Urinary study guide
What causes their release
WHEN THE HEART MUSCLE IS STRETCHED DUE TO TOO MUCH BLOOD VOLUME, ANP AND BNP ARE RELEASED BY HEART INTO THE BLOOD
You do not need to know the specifics of each molecule transported, but is there active transport of substances going on here
YES. MOST OFTEN BY PUMPING MOLECULES, I.E., ACTIVE TRANSPORT. THIS CAN BE EITHER PRIMARY OR SECONDARY ACTIVE TRANSPORT. SOME MOLECLES BY SIMPLE DIFFUSION.
Generally speaking, how much of what gets filtered into the glomerular (Bowman's) capsule gets reabsorbed in the proximal convoluted tubule
60-70% GREATER THAN 99%
What does aldosterone do
ALLOWS FOR THE REABSORPTION OF SODIUM FROM THE DISTAL CONVOLUTED TUBULE AND COLLECTING DUCT INTO THE BLOOD
What is the advantage of a high interstitial fluid concentration gradient in the renal medulla
ALLOWS US TO CONCENTRATE OUR URINE IN THE PRESENCE OF ADH
How does this hormone affect the afferent and efferent arteriole
ANGIOTENSIN II CAUSES MORE CONSTRICTION OF THE EFFERENT ARTERIOLE THAN THE AFFERENT ARTERIOLE, CAUSING AN INCREASE IN GFR
How does this hormone control peripheral resistance
ANGIOTENSIN II IS A POWERFUL VASCOCONSTRICTOR OF SYSTEMIC ARTERIOLES
What is ADH
ANTIDIURETIC HORMONE
What substances can pass from the glomerulus into the Bowman's capsule in a healthy kidney
ANYTHING SMALL: IONS, GLUCOSE, AMINO ACIDS, ETC.
What are the functions of the urinary system
ELIMINATE WASTES, CONTROL VOLUME (BLOOD PRESSURE) AND COMPOSITION OF BODY FLUIDS, PRODUCE RENIN, PRODUCE ERYTHROPOEITIN (RBC FORMATION), METABOLIZE VITAMIN D INTO ACTIVE FORM (CA2+ UPTAKE), STABLIZE BLOOD PH
What substances are secreted in the tubule
K+, H+/HCO3-,UREA, ANTIBIOTICS
What substances cannot pass across the filtration membrane
LARGE PROTEINS, BLOOD CELLS
What causes its release
LOW BLOOD OSMOLARITY DETECTED BY THE HYPOTHALAMUS CAUSES ITS RELEASE AND ANGIOTENSIN II STIMULATES THE HYPOTHALAMUS INCREASE ITS PRODUCTION OF ADH AND IT IS RELEASED FROM THE POSTERIOR PITUITARY
What is the layer deep to that called
MEDULLA
Where does it act
ON THE DCT AND COLLECTING DUCT IN THE NEPHRONS OF THE KIDNEYS
How does the water that is present in the filtrate become reclaimed into the blood
WATER LEAVES TUBULE WHERE IT CAN (LOOP OF HENLE [AND DCT AND COLLECTING DUCT IN PRESENCE OF ADH]) AND MOVES INTO PERITUBULAR CAPILLARIES BY OSMOSIS
What is lost in urine (generally)
WATER, NITROGENOUS WASTES (UREA), IONS, HYDROGEN ION, ORGANIC MOLECULES, DRUGS, TOXINS, ETC.
When are they released
WHEN BLOOD VOLUME AND BLOOD PRESSURE ARE TOO HIGH
Why is our ability to change urine's volume important
BECAUSE WHEN OUR SYSTEMIC BP IS LOW, WE NEED TO CONSERVE OUR BODY'S WATER - BRING MORE WATER INTO THE BLOOD, INCREASING THE BLOOD VOLUME AND INCREASING THE BLOOD PRESSURE, ADH ALLOWS US TO CONSERVE WATER
What makes up the renal corpuscle
GLOMERULAR CAPSULE (BOWMAN'S CAPSULE) AND THE GLOMERULUS
What division of the autonomic nervous system affects GFR
SYMPATHETIC NS
What is the driving force pushing filtrate into the capsule
SYSTEMIC BLOOD PRESSURE
Blood travels through the following vessels in what order (from where blood enters the kidney to where blood leaves the kidney): renal vein, renal artery, afferent arteriole, efferent arteriole, glomerulus, peritubular capillary/vasa recta.
