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A&P 20 Exam 3 Questions
If the osmotic pressure of the blood were increased above normal levels, which of the following
volumes would also increase? - correct answer - blood volume
- The higher osmotic pressure in the blood would draw water from the interstitial fluid, resulting in a higher blood volume and increased blood hydrostatic pressure.
osmotic and hydrostatic forces - correct answer - regulate movement of fluids between
compartments
nephron - correct answer - structural and functional unit of the kidneys
- multiple nephrons empty into one collecting duct and each renal pyramid will have many collecting ducts
- consists of two parts
- renal corpuscle: responsible for filtering the blood and forming "pre-urine"
- renal tubule: adjusts contents of pre-urine to for urine. Long length increases processing capability
- removes 99% of water and returns it to the blood
- concentrates urine
- adjusts ion levels
- adjusts pH
cortical nephron - correct answer - form the majority of nephrons in the kidney.
- have most of their structure located within the cortex.
- short nephron loop.
- Cortical nephrons have a short nephron loop that dips into the medulla but is not wrapped in vasa recta.
- Absorption of materials from these nephrons happens in the proximal and distal tubules via the peritubular capillaries.
distal tubule - correct answer - absorption and secretion
- Anti-diuretic hormone (ADH) and aldosterone increase reabsorption of water in the distal tubule
Which of the following would be a "potassium sparing diuretic," a drug that causes an increase in water loss, and a decrease in potassium loss in the kidneys? If you need help, check the hint. -
correct answer A DRUG THAT BLOCKS ALDESTERONE
juxtamedullary nephrons - correct answer - have long loops of Henle that dip deep into the medulla
- located close to the cortex-medulla junction (near medulla). - play an important role in the kidney's ability to produce concentrated urine. They have long nephron loops that deeply invade the medulla.
calyces - correct answer - funnel final urine from collecting ducts towards renal pelvis
- Urine drains continuously from papilla of renal pyramids and empties into a minor calyx
- Several minor calyces drain into a major calyx
- 3-5 major calyces drain into the renal pelvis
- Urine leaves the kidney at the point where the renal pelvis becomes the ureter •Describe the relative volume and solute composition of the fluid compartments of the body -
correct answer - intracellular fluid (2/3): all fluid within body cells
- extracellular fluid (1/3): divided into plasma and interstitial fluid
- all body fluids consist of solvent and solutes: electrolytes, nonelectrolytes
Body fluids - correct answer - consist of solvent and solutes
- solutes: electrolytes or nonelectrolytes
electrolytes - correct answer - dissociate into ions in the water
- ions are charged and can conducts electricity- salts, acids, bases, some proteins
- unevenly distributed between plasma, interstitial fluid and intracellular fluid
nonelectrolytes - correct answer - formed by covalent bonds
- don't dissociate
- not charged
- glucose, lipids, urea, creatine)
- does not conduct electrical current
•Describe the major functions of the kidney - correct answer - regulates total volume of water in
the body and total concentration of solutes
- filters blood and forms urine
- regulates the concentration of ions in the extracellular fluids
- regulate long term acid-base balance
- excrete metabolic wastes and foreign substances
- producing hormones
- converting vitamin D to its active form
Kidney terminology - correct answer - urinary: organ system responsible for water, electrolyte and
acid-base balance, removal of nitrogenous wastes, urine production and excretion
- renal: of or related to the kidneys
- nephro-: of or related to the kidneys
Urinary system organs - correct answer - kidneys: filters blood and forms urine
- ureters: long muscular tubes that transport urine from kidney to urinary bladder
- urinary bladder: muscular organ that stores urine
- urethra: tube that transmits urine from bladder to exterior
•Describe the gross anatomy of the kidney and its coverings - correct answer - bean shaped lateral
surface and concave medial surface
- internal structure: cortex, medulla and pelvis
- fibrous capsule thin layer of dense regular connective tissue surrounding the kidney
- renal fascia: outer dense fibrous connective tissue anchoring kidney to surrounding structures
- perirenal fat capsule: fatty mass that protects kidney
renal cortex - correct answer - superficial layer with granular appearance
renal medulla - correct answer 1. medullary pyramids: cone shaped tissue that appear stripe due to
parallel bundles of urine collecting tubes and capillaries
- renal columns: inward extensions of cortex separating pyramids
- lobes: pyramid surrounded by cortical tissue
- penetrated by loop of Henle
renal pelvis - correct answer - funnel shaped tube drains into ureter, collects all urine
renal hilum - correct answer - connection point for the ureters, renal artery, renal vein, lymphatics
and nerves
- where the ureter penetrates the kidney
renal corpuscle - correct answer - filters blood within the kidney
- interface between the blood supply and the kidney.
