What type of endocytosis is referred to as cell drinking or fluid phase endocytosis
Pinocytosis!
What is Receptor mediated endocytosis?
- Involves endocytosis and transcytosis of specific molecules
- Many cells have receptors embedded in clathrin-coated pits. To be internalized along with specific molecules bound
In Receptor mediated endocytosis what do extracellular substances bind to?
Specific Receptor proteins, that enable the cell to ingest and concentrate specific substances in protein coated vesicles. The substances can be released inside the cell or digested in a lysosome
What activates exocytosis
Cell surface signals or changes in membrane voltage
What are the proteins on vesicles for exocytosis
V-SNARE finds and hooks to target T-SNARE proteins on membrane
What trigers endocytosis
Docking process (V/T-SNARES)
What are examples of substances to be exocytosed?
Hormones, neurotransmitters, mucus, cell wastes
What is the process of exocytosis
- Membrane bound vesicles migrates to plasma membrane
- There, Proteins at the vesicle surface (V-SNARES) bind with T-SNARES
- Vesicle and plasma membrane fuse and a pore opens up
- Vesicle contents are released to cell exterior
What is the process of Docking
When the Vesicle and plasma membrane fuse and a pore opens up
What is true urine
urine that is fully formed
Where does formative urine go to become urine
leave the kidneys
Why would you take a diuretic drug?
With high BP, to pee more because you have excess blood volume you need to rid. The Diuretic drug reduces BV which reduces BP
What is an Anti-diuretic?
Drug that makes you conserve water, pee less. For when you are dehydrated
What is creatine
byproduct of muscle contraction
What creates a hyperotnic solution
Too much urea
Renal control of electrolyte balance
Sodium, Magnesium, Zinc, Iron
Renal control of Acid-Base Balance
too many protons, kidneys flush them out
Urinary System Organs
Urinary Bladder, Paired Ureters, and urethra
Urinary Bladder
Provides a temporary storage reservoir for urine
Paired Ureters
transport urine from kidneys to bladder
Urethra
transports urine from bladder out of body
How many gallons of blood is filtered daily
180 Liters (45 gallons)
What are the functions of the Kidneys
- Filter blood, allows toxins, metabolic wastes and excess ions to leave body in urine
- Regulate volume and chemical makeup of blood
- Maintain proper balance of water/salts and acids/bases
What are the mechanisms of Urine Formation
- Glomerular Filtration
- Tubular Absorption
- Secretion
Filtration Membrane
- Entry points of bowman’s capsule has filtration slits
- Fenestrations don’t allow blood through, only h2o and glucose and cells
What are fenestrated Capillaries
- Found where active capilary absorption or filtrate formation occurs (small intest., endocrine glands, kidneys)
What are fenestrated Capillaries characterized by
- An endothelium riddled with pores
- Greater permeability to solutes and fluids then other capillaries
Golmerular Filtration
- Principles of fluid dynamics that account for tissue fluid in all capillary beds apply to the glomerulus as well
Why are glomerulus beds more efficient than other capillary beds?
- Filtration membrane is significantly more permeable
- Glomerulus BP is higher
- Has higher Net Filtration Pressure
- Plasma proteins are not filtered, and used to maintain osmotic pressure of blood
What is blood filtered by
Hydrostatic pressure
What would an increase in blood pressure do
What effect would this have on urine production
What is the total amount of filtrate formed per minute by the kidneys
Men: ~ 125ml/min
Female: ~120ml/min
This is GFR
How often does blood volume get filtered into glomerulus to bowman’s capsule?
Every 40 minutes
What needs to be reabosrbed in Bowman’s Capsule
Water, salts, glucose
How much of formative urine (Filtrate) is resbsorbed?
about 99%
GFR is directly proportional to what?