(Drawing this out might be helpful, if that style suits you - I've included the nephron drawing at the end of these questions) RENAL ARTERY - AFFERENT ARTERIOLE - GLOMERULUS - EFFERENT ARTERIOLE - PERITUBULAR CAPILLARY/VASA RECTA -RENAL VEIN
What happens during myogenic control
(you may have answered this above) INCREASED STRETCH OF THE AFFERENT ARTERIOLE CAUSES A DECREASE IN THE AFFERENT ARTERIOLE DIAMETER, REDUCING FLOW & GFR. THIS IS TO PROTECT THE GLOMERULUS FROM DAMAGE THAT WOULD BE CAUSED BY EXCESSIVE HIGH BLOOD PRESSURE. DECREASED STRETCH OF THE AFFERENT ARTERIOLE CAUSES AN INCREASE IN THE AFFERENT ARTERIOLE DIAMETER, INCREASING FLOW & GFR.
What happens during tubuloglomerular feedback
(you may have answered this above) SLOW FLOW/LOW OSMOLARITY GETS DETECTED BY THE MACULA DENSA CELLS OF THE DISTAL CONVOLUTED TUBULE (DCT). THIS CAUSES THE AFFERENT ARTERIOLE TO DILATE INCREASING FLOW & GFR. HIGH FLOW/HIGH OSMOLARITY GETS DETECTED BY THE MACULA DENSA CELLS FO THE DCT. THIS CAUSES THE AFFERENT ARTERIOLE TO CONSTRICT DECREASING FLOW & GFR
Where does it move out of the nephron (from what region of the tubule
)? LOOP OF HENLE (AND DCT AND COLLECTING DUCT IN PRESENCE OF ADH)
How does it function to create a low volume, high concentration urine
ADH ALLOWS FOR THE CONCENTRATION OF URINE BECAUSE IT MOVES WATER OUT OF THE FILTRATE MOVING TOWARD SODIUM ("WATER FOLLOWS SALT") OR OTHER PARTICLES IN THE INTERSTITIAL FLUID. WHEN WATER IS PULLED OUT OF THE FILTRATE BACK INTO THE BLOOD, THE FILTRATE REMAINING BECOMES LOWER IN VOLUME AND MORE CONCENTRATED.
What other hormones are used to increase GFR
ADH AND ALDOSTERONE
Describe how these hormones increase GFR.
ALDOSTERONE CAUSES THE REABSORPTION OF SODIUM IN THE DCT AND COLLECTING DUCT AND ADH CAUSES THE REABSORPTION OF WATER IN THE DCT AND COLLECTING DUCT. THE SODIUM MOVING INTO THE BLOOD CAUSES THE WATER TO FOLLOW IT. THIS INCREASES BLOOD VOLUME AND BLOOD PRESSURE AND AN INCREASE IN SYSTEMIC BLOOD PRESSURE WILL CAUSE AN INCREASE IN GFR
How does it function in urine formation
ALDOSTERONE CHANGES THE CONCENTRATION OF URINE BECAUSE IT MOVES SODIUM OUT OF THE FILTRATE AND IF POSSIBLE, WATER WILL FOLLOW THE SODIUM ("WATER FOLLOWS SALT"). WHEN WATER IS PULLED OUT OF THE FILTRATE BACK INTO THE BLOOD, THE FILTRATE REMAINING BECOMES LOWER IN VOLUME AND MORE CONCENTRATED. ALSO, ALDOSTERONE CAUSES THE SECRETION OF POTASSIUM IF POTASSIUM LEVELS IN THE BODY ARE TOO HIGH.
What causes its release
ANGIOTENSIN II STIMULATES THE ADRENAL CORTEX TO RELEASE ALDOSTERONE
How do they function in urine formation
ANP AND BNP ALLOWS FOR THE PRODUCTION OF A DILUTE URINE BECAUSE ADH AND ALDOSTERONE ARE NO LONGER WORKING AT THE DCT AND COLLECTING DUCT TO REMOVE WATER AND SODIUM FROM THE FILTRATE.
How do they function to create a high volume, low concentration urine
ANP AND BNP ALLOWS FOR THE PRODUCTION OF A DILUTE URINE BECAUSE ADH AND ALDOSTERONE ARE NO LONGER WORKING AT THE DCT AND COLLECTING DUCT TO REMOVE WATER AND SODIUM FROM THE FILTRATE.
