Upgrade to remove ads
Physiology final exam CPP Nguyen
Terms in this set (83)
5 functions of the kidneys
filter toxins, reabsorb essential nutrients, excrete wastes, produce erythropoietin, secrete renin.
The kidneys are located in the.
Urine flows from the
kidney, through the ureters into the bladder and then is excreted via the urethra.
Each nephron consists of a renal corpuscle, which
contains the glomerular capillaries
The tubule forms a cup shape around the glomerulus called the
glomerular capsule or Bowman's capsule.
Each nephron consists of
1. renal corpuscle
2. a renal tubule that extends from the renal
The outer portion is the renal cortex,
and the inner portion is the renal medulla.
The cortex contains
all the renal corpuscles
Types of Nephrons
- At the border between the cortex and medulla.
- Long loop of Henle.
- Involved in the concentration of
- About 15% of all nephrons.
- Most nephrons.
- Short loop of Henl
The combination of a glomerulus and a Bowman's capsule =
bout 20% of the plasma filters into .
Bowman's space by a filtration barrier consisting of three layers:
1. the fenestrated, single-celled capillary endothelium;
2. a basement membrane (basal lamina) and;
3. the single-celled epithelial lining of Bowman's capsule (Podocytes).
-The inner layer of the glomerular capsule contains highly modified branching epithelial cell
-Podocytes terminate in foot processes which surround the basement membrane of the glomerulus.
• The clefts between the foot processes are called filtration slits
substances in the blood are filtered
through capillary pores between endothelial cells.
specialized for filtration
• The glomerular capillaries are specialized for filtration.
• These are the only capillaries in the body that are fed and drained by an arteriole (afferent and efferent).
• This allows the blood pressure in the capillary bed to be very high and it forces fluid and solute out of the blood into the glomerular capsule
• Most of the filtrate is reabsorbed in the renal tubule cells and returns to the blood through the peritubular capillaries.
juxtaglomerular cells are
muscle cells in the arteriole wall.
These mechanoreceptors detect blood pressure in the afferent arteriole.
The macula densa is a group of
tall, closely- packed cells that are adjacent to the juxtaglomerular cells.
macula densa cells are chemoreceptors that respond to changes in the NaCl content of the filtrate.
combination of macula densa and juxtaglomerular cells
The bladder stores urine until it is excreted from the body by the
micturition reflex which causes the smooth muscle of the bladder walls to contract and the expel the urine
Unintentional leakage of urine.
leak during actives like coughing, sneezing, laughing
leaking after a strong urge
the combination of stress incontinence and urge incontinence
can occur in association with factors such as severe constipation, infections in the urinary tract or vagina, or medication usage
-frequent and sudden urination
The bladder is a chamber with smooth muscle walls, collectively termed
the detrusor muscle, which squeezes on the urine in the bladder lumen to produce urination.
Contraction of the external urethral sphincter
can prevent urination even when the detrusor muscle contracts strongly
Involuntary Spinal Control - Bladder
1. As the bladder fills with urine, the pressure within it increases, which stimulates stretch receptors in the bladder wall.
2. The afferent neurons from these receptors enter the spinal cord and stimulate the parasympathetic neurons, which then cause the detrusor muscle to contract.
3. When the detrusor muscle contracts, the change in the shape of the bladder pulls open the internal urethral sphincter. Simultaneously, the afferent input from the stretch receptors reflexively inhibits the sympathetic neurons to the internal urethral sphincter, which further contributes to its opening.
4. In addition, the afferent input also reflexively inhibits the somatic motor neurons to the external urethral sphincter, causing it to relax.
5. Both sphincters are now open, and the contraction of the detrusor muscle can produce urination.
Voluntary Control - Bladder
- Urination can be voluntarily prevented by activating descending pathways that stimulate both the sympathetic nerves to the internal urethral sphincter and the somatic motor nerves to the external urethral sphincter.
• In contrast, urination can be voluntarily initiated via the descending pathways to the appropriate neurons.
decreased = relaxation of internal urethal sphincter = opening internal urethal sphincter
= mictrution reflex
works with para
increased = contraction of detrusor muscles = opening internal urethal sphincter
= mictrution reflex
paired with symp
decreased = relaxation of external urethral +
= opening internal urethal sphincter
= mictrution reflex
glomerulus filtration rate average
65% of these substances are reabsorbed
Na+ Cl- H20 K+
90% of these substances are reabsorbed
HC03- , MAINTAINS PH
100% of these substances are absorbed
amino acids, glucose
50% of urea
secretion in nephron
ammonia and other drugs are secreted into the tubes
loop of henlly
descending and ascending limb
ascending limb is
impermeable to water and highly salty
is permeable to water but has low permeability to NA+
BOTTOM OF HENLEY
highly concentrated filtrate
end of henley result
25% of sodium chloride is reabsorbed and the filtrate is diluted
distal convoluted tubule
under influence of aldosterone sodium and chloride are reabsorbed and hydrogen and potassium are secreted into it, remaing bicarbonate is reabsorbed and small amount of water
final adjustments made before becoming urine, NACL & UREA IS reabsorbed ,
adh in urinary
maintains water in collecting duct, if you are dehydrated adh creates aquaporins which open water channels in collecting duct,
General ingredients in urine
Na+ CL- K+
conceptual equation for filtration excretion
(amount filtered) + (secretion) - (reasboriton) = urine excreted
About 20% of the _______ filters into Bowman's capsule.
how substances are reabsorbed
through diffusion or mediated transport into the intersitial fluid
The volume of plasma that is completely cleared of a specific compound per unit time, measured as a test of kidney function.
excess creatine means something wrong with gromulear
Mediated transport systems have a limit to the amount they can transport per unit time called the
This transport maximum is why untreated diabetic patients have glucose in their urine
Plasma glucose concentration in a healthy person
not exceed 150 mg/100 mL
is the process by which hydrostatic
pressures force fluid and solutes through a membrane.
