P PP P P
Exam
I
Exam
II
Today:
A. Kidney anatomy
B. Kidney physiology
Mariners
Indians
2
4
Mariners
Indians
3
5
Mariners
Indians
12
4
Exam 1 - Example Problems:
(1) Multiple Choice:
Which of the following conditions would result in an increase
in blood pressure?
(A) increase in blood vessel diameter
(B) decrease in blood volume
P (C) decrease in blood vessel elasticity
(D) decrease in blood vessel length
(E) all of the above
(2) True/False:
F The right ventricle of the heart has a much thicker
____
muscular layer than the left ventricle
(3) Fill-in-Blank:
Erythropoietin
_____________
is the hormone produced by the kidney that
is responsible for red blood cell formation.
Exam 1 - Example Problems:
Chapters 26: Urinary System
The Urinary System:
(4) Matching:
Kidneys ain’t just
for pee’n
Match the following vessel names with their location
on the diagram...
Match the following formed element in the blood with the
correct description...
(5) Short Answer:
Briefly describe (2-3 sentences) the following term/concepts:
Veins
Coagulation
One type of short-term neural mechanism utilized by the body
to maintain blood pressure is the baroreceptor-initiated reflex.
Briefly describe the events involved in a baroreceptor-inititated
reflex in response to a fall in systemic blood pressure...
Major Functions:
1) Eliminate waste materials
2) Control volume / composition
of body fluids
3) Produce renin (blood pressure regulator)
4) Produce erythropoietin
(stimulates RBC formation)
5) Metabolize vitamin D to active
form (Ca++ uptake)
Chapters 26: Urinary System
Urinary System Anatomy:
Chapters 26: Urinary System
Urinary System Anatomy:
Kidney:
Hilus
Cortex
Medulla
Kidney
Renal
pyramids
Kidneys (retroperitoneal)
Ureters
Urinary bladder
Urethra
Pelvis
Renal
columns
Ure
ter
1)
2)
3)
4)
Renal artery
Renal vein
Calyces (calyx)
Chapters 26: Urinary System
Urinary System Anatomy:
Blood Supply to Kidneys:
• 1/4 of cardiac output delivered to kidneys
• 0.25 x 5 L/min = 1.25 L/min
• Kidneys only 0.5 % of total body mass
Nephron: Functional unit of the kidney (urine formation)
• ~ 1 million / kidney
• Filter ~ 200 L of blood plasma / day
Chapters 26: Urinary System
Urinary System Anatomy:
Nephron Anatomy:
1) Glomerulus
• Network of capillaries (filtration site)
• Tightly wound coil (> surface area)
2) Tubule
• Location where filtrate → urine
• Produce ~ 1 - 1.5 L of urine / day
• 99% of filtrate returned to blood
Chapters 26: Urinary System
Urinary System Anatomy:
Nephron Tubule Anatomy:
1) Bowman’s Capsule
• Expanded proximal end of tubule
• Surrounds glomerulus
• Outer layer = Simple squamous epithelium
• Inner layer = Podocytes (foot cells)
• Filtration slits = Area between podocytes
Filtrate enters tubule
through slits / fenestrations
Chapters 26: Urinary System
Urinary System Anatomy:
Nephron Tubule Anatomy:
4) Distal Tubule
• Simple cuboidal epithelium (w/o microvilli)
• Acid/base balance (pH)
• Secretion of materials into tubule (K+, H+, drugs)
• Target region of ADH and aldosterone
5) Collecting Duct
• Simple cuboidal epithelium
• Collects almost completely formed urine
• ~ 3x [solute] of blood
Chapters 26: Urinary System
Urinary System Anatomy:
Nephron Tubule Anatomy:
2) Proximal Tubule
• Adjacent to Bowman’s capsule
• Simple cuboidal epithelium (microvilli)
• ~ 80 % of reabsorption occurs here
3) Loop of Henle
• Ascending and descending portions
• Simple squamous epithelium
• Water conservation
Chapters 26: Urinary System
(Figure 26.4)
Chapters 26: Urinary System
Chapters 26: Urinary System
Urinary System Anatomy:
Types of Nephrons:
1) Cortical Nephrons (85%):
• Located entirely in the cortex
• Short loops of Henle
2) Juxtamedullary Nephrons (15%):
• Bowman’s capsule in cortex; loop of Henle in medulla
• Long loops of Henle
Chapters 26: Urinary System
Urinary System Anatomy:
Blood Supply
to Nephrons:
Chapters 26: Urinary System
Urinary System Physiology:
Glomerular capillaries
Afferent arteriole
Urinary System Anatomy:
Blood Supply to Nephrons:
• 2 capillary networks in series:
1) Glomerulus (filtration)
2) Peritubular capillaries (reabsorption)
• Single day → kidneys filter 60x normal blood plasma
volume present
• Consume 20 - 25 % of all oxygen at rest
Efferent arteriole
• Filtrate = all blood borne solutes except proteins
Urine = metabolic waste and unneeded solutes
• Major processes in urine formation:
1) Glomerular filtration (glomeruli)
Bowman’s
capsule
Peritubular
capillaries
Interlobular artery
2) Tubular reabsorption (renal tubules)
3) Tubular secretion (renal tubules)
Tubule
Chapters 26: Urinary System
Chapters 26: Urinary System
Urinary System Physiology:
Urinary System Physiology:
Glomerular Filtration:
1) Blood pressure = driving force
Urine Formation:
Filtration
Reabsorption
Secretion
Urine Production
(to
interlobular
veins)
Chapters 26: Urinary System
Chapters 26: Urinary System
Urinary System Physiology:
Glomerular Filtration:
1) Blood pressure = driving force
Urinary System Physiology:
Glomerular Filtration:
1) Blood pressure = driving force
Colloid
Osmotic
Pressure
Net Filtration
Rate
Capsular
Hydrostatic
Pressure
=
Chapters 26: Urinary System
Urinary System Physiology:
Glomerular Filtration:
1) Blood pressure = driving force
55 mm Hg
-
(15 mm Hg + 30 mm Hg)
Chapters 26: Urinary System
(Figure 26.9)
Glomerular
Hydrostatic
Pressure
Colloid
Osmotic
Pressure
Net Filtration
Rate
Glomerular
Hydrostatic
Pressure
Capsular
Hydrostatic
Pressure
= 10 mm Hg
Chapters 26: Urinary System
Urinary System Physiology:
Glomerular Filtration:
1) Blood pressure = driving force
2) Molecules filtered < 3 nm diameter
• Water, glucose, amino acids, ions, nitrogenous waste
• Blood cells / proteins too large
Chapters 26: Urinary System
Urinary System Physiology:
Glomerular Filtration:
1) Blood pressure = driving force
2) Molecules filtered < 3 nm diameter
Capillary
endothelial cell
Basement
Membrane
Podocytes
Filtration
membrane
Filtration slits
Water, glucose, amino acids,
ions, nitrogenous waste
Chapters 26: Urinary System
Urinary System Physiology:
Glomerular Filtration:
1) Blood pressure = driving force
2) Molecules filtered < 3 nm diameter
3) Glomerular filtration rate (GFR):
• Volume of fluid filtered into Bowman’s capsule / minute
• Normal adult = 120-150 ml/min
• Factors governing filtration rate:
1) Surface area
2) Filtration membrane permeability
3) Net filtration