What are the natriuretic peptides (ANP/BNP)
ATRIAL NATRIURETIC PEPTIDE (ANP) AND BRAIN NATRIURETIC PEPTIDE (BNP) ARE BOTH RELEASED BY HEART WHEN THE HEART MUSCLE IS STRETCHED DUE TO TOO MUCH BLOOD VOLUME
What are the different ways that the kidney act locally (autoregulation) to maintain GFR
AUTOREGULATION: MYOGENIC CONTROL AND TUBULOGLOMERULAR FEEDBACK
What do they do
BASICALLY, THEY OPPOSE THE ACTIVITY OF ADH, ALDOSTERONE, AND THE RENIN-ANGIOTENSIN SYSTEM. THEY ALLOW WATER AND SODIUM TO BE LOST FROM THE BODY BY LEAVING THEM IN THE FILTRATE (NOT REABSORBING THEM).
Filtrate passes through the following structures in which order (from where filtrate enters nephron to where it exits nephron - not listed in the proper order): glomerulus, distal convoluted tubule, loop of Henle, proximal convoluted tubule, Bowman's capsule, collecting duct.
BOWMAN'S CAPSULE - PROXIMAL CONVOLUTED TUBULE - LOOP OF HENLE -DISTAL CONVOLUTED TUBULE - COLLECTING DUCT
How does Angiotensin II raise the GFR
CAUSES EFFERENT ARTERIOLE VASOCONSTRICTION, SYSTEMIC ARTERIOLE VASOCONSTRICTION (↑ BP), STIMULATES THIRST, STIMULATES THE RELEASE OF ALDOSTERONE, STIMULATES THE RELEASE OF ADH
Urine passes through the following structures in which order on its way to the bladder: renal pelvis, ureter, collecting duct.
COLLECTING DUCT - RENAL PELVIS - URETER
What structures does it pass through
COLLECTING DUCT - RENAL PELVIS - URETER - URINARY BLADDER - URETHRA
What is the superficial layer of the kidney called (layer, not outer covering)
CORTEX
Where does most secretion occur
DISTAL CONVOLUTED TUBULE
In a healthy nephron, which force wins
GLOMERULAR HYDROSTATIC PRESSURE
What are the names of the main components of this structure
GLOMERULUS AND RENAL TUBULE (INDIVIDUAL, SPECIFIC STRUCTURES TO FOLLOW)
Generally speaking, how much of what gets filtered into the glomerular (Bowman's) capsule gets reabsorbed throughout the length of the whole nephron?
GREATER THAN 99%
What type of urine is produced when they are released
HIGH VOLUME, LOW CONCENTRATION
Where do they act
HYPOTHALAMUS (INHIBIT ADH PRODUCTION), ADRENAL CORTEX (INHIBIT ALDOSTERONE PRODUCTION), AND JUXTAGLOMERULAR CELLS OF THE NEPHRONS OF THE KIDNEYS (INHIBIT RENIN PRODUCTION)
How does increased renin in the blood affect GFR
INCREASED RENIN INCREASES THE PRODUCTION OF ANGIOTENSIN II. SEE iii AND iv BELOW FOR HOW THIS WORKS TO INCREASE GFR.
Where does the filtrate go after it leaves the glomerulus
INTO THE BOWMAN'S CAPSULE
What type of urine is produced when it is released
LOW VOLUME, HIGH CONCENTRATION
What substances are reabsorbed and where do they go once they are removed from the tubule
MOST NOTABLY GLUCOSE, AMINO ACIDS, SODIUM, WATER ARE REMOVED FROM THE FILTRATE AND GO DIRECTLY INTO THE PERITUBULAR CAPILLARIES
What is the functional unit of the kidney
NEPHRON
What do we call this net force produced
NET FILTRATION PRESSURE
Does gravity alone allow for its movement through the ureters
NO If not, what aides its passage? PERISTALSIS - WAVE OF MUSCULAR CONTRACTION "PUSHING" FLUID DOWN THE URETERS TOWARD THE BLADDER
Is filtration a selective process
NO, WHATEVER WILL FIT THROUGH THE HOLES WILL BE FILTERED OUT OF THE BLOOD (IF THEY MAKE IT THROUGH ON THAT PASS)
Is the purpose of increased sympathetic activity really ideal for regulating GFR
NO, THE PURPOSE IS PURELY TO INCREASE SYSTEMIC BP IN ORDER TO MAINTAIN SYSTEMIC BLOOD PRESSURE FOR SURVIVAL.
Is this to the kidney's benefit
NO, THIS IS OFTEN TO THE DETRIMENT OF THE KIDNEYS AS CONSTRICING THE AFFERENT ARTERIOLE WILL REDUCE BLOOD FLOW TO THE VERY METABOLICALLY ACTIVE TISSUES OF THE KIDNEY, POTENTIALLY CAUSING CELL DAMAGE/DEATH.