- consists of the glomerulus, which is a capillary bed, and the glomerular (bowman's) capsule, which is part of the nephron.
- Filtration is the exit of small substances from the blood in the glomerulus into the glomerular capsule of the nephron.
- All renal corpuscles are located in the renal cortex. A renal corpuscle consists of the glomerular capsule (Bowman's capsule) wrapped around the glomerulus (glomerular capillary bed). The renal corpuscle is where filtration occurs.
Glomeruler capillaries - correct answer - fenestrated
- allow all blood components except large plasma proteins and blood cells to pass through.
ureter - correct answer - long thin muscular tube that conveys urine from the kidneys to the urinary
- mucosa: transitional epithelium and lamina propria
- muscularis: inner longitudinal outer circular smooth muscle
- adventitia: outer CT layer holding ureter in place
- peristaltic waves of contraction propels urine towards bladder
urinary bladder - correct answer - stores urine delivered by ureters
The urinary bladder is very distensible
- When empty, wall is thrown into folds called rugae; disappear when bladder is stretched full with urine
•Trace the blood supply through the kidney - correct answer - rish blood supply, receives 1/4 of
total cardiac output
- renal artery
- segmental artery
- interlobar artery •Trace the flow of urine through the organs of the urinary system and describe the structure of each
organ - correct answer - Cortex, medulla, minor calyx, major calyx, renal pelvis, ureter
- Filtration occurs in the renal cortex, processing of the filtrate occurs within the renal tubules. Urine exits the renal pyramids into the minor calyces, then major calyces, then renal pelvis, where it will be conveyed to the urinary bladder by the ureter.
micturition - correct answer - the act of emptying the bladder
- urine fills bladder and stretches its wall
- stretch receptors send a signal via sensory afferent fibers to the sacral portion of the spinal cord
- parasympathetic efferent fibers stimulate the detrusor muscle to contract and the internal urethral sphincter to relax
renal artery - correct answer - brings high pressure oxygenated blood to the hilum of the kidney for
cleansing and filtration •Describe the anatomy of a nephron, including the major structures and subdivisions of the renal
corpuscle and renal tubules - correct answer - nephron: basic structural and functional unit of the
kidney
- consists of renal corpuscle, renal tubule, and collecting duct
- different parts of nephron reside in different areas of kidney: such as the cortex and medulla
cortex contains what parts of nephron - correct answer - contains all renal corpuscles, proximal
convoluted tubules and distal convoluted tubules
- 85% of nephrons are cortical
medulla contains what parts of nephron - correct answer - contains the straight structures: loops of
Henle, collecting ducts and vasa recta blood vessels
- renal corpuscle located bear the cortex-medulla junction
- loop of Henle dips deep into the medulla
- primary role: establish osmotic gradient in kidney
renal corpuscle - correct answer - consists of the glomerulus (capillary bed), and glomerular
capsule: cap surrounding glomerulus
- location where pre-urine is created by squeezing water and small solutes out of the glomerular capillaries
- this fluid is collected in the glomerular capsule and called filtrate (as it is driven by filtration pressure)
filtrate - correct answer - starting form of urine
- the body makes a lot more filtrate than urine
pathway of filtrate - correct answer 1. leaves Bowman's capsule and travels through a long hollow
tubule lined by epithelial tissue
renal tubule - correct answer 1. proximal convoluted tubule: leads out of glomerular capsule
- loop of henle: descending limb into medulla, ascending limb back to cortex
- distal convoluted tube: leads to collecting duct
As filtrate moves down the descending limb of the nephron loop: - correct answer its concentration
increases
If the filtrate concentration is lower than normal at the turn of the nephron loop: - correct answer
active transport in the thick ascending limb will be less efficient Submit
collecting duct - correct answer - collect from many nephrons and completes modification of urine
•List and describe the three major renal (urinary) processes responsible for urine formation -
correct answer - relies on glomerular filtration, tubular reabsorption, and tubular secretion
tubular secretion - correct answer - selectively adds to the filtrate
- process by which body gets of substances it doesn't want by moving them from blood to filtrate in the lumen of the tubule
- secretion happens by active transport only
review of capillary - correct answer - small holes allow for solutes and water to move across
