Exam 4 Flashcards
What are the two types of substances removed?
- By-products of metabolism
– Creatinine from muscle metabolism
– Urea from amino acids - Foreign substances, such as drugs
environmental toxins
– Saccharin in artificial sweetener
– Benzoate in diet soda
What is gluconeogenesis?
In times of starvation we convert fat into glucose
Why do we have a high rate of kidney flow?
To maintain fluid and electrolyte levels that are important to heart health
What is filtration driven by?
Pressure system. Selects based on size
What is a nephron?
The structural and
functional units that form urine.
What is secretion?
Selectively moving things out of the blood and into the tubule.
What is the equation for urinary clearance?
Excretion = Filtration - Absorbance + Secretion
aka
E = F - R + S
Where is the cortex?
It is surrounding the kidney
Is the glomerulus high or low pressure?
It is high pressure
What are the 2 types of nephrons?
Cortical nephrons and juxtamedullary nephrons
What is filtered in the glomerulus?
Plasma
What does the glomerular capsule do?
It collects the filtrate
What is wrapped around the capillaries in the glomerulus?
Podocytes
What is the function of podocytes?
Wraps around capillaries so they don’t break apart in the high pressure environment
T or F
Capillaries are leaky.
True!
How do capillaries regulate filtration?
They are leaky, but the holes are fairly small, so size is the only regulation, anything in the plasma that is smaller than a protein will end up in filtrate
What happens in the proximal convoluted tubule?
Reabsorption- taking back what we want to keep
What happens in the nephron loop?
Reabsorption of water and salt
What is reabsorption in the distal convoluted tubule and collecting duct regulated by?
Regulated by hormones
What is Glomerular filtration rate?
GFR is blood flow coming into the glomerular through the afferent. The amount of filtrate we’re making over time.
What is the most driving force of GFR?
Blood pressure, which is really high inside the glomerular.
What is the relationship between BP and GFR?
Directly related, if BP goes up, then GFR goes up.
How is GFR affected by exercise?
GFR increases during exercise because BP goes up.
What is the effect of a constantly increased GFR?
If we increase GFR for too long we won’t be able to keep all the correct nutrients and things we don’t want to lose. Think of chronic high blood pressure.
How do we change the pressure in GFR?
Myogenic controls, which is changing the sizes of the afferent and efferent arteries.
What happens to Glomerular filtration rate if BP goes up?
GFR goes up. We constrict the afferent artery to decrease blood flow into glomerulus to decrease the pressure. Then dilate efferent to also reduce pressure inside.
What happens with myogenic controls when BP goes down?
Efferent is constricted to keep the pressure up so GFR doesn’t go down.
What are the 3 mechanisms to control the GFR?
Myogenic control, JG cells, macula densa cells.
What is the renin pathway?
Renin is released from JG cells.
In the liver, angiotensinogen is converted to angiotensin 1 which enters the blood.
In the bloodstream, ACE converts angiotensin 1 into angiotensin 2 which has 2 effects.
Angiotensin 2 constricts all of the arterioles which directly increase BP. 2nd effect is the angiotensin 2 goes to the adrenal cortex and triggers the release of hormone aldosterone.
Aldosterone goes back to the kidney and increases sodium reabsorption in the CD/DCT. This increase water reabsorption which increases BV and therefor increases BP.
Explain ADH stimulus, sensor, type of receptor, and effector.
Stimulus for ADH release is an increase in the osmolarity of the blood (can happen from too much salt or dehydration). The hypothalamus is what detects this shift. Then, hypothalamus increases ADH output, which increases the number of aquaporins in the CD/DCT to increase water reabsorption. The hypothalamus also increases the thirst drive. Urine output decreases.
Explain ANP stimulus, sensor, type of receptor, and effector.
Stimulus for ANP is an increase in blood pressure, then it inhibits renin. Urine production goes up because we don’t reabsorb salt as much, so water doesn’t move out. Traps sodium in the filtrate to hold water and increase urine output which decreases blood volume and decreases blood pressure.
Explain Renin stimulus, sensor, type of receptor, and effector.