What drives this movement
OSMOSIS
Which division of the nervous system dominates during the micturition reflex
PARASYMPATHETIC NS (CAUSES CONTRACTION OF THE URINARY BLADDER'S DETRUSOR MUSCLE AND RELAXES THE INTERNAL URETHRAL SPHINCTER)
Where does it re-enter the blood
PERITUBULAR CAPILLARIES
Where in the nephron does most reabsorption occur
PROXIMAL CONVOLUTED TUBULE
Where are the kidneys located in the body
RETROPERITONEAL, INFERIOR AND ANTERIOR TO THE RIBS
Describe how these processes can raise GFR and how they can lower GFR.
SEE BELOW
What other type of tissue is found in the muscularis layer of these organs
SMOOTH MUSCLE
When GFR drops, what is the hormonal response
THE KIDNEYS RELEASE THE ENZYME RENIN. RENIN CAUSES A SERIES OF EVENTS ACTIVATING THE HORMONE ANGIOTENSIN II
What hormonal factors affect GFR
THE RENIN-ANGIOTENSIN MECHANISM (ADH & ALDOSTERONE)
What is net filtration pressure
THE SUM OF ALL THE FORCES ACTING AT THE GLOMERULAR CAPILLARY BED TO PRODUCE FILTRATE
What is GFR
THE VOLUME OF FILTRATE MOVED INTO THE BOWMAN'S CAPSULE PER MINUTE
Name all of the hormones that act on the kidney to change urine volume and concentration.
TO DECREASE URINE VOLUME AND INCREASE CONCENTRATION (TO RAISE BV & BP): RENIN, ANGIOTENSIN II, ADH AND ALDOSTERONE. TO INCREASE URINE VOLUME AND DECREASE CONCENTRATION (TO LOWER BV & BP): NATRIURETIC PEPTIDES (ANP & BNP)
Why is secretion into the filtrate necessary
TO REMOVE THINGS THAT DIDN'T GET RANDOMLY FILTERED OUT, BUT YET WE STILL DON'T WANT IN OUR BODIES (DRUGS, K+, H+, ETC.)
What type of tissue lines the lumen of most of the urinary tract
TRANSITIONAL EPITHELIUM
What is micturition
URINATION - EMPTYING BLADDER
How can we use our urine to control blood pH (think in terms of secretion in the DCT)
WE CAN SECRETE EXCESS H+ (AND REABSORB HCO3-) IF WE ARE TOO ACIDIC OR EXCESS HCO3- IF WE ARE TOO BASIC
When is it released
WHEN BLOOD VOLUME AND BLOOD PRESSURE ARE TOO LOW, AND/OR WHEN THE BLOOD OSMOLARITY ("SALTINESS") IS TOO HIGH
When is it released
WHEN BLOOD VOLUME AND BLOOD PRESSURE IS LOW, AND/OR SODIUM LEVELS ARE LOW, AND/OR POTASSIUM LEVELS ARE TOO HIGH
Does the micturition reflex send a signal to the brain (i.e. do you have conscious control over this reflex
)? YES! SOMATIC NERVOUS SYSTEM CAN CAUSE CONTRACTION OF THE EXTERNAL URETHRAL SPHINCTER PREVENTING URINATION UNTIL AN APPROPRIATE PLACE IS REACHED
What does it do
ADH CAUSES THE CELLS OF THE DCT AND COLLECTING DUCT TO PUT AQUAPORINS (WATER PORES) INTO THEIR CELL MEMBRANES. THE WATER CAN THEN MOVE OUT OF THE FILTRATE INTO THE BLOOD DRIVEN BY OSMOSIS
How does it function in urine formation
ADH CHANGES THE CONCENTRATION OF URINE BECAUSE IT MOVES WATER OUT OF THE FILTRATE MOVING TOWARD SODIUM ("WATER FOLLOWS SALT") OR OTHER PARTICLES IN THE INTERSTITIAL FLUID. WHEN WATER IS PULLED OUT OF THE FILTRATE BACK INTO THE BLOOD, THE FILTRATE REMAINING BECOMES LOWER IN VOLUME AND MORE CONCENTRATED.
How does it function to create a low volume, high concentration urine
ALDOSTERONE ALLOWS FOR THE CONCENTRATION OF URINE BECAUSE IT MOVES SODIUM OUT OF THE FILTRATE AND IF POSSIBLE, WATER WILL FOLLOW THE SODIUM ("WATER FOLLOWS SALT"). WHEN WATER IS PULLED OUT OF THE FILTRATE BACK INTO THE BLOOD, THE FILTRATE REMAINING BECOMES LOWER IN VOLUME AND MORE CONCENTRATED.