Net filtration pressure
What happens if GFR is too high
Needed substances cannot be reabsorbed quickly enough and are lost in the urine
What happens if GFR is too low
Everything is reabsorbed, including wastes that should be disposed of
What are 3 mechanisms that control GFR
- Renal Autoregulation (intrinsic Systems)
- Neural Controls
- Hormal Mechanism (RAAA)
What happens when you fail to regulate BP
high BP= blood in urine
low BP= Urine in blood
Low BP is vaso..
dilation
High BP is vaso…
constriction
Under normal conditions renal autoregulation maintains what
a nearly constant GFR
When does Juxtaglomerular apparatus (JGA) (Intrinsic 2) kick in
When GFR is high and intrsinic 1 is active but can’t do enough to regulate GFR
What is Tubular glomerular (JGA) (Intrinsic 2)
Involves Juxtaglomerular apparatus (Macula densa cells) and the distal loop of henle
What are extrinsic controls under stress
- Norepinephrine/epi is released by SNS
- Epi is released by adrenal medulla
- Afferent Arterioles constrict and filtration is inhibited
When is renin released
With a dramatic drop in blood pressure
What triggers renin release
- Reduced stretch of granular JG cells
- Direct stimulation of the granular JG cells via norepinephrine/epi by renal nerves
*the pressure reducing causes the cells to act
Where does angiotensinogen II travel to become angiotensinogen II
travels in blood to the lungs
What are the actions of angiotensinogen II
- Vasoconstriction of systemic arterioles (Increased BP)
- Stimulates Aldosterone secretion from adrenal cortex
- Stimulation of thirst centers in Hypothalamus
- Stimulation of ADH from posterior pituitary gland
What does aldosterone stimulate
Increases sodium, chloride and water by the kidneys, leading to increase in BV and BP
*pee less
What does water renention by the kidneys from ADH do
Makes DCT and collecting ducts more permeable to water (increase BV and BP)
What is released for High blood pressure
Atrial Natiuretic Peptide (ANP)
In response to high blood pressure..
- Dilates Afferent Arterioles (increase GFR)
- Increases permeability of glomerulus (increase GFR)
- ADH release shuts off
- Decrease in Aldosterone and Renin, both not released with high BP
In response to low blood pressure…
- Constricts Afferent Arterioles (decrease GFR)
- Decreases permeability of glomerulus (decrease GFR)
- ADH release decreases
- Decrease in Aldosterone and Renin
Proximal Convoluted Tubule
- Site of reabsorption
- All nutrients, such as a glucose and amino acids, sodium, water and major ions are reabsorbed
- 65% of Na+ and water reabsorbed
- Lots of Active transport occuring
Why do the kidneys have mitochondria
as fast as the kidneys make ATP they are using it to get all filtered stuff back into the blood
Transport maximum
Tm exists for almost every reabsorbed substance
- Reflects the number of carriers in renal tubules that are available, when there’s excess solutes they are secreted in urine
Transcellular transport systems are..
specific and limited
Osmolarity
The number of solute particles dissolved in 1 liter of water
What keeps the solute load of bodily fluids constant at 300 mosm
the kidneys accompanied by the countercurrent mechanism system
Countercurrent mechanism
Interaction between the flow of filtrate through the loops of henle and the flow of blood through the vaso recta
Loop of Henle Descending loop for countercurrent multiplyer
Reletivley impermeable to solutes but permeable to water
Loop of Henle Ascending loop for countercurrent multiplyer
permeable to solutes but impermeable to water
What is renal clearance
The volume of plasma that is cleared of a particular substance in given time
What do renal clearance tests determine
GFR
detect glomerular damage
follow progress of existing renal disease
What is inulin
A substance that cannot be broken down
so all inulin that comes in all comes out
What is chronic renal disease
defined as GFR< 60ml/min for 3 months
what occurs when GFR< 60ml/min for 3 months
the filtrate formation decreases, nitrogenous wastes accumulate in blood, pH becomes acidic
Define renal failure
when GFR <15ml/min
What makes urine yellow
urochrome
What can indicate bacterial infection in urine
cloudy urine
What can change the color of urine
- drugs
- vitamin C supplements
- Diet
Odor in urine
- Fresh urine smells a little
- Standing urine develops ammonia odor
- Drugs and foods can alter the smell of urine
What is specific gracity
Ranges from 1.001 (dilute)- 1.035 (concentrated)
- Higher value, more salts
- Dependent on solute concentration
What is the chemical composition of urine
95% water
5% solutes
Nitrogenous Wastes in urine
- Urea: From AA breakdown (largest solute componet)
- Uric acid: From nucleic acid metabolism
- Creatinine (metabolite of creatine phosphate)
What does GFR match in the blood
creatinine
What can be used to measure kidney health if patient is allergic to inulin
Inject Creatinine