capillary wall
- blood moves from arteriole across capillary bed to venule
- exchange with interstitial space occurs along the way
capillary exchange - correct answer - filtration: water and small solutes squeezed out of capillary
and into interstitial fluid (driven by blood pressure-passive)
- reabsorption: water drawn back into capillary from interstitial fluid, pulled by osmotic pressure exerted by large plasma proteins trapped in blood
smooth muscle in arteriole wall is adjustable - correct answer - vasodilation: increases blood flow
into capillary bed and increases filtration pressure
- vasoconstriction: decreases blood flow and filtration pressure
•Describe the structure of the filtration membrane - correct answer 1. fenestrated endothelium of
glomerular capillary: allows passage of everything but blood cells
- basement membrane: repels negatively charged macromolecules (plasma proteins)
- filtration slits between foot processes of podocytes (visceral layer o fglomerular capsule): slit diaphragm cover filtration slits add a final barrier to macromolecules. Glomerular mesangial cells to phagocytize debris (podocyte filtration slits, basal lamina, fenestrated glomerular capillaries)
- protein would be found in higher concentration (in the filtrate) if the filtration membrane were damaged
•Describe the forces (pressures) that promote or oppose glomerular filtration - correct answer -
glomerular hydrostatic pressure: pressure of fluid against walls of a vessel (can be within blood vessel or capsular space)
- osmotic pressure: exerted by particles in the blood which tend to pull water into the vessel or space
- these pressures can oppose each other by pulling water in opposite directions
- net pressure: sum of all opposing forces
glomerular hydrostatic pressure - correct answer - force with which blood pushes on the walls of
the glomerular capillary
- these capillaries or fenestrated so when blood flows through them the GHP will drive water and small solutes into the capsular space
- determined by blood pressure (50 mm Hg in capsule)
- An increase in blood pressure will cause an increase in GHP
Two forces oppose filtration - correct answer 1. capsular hydrostatic pressure: hydrostatic pressure
of filtrate as it accumulates in the capsular space and pushes on its walls
- tends to push water and solutes out of filtrate and into the plasma
- 10mm Hg
- opposes the force of water
- glomerular colloid osmotic pressure: due to osmotic gradient created by large solutes that remain in blood
- this pressure pulls fluid back into the capillary by osmosis
- 30 mm Hg and opposes filtration
- combine three forces to find net filtration pressure which drives filtration Suppose that a patient has a failing liver and is unable to make normal levels of albumin for the blood plasma. If all other factors remain the same, what would be the effect on the amount of
filtrate produced? If you need help with this question, check the hint. - correct answer Filtrate
production would increase. What do capsular hydrostatic pressure (CHP or HPcs) and glomerular colloid osmotic pressure (GCOP
or OPgc) have in common? - correct answer - they both oppose filtration
capsular colloid osmotic pressure - correct answer - usually zero because plasma proteins don't
enter the capsular space
net filtration pressure - correct answer CHP-(GCOP+CHP)
- cannot separately adjust salt and water
- 65-70% of Na+, K+ is reabsorbed, plus many other electrolytes (e.g. Cl-, HCO3-).
- All glucose and amino acids are reabsorbed
- Water follows by osmosis
- Some secretion occurs (urea, drugs)
- automatic, not regulated
nephron loop - correct answer - thin descending limb where only water leaves
- purpose: pump out salt so filtrate becomes more dilute
- makes a hairpin turn
- followed by thick ascending tube into the medulla
- thick and thin refer to thickness of the wall
distal convuluted tubule (DCT) - correct answer - carries filtrate into the collecting duct
- dips into medulla and carries final filtrate (urine)
- histology: simple cuboidal cells, less active transport, few microvilli
collecting ducts - correct answer - pass down through the medulla and harness gradient to adjust
the final water content in the urine
- adjusting sodium and pH •Describe the mechanisms underlying water and solute reabsorption from the renal tubules into the
peritubular capillaries - correct answer - The peritubular capillaries and the vasa recta are low
pressure capillary beds associated with the renal tubule
- Efferent arteriole gives rise to peritubular capillary bed
- Surround PCT and DCT in cortex - will reclaim (reabsorb) most of the solutes and water from the filtrate
ultrafiltrate - correct answer The ultrafiltrate is collected within the renal cortex.