• Glomerular pressure is higher (~55 mm Hg), so they produce 180 L/day vs. 3-4 formed by other capillary beds.
During filtration it is important to keep the plasma proteins in the plasma to maintain
osmotic (oncotic) pressure
why the gromeular doesn't filter proteins
1. renal corpuscles dont support/restrict that weight
2.filtration pathways in the corpuscular membranes are negatively charged, so they oppose the movement of these plasma proteins, most of which are also negatively charged
If you see blood cells or protein in the urine then
there is a problem with the filtration membrane.
• This is a common finding during diabetes and hypertension that signals that kidney damage has occurred.
• If untreated will progress to end stage renal disease and renal failure.
What are the Starling forces
1. the hydrostatic pressure difference across the capillary wallthat favors filtration
2. the protein concentration difference across the wall that creates an osmotic force that opposes filtration
Sodium reabsorption is an active process occurring in all tubular segments except .
the descending limb of the loop of Henle and the medullary collecting duct.
Sodium is reabsorbed (>99%) and not secreted
understand that under normal conditions, salt and water
salt and water losses exactly equal salt
and water gains.
Na+ is reabsorbed by
primary active transport across the basolateral
membrane throughout the tubule (except for the descending limb of the loop of Henle).
in the Cortical Collecting Duct (Downhill)
Movement across the basolateral membrane is the same in all regions that absorb Na+ (primary active transport). This transport process decreases intracellular [Na+] and thereby makes downhill movement of Na+ across the apical membrane possible.
Movement across the apical membrane varies from one segment to another.
High Na+ results
in high blood volume and thus, higher blood pressure.
Lower pressures initiate
baroreflexes that influence the renal arterioles and tubules so as to decrease GFR and increase Na+ reabsorption
these events decrease Na+ excretion, thereby retaining Na+ (and therefore water) in the body and preventing further decreases in plasma volume and cardiovascular pressures.
Low sodium = low blood pressue =
• Decreased glomerular filtration pressure occurs as a consequence of decreased arterial pressure in the kidneys and, more importantly, as a result of reflexes acting on the renal arterioles.
• This is a baroreceptor reflex response.
The major factor determining the rate of tubular Na+ reabsorption
is the hormone aldosterone.
- Increase the number of Na+/K+ pumps on basolateral membrane. - increases the number of open Na+ and K+ channels on apical
Renin is an enzyme secreted by the juxtaglomerular cells of the juxtaglomerular apparatuses in the kidneys.
• ACE enzyme is found on the apical surface of capillary endothelial cells.
What controls the secretion of aldosterone under these circumstances?
Angiotensin II acts directly on the adrenal cortex to stimulate the secretion of aldosterone.
Three inputs all stimulating renin release.
1. Increasing of renal sympathetic nerves (direct)
2. decreased arterial pressure (direct)
3. decreased GFR , decreased flow to macula densa (indirect)
Changes in GFR initiated by baroreceptors have the same effects on water excretion
as on Na+ excretion.
The difference in water concentration between the lumen and the interstitial fluid causes
net diffusion of water from the lumen, across the tubular epithelial cells' plasma membrane
and/or tight junctions into the interstitial fluid.
osmoreceptors and baroreceptors.
Vasopressin or ADH secreting neurons in the hypothalamus & posterior pituitary receive inputs from
If osmolarity increases due to water deprivation,
vasopressin is secreted from the posterior pituitary, causing the insertion of aquaporins into the membranes of the collecting duct epithelial cells and allowing water to be reabsorbed into the body.
Baroreceptor Control of Vasopressin Secretion
Decreased extracellular fluid volume stimulates aldosterone release via the renin-angiotensin system and increases vasopressin to help stabilize extracellular fluid volume.
hirst is stimulated by
a decrease in plasma volume (or extracellular fluid volume) and by an increase in plasma osmolarity.
sweat is a
sweating thus causes.
both a decrease in extracellular fluid volume and an increase in body fluid osmolarity
Deficits in salt and water must be replenished by ingestion of these substances
because the kidney cannot create new sodium or water
The stimuli for thirst are the same
as the stimuli for the release of vasopressin (ADH) from the posterior pituitary.
angiotensin II can stimulate
YOU MIGHT ALSO LIKE...
PGY 412G Renal System
The Urinary System
The Urinary System
OTHER SETS BY THIS CREATOR
Chapter 15, 17, 18
Exam 2 HRT
Chapter 13 Micro bio
Microbio Chapter 11