What does it do
ALDOSTERONE CAUSES THE CELLS OF THE DCT AND COLLECTING DUCT TO PUT SODIUM-POTASSIUM PUMPS AND SODIUM CHANNELS INTO THEIR CELL MEMBRANES. THE SODIUM-POTASSIUM PUMPS MOVE SODIUM OUT OF THE FILTRATE INTO THE BLOOD AND POTASSIUM OUT OF THE BLOOD INTO THE FILTRATE
What are the forces acting to push/pull filtrate back into the glomerulus
PULL INTO THE BOWMAN'S CAPSULE - COLLOID OSMOTIC PRESSURE, PUSH INTO THE BOWMAN'S CAPSULE - CAPSULAR HYDROSTATIC PRESSURE
What are the forces acting to push/pull filtrate into the Bowman's capsule
PUSH INTO THE BOWMAN'S CAPSULE- GLOMERULAR HYDROSTATIC PRESSURE
What ion is the driving force that creates the ability to move many molecules out of the filtrate (glucose, amino acids, etc.)
SODIUM
Which division of the nervous system affords us the ability to urinate at the appropriate place and time (think, conscious control)
SOMATIC NERVOUS SYSTEM
What is reabsorption and how is it done (how do the reabsorbed substances get from the filtrate to the peritubular capillary)
SUBSTANCES IMPORTANT FOR THE BODY ARE REMOVED FROM TUBULE FILTRATE AND BROUGHT BACK INTO THE BODY (BLOODSTREAM). SUBTANCES ARE TRANSPORTED ACROSS APICAL CELL MEMBRANE AND THEN BASAL CELL MEMBRANE AND THEN INTO THE BLOOD.
Which division of the nervous system dominates during urine storage
SYMPATHETIC NS (INHIBITS URINARY BLADDER'S DETRUSOR MUSCLE CONTRACTION AND INHIBITS THE INTERNAL URETHRAL SPHINCTER RELAXATION)
How does this affect GFR
SYMPATHETIC NS STIMULATION TO THE KIDNEYS CAUSES CONSTRICTION OF THE AFFERENT ARTERIOLE. CONSTRICING THE AFFERENT ARTERIOLE REDUCES BLOOD FLOW INTO THE GLOMERULUS AND THEREFORE DECREASES GFR
Describe the process of glomerular filtration.
SYSTEMIC BLOOD PRESSURE IS CREATED BY THE HEART FORCING BLOOD THROUGH THE VESSELS OF THE BODY, INCLUDING THE AFFERENT ARTERIOLES AND GLOMERULI. THIS BP (GLOMERULAR HYDROSTATIC PRESSURE) "PUSHES" FLUID AND SMALL PARTICLES THROUGH THE SIMPLE FILTER THAT IS THE GLOMERULUS. THE "PUSH" CREATED BY THE SYSTEMIC BP IS OPPOSED BY 2 FORCES, THE PRESSURE EXERTED BY THE FLUID IN IN THE BOWMAN'S CAPSULE (CAPSULAR HYDROSTATIC PRESSURE) AND THE PRESSURE EXERTED BY THE PROTEINS IN THE GLOMERULUS (COLLOID OSMOTIC PRESSURE). AT TYPICAL SYSTEMIC BP'S, THE GLOMERULAR HYDROSTATIC PRESSURE "WINS" FORCING FLUID OUT OF THE GLOMERULUS, BUT IF THE SYSTEMIC BLOOD PRESSURE DROPS EVEN 15%, FILTRATE PRODUCTION STOPS!
Describe the process of hormonal regulation of GFR.
WHEN SYSTEMIC LOOD PRESSURE AND/OR BLOOD VOLUME DROPS, THE KIDNEYS DETECT THIS AND RELEASE THE ENZYME RENIN. RENIN CAUSES THE PRODUCTION OF ANGIOTENSIN II. ANGIOTENSIN II CAUSES VASOCONSTRICTION OF SYSTEMIC ARTERIOLES, RAISING SYSTEMIC BP, RAISING GFR. ANGIOTENSIN II ALSO VASOCONSTRICTS THE EFFERENT ARTERIOLE, CAUSING MORE FLUID TO LEAVE THE GLOMERULUS, RAISING THE GFR. ALSO, ANGIOTENSIN II CAUSES THE RELEASE OF ADH AND ALDOSTERONE WHICH CAUSE THE REABSORPTION OF WATER AND SODIUM (RESPECTIVELY), CAUSING AN INCREASE IN BV, AN INCREASE IN BP, AND THEREFORE AN INCREASE IN GFR.