The ultrafiltrate has the same osmolarity as blood plasma. The ultrafiltrate is similar to blood plasma.
transport maximum - correct answer - number of transport proteins available in tubule cell
membrane
- all cells are saturated and some glucose is not absorbed and ends up in the urine
•Compare and contrast tubular reabsorption and secretion - correct answer 1. tubular
reabsorption: reclaims what the body needs to keep
- occurs in the proximal convoluted tubule
- Proximal Convoluted Tubule (PCT)
- Reabsorption of all nutrients, electrolytes, most Na+ and water (obligatory reabsorption) Descending limb of nephron loop
- Reabsorption of water only through aquaporins
- Reabsorption of solutes (Na+, K+, Cl-)
- tubular secretion: selectively adds to the filtrate
- moves substances that we don't want from the peritubular capillaries through the tubule cells into the filtrate
reabsorption - correct answer - involves removing nutrients and water from the lumen of the
gastrointestinal tract and delivering them to the blood or lymph??
•Describe the mechanisms responsible for the medullary osmotic gradient - correct answer - The
medullary osmotic gradient is an increase in the concentration of solutes (osmolarity) in the interstitial space as you go deeper in the renal medulla.
- increasing osmotic gradient extends through the renal medulla. The gradient starts at the cortical- medulla junction at 300 mOsm (isotonic to the blood) and increases in osmolarity as you move deeper in the medulla (toward the apex of the renal (medullary) pyramid).
- the kidneys have an osmotic gradient extending from the cortex through the depths of the medulla
- in the medulla there is an increase concentration gradient and become more concentrated further in
- juxtamedullary nephrons have loops that dip all the way into the medulla
- ascending limb lined by simple cuboidal with transporters
- as filtrate travels through, water will continue to leave to enter area of higher concentration
- When the concentrated filtrate starts to go up the ascending limb, the salt transporters in the epithelial cells start to actively transport Na, Cl and K into the interstitial space
- very dilute when it reached distal convuluted tube
countercurrent exchangers - correct answer - vasa recta
- have capillary beds that are formed by efferent arteriole from the juxtamedullary nephrons
- maintains medullary osmotic gradient
- Reabsorption of nutrients like glucose and amino acids takes place in the proximal convoluted tubule (PCT) via cotransporters that utilize secondary active transport. Which of the following would
stop the reabsorption of glucose at the apical surface of the cells in the PCT? - correct answer a.
loss of Na+-K+ ATPase pump in the basolateral surface of PCT cells
- The mechanism that establishes the medullary osmotic gradient depends most on the
permeability properties of the ________. - correct answer - nephron loop
- the filtrate flow through the descending and ascending limbs of the nephron loops of juxtamedullary nephrons
- the descending limb's permeability to water and impermeability to salts
- the ascending limb's impermeability to water and permeability to salts
3. The descending limb of the nephron loop ________. - correct answer a. Contains fluid that
becomes more concentrated as it moves down into the medulla.