Stimulus for renin/aldo is decrease in BP. The JG cells are the sensor. They are mechanoreceptors. Response is constriction of arterioles and release of hormone aldo which increases sodium reabsorption in CD/DCT
How is salt reabsorbed?
By sodium potassium pump using active transport by ATP
How is water reabsorbed?
By osmosis through aquaporins by following salt.
How much glucose is reabsorbed?
100%
What is the purpose of the loop of henle?
For reabsorption of water and salt. Concentrates urine and saves as much water as possible.
What happens in the descending limb in the loop of henle?
The descending limb is permeable to water and impermeable to salts. Water moves through aquaporins. Gets much saltier the further along it travels.
What happens in the ascending limb?
Ascending limb is impermeable to water and actively pumps salt out. No aquaporins on this side.
How much nutrients get reabsorbed in the PCT?
100%
Why would there be glucose in the urine?
Transport maximum is exceeded with diabetes and why there is glucose in the urine
What is a reason someone with diabetes would be dehydrated?
In diabetes, excess glucose in filtrate makes water not absorb as much because it follows concentrate
What happens in the distal convoluted tube?
Not leaky, only reabsorbs regulated things. Functions more in secretion than reabsorption
What happens in Collecting Duct?
Fully regulated by hormones ADH and Aldo. Anything that makes it past the CD is now urine, no longer filtrate.
T/F
Urine will be less salty when aldo increases?
True! Increase of aldo = increase in salt reabsorption which will make the urine less salty.
What is renal clearence?
Renal clearance is how effective the kidneys are at ridding waste from the body.
What is the composition of urine?
95% water and 5% solute
What are two indicators in the urine of urinary infection?
Cloudy or odor of ammonia
What is insensible losses of water?
Water loss from breathing
What are electrolytes?
Charged molecules
What is hyponatremia?
Too low sodium
What is hypercalcemia?
Too high calcium
What is hypokalemia?
Too low potassium
What are two purposes of electrolytes?
Cofactors to make the cells run more efficiently
Set up electrochemical gradients
What is the significance of using mEq/L as units?
Figures out it’s osmotic influence, aka how much water wants to stick to it
What is renin/aldo stimulus, sensor, receptor type, and response?
Stimulus/variable- Low BP
Sensor/integration center- JG cells
Type of receptor- barrow/mechanical/stretch receptors
Effector/response- increase in BP
What is ADH stimulus, sensor, receptor type, and response?
Stimulus/variable- dehydration
Sensor/integration center- hypothalamus
Type of receptor- chemo receptors
Effector/response- decreased urine output
What is ANP stimulus, sensor, receptor type, and response?
Stimulus/variable- high BP
Sensor/integration center- cardiac muscle
Type of receptor- stretch receptors
Effector/response- inhibited renin, so BP decrease
What regulates potassium and where is potassium found?
Regulated by aldosterone
Found mostly in the cells
What does inhibiting renin do to the sodium levels in the blood?
Inhibiting renin decreases sodium levels in the blood
Why is shift in pH unsafe/fatal?
Proteins give cells their functions
Shifting pH destroys protein shapes/denatures proteins. When proteins die, the cell fails.
Shifts in pH are also shifts in potassium which throws off electrogradients
What is the role of calcium?
Really important for blood clotting, neurotransmission, contracting muscles
What happens when blood calcium levels are high?
When blood calcium levels are high, picked up by the thyroid, releases hormone calcitonin, calcitonin goes to bones and increases osteoblast activity, adding calcium to bone matrix. Extra calcium in the system = store it in the bones.
What happens when blood calcium levels are too low?
Too little calcium, parathyroid release parathyroid hormone (PTH) which stimulates osteoclast cells which break down the bone matrix to release calcium into the blood to bring those levels back up. Parathyroid also stimulates kidneys and stomach to increase reabsorption, bringing calcium absorption back up.
What are the three systems we have in place to handle shifts in pH?
Chemical buffer systems, respiratory center in the brain stem, and renal mechanisms
What is the most common cause of acid-base imbalance?