4. The mechanism of water reabsorption by the renal tubules is ________. - correct answer
osmosis
•Define glomerular filtration rate and the factors that modify it - correct answer - the total volume
of filtrate created by both kidneys each minute
- closely tied to homeostasis
- adjustments to glomerular hydrostatic pressure are the easiest way to impact NFP and therefore GFR
- GFR increase: more filtrate produced, urine output increases, blood volume and pressure decrease
- GFR decrease: less filtrate formed, less urine output, blood volume and pressure increase
- Intrinsic controls (also called renal autoregulation): myogenic mechanism and tubuloglomerular feedback
- act locally within the kidney to maintain GFR despite changes in systemic blood pressure
- changes are minute to minute in response to normal fluctuating changes in blood pressure - allow kidney "to do its job"
- Extrinsic controls - under extreme conditions in which blood pressure falls outside normal range (i.e. hypovolemic shock), nervous system and endocrine (hormonal) systems kick in to maintain systemic blood pressure and preserve blood flow to brain, vital organs (sometimes to the detriment of the kidneys). •Explain the mechanisms of renal autoregulation (the intrinsic control mechanisms that regulate GFR)
- correct answer - occurs locally in kidney to maintain GFR despite changes in the systemic blood pressure
- Myogenic Mechanism: Smooth muscle reflexively contracts when stretched & relaxes when not stretched - inherent property of smooth muscle Increased systemic blood pressure stretches afferent arteriole causing reflexive smooth muscle contraction - blood flow into glomerulus ↓ preventing GFR ↑
- Tubuloglomerular Feedback Mechanism •Directed by macula densa cells in juxtaglomerular apparatus •Macula densa cells:monitoring the NaCl content of the filtrate in the ascending limb of loop •When GFR increases, time to reabsorb NaCl goes down, and the concentration of NaCl in the ascending limb of loop goes up! •Macula densa cells release vasoconstrictor chemicals constricting the afferent arteriole •Glomerular hydrostatic pressure decreases and GFR is decreased - allows more time for NaCl reabsorption •Describe and explain the neuronal and hormonal controls of glomerular filtration rate (extrinsic
control mechanisms) - correct answer - come from outside the kidney and include nervous system
control and endocrine control which are regulated by key hormones
- renin-angiotensin-aldosterone system
- Norepinephrine from nerve fibers; Epinephrine from adrenal medulla
Water is reabsorbed from collecting duct (into capillaries). Small amount of concentrated urine is produced because we want to conserve water.
- ADH: determine if water can be reabsorbed by inserting aquaporins into collecting duct cells
- urea: waste product, aids in formation of osmotic gradient, cycles between collecting duct, interstitium and ascending loop
- diuretics: increase urine output
•Describe the general locations of tubular secretion and the types of substances secreted - correct
answer - secretion occurs across length of the nephron
granular cells - correct answer - mechanoreceptors that sense blood pressure in the afferent
arterioles.
- They secrete renin when the blood pressure drops and are an important part of the renin- angiotensin-aldosterone regulatory pathway (one of the extrinsic control mechanisms)
Pathway of filtrate and urine - correct answer 1. renal corpuscle: site of production
- filtrate travels through the tubule system of the nephron
- out the collecting duct
- urine flows out of the kidney
- down the ureters
- into bladder
- out of urethra
- URINE STAYS THE SAME DURING THIS PROCESS
excretion - correct answer - process of eliminating waste
How more material is added to the urine - correct answer - filtrate from the blood at the
glomerulus
- and add material in along the tubule through secretion
•Describe the normal physical and chemical properties of urine - correct answer - color: indication
of hydration or blood in the urine
- pH: affected by diet (high protein-acidic, vegetarian-alkaline)
- smell
- turbidity: clear-normal, suspended particles- increased turbidity
- constituents: water, urea, salts, pigments •Define renal clearance and explain how this value summarizes how substances are handled by the
kidney - correct answer - how quickly a substance is removed from plasma
- indicator of kidney function over time
- Renal clearance: the volume of plasma from which the kidneys clear a particular substance in one minute
- tells us how a substance is handled by the kidney- clinical tool
•Describe why renal clearance of inulin and creatinine can be used to estimate GFR - correct
answer - inulin: a compound that is freely filtered and is not secreted or reabsorbed. The rate at
which inulin shows up in urine is the same as glomerular filtration rate
- creatinine: natural body substance (breakdown product of muscle creatine phosphate) produced at constant rate, little absorbed, some secreted. Used as estimate for GFR
renal clearance types - correct answer 1. equal to inulin: substance is filtered but neither
reabsorbed or secreted
- less than inulin: substance is filtered but some is reabsorbed by the tubule cells
- more than inulin: substance is filtered but also being secreted by the tubule cells and added to the filtrate (more in the urine)
assessment of kidney function - correct answer - measure levels of nitrogenous waste in blood
- urine output
- monitering appearance
- GFR
failing kidneys treatment - correct answer - dialysis