Respiratory acidosis like fentanyl overdose, pneumonia, and cystic fibrosis
What is a common result of hyperventilation?
Respiratory alkalosis
What is a shift in pH not related to CO2 called?
Metabolic acidosis/alkalosis
What causes metabolic alkalosis?
Vomiting and antacids
What would someone with alkalosis experience with their breathing?
Hypoventilation
What is normal pH?
7.35-7.45
What is expected Na in blood?
135-145
What is expected K in blood?
3.5-5.5
What is expected Calcium in blood?
8.5-10.5
What is the juxtamal apparatus?
Where the plasma passes the efferent and afferent arteries. The special structure found there is Macula densa cells
What is micturition?
The act of peeing
Why is urine a good diagnostic tool?
Urine is a good diagnostic tool because it is noninvasive, you can get a snapshot of the health of the kidneys and the liver. PH and glucose give endocrine feedback
What is calcium balance controlled by?
PTH and calcitonin
What is the only organ in the body that can get rid of fixed acids?
Kidneys
What is the correct sequence of organs for the formation and elimination of urine?
Kidney, ureter, bladder, urethra
Which is not a function of the kidneys?
A. Regulation of blood pressure
B. Removal of wastes from the blood
C. Regulation of erythrocyte production
D. Regulation of lymphocyte production
E. Regulation of acid-base balance
D- regulation of lymphocyte production
Where are the renal pyramids located within the kidney?
Renal medulla
The thick tangle of capillary loops found within a cortex is known as what?
Glomerulus
The proximal convoluted tubule is lined with what type of cell and why?
Cuboidal epithelium with a large surface area.
Which class of nephron is crucially important in establishing a salt concentration gradient in
the kidney so that urine concentration can be regulated?
Juxtamedullary nephrons
Where is the juxtaglomerular apparatus located?
Near the vascular pole of the renal corpuscle
What are the main parts of the juxtaglomerular apparatus?
JG cells and macula densa
Stimulation of granular cells by the sympathetic nervous system causes them to do what?
Contract
Macula densa cells monitor the concentration of what?
Sodium chloride in the fluid within the distal convoluted tubule.
The capillaries of the glomerulus differ from most other capillary networks in the body
because they…
Drain into an arteriole instead of a venule
What is the correct order for the process of urine formation?
Capsular space of glomerulus
Nephron loop
Collecting duct
Distal convoluted tubule
Proximal convoluted tubule
Capsular space of glomerulus
Proximal convoluted tubule
Nephron loop
Distal convoluted tubule
Collecting duct
What steps in the process of urine formation occur in the renal tubule?
Secretion and reabsorption only
Glomerular hydrostatic pressure is the pressure of what?
Blood in the glomerular capillaries
What fraction of our total fluid is in our cells and what fraction is outside our cells?
2/3 of total fluid is WITHIN cells and 1/3 of total fluid is OUTSIDE cells
When compared to extracellular fluid, intracellular fluid contains…
More potassium and more negatively charged proteins
Drinking a liter of water will cause the osmolarity of blood plasma to increase or decrease?
Decrease
If someone runs a marathon through a desert while eating pretzels and not drinking water,
what happens to their plasma osmolarity?
Osmolarity rises and becomes hypertonic to the interstitial and intracellular fluid compartments
Water lost through shitting is considered what type of water loss?
Sensible and obligatory
What is facultative water loss?
Controlled water loss by hormone effects on the kidney.
What does the hormone ANP do to urine output and blood volume?
Increases urine output and decreases blood volume
What is the most abundant cation within cells?
Potassium
What does angiotensin 2 trigger?
Vasoconstriction and increased urine output from the kidneys
What does aldosterone cause kidney tubules to do?
Reabsorb more sodium and water, secrete more potassium
If someone begins to hyperventilate due to anxiety, the CO2 concentration in their blood
decreases; this causes __________ in blood pH.
An increase
If an individual’s respiratory rate decreases what happens to blood CO2 levels, blood H+ levels, and blood pH levels?
CO2 levels rise, blood H+ levels rise, and blood pH falls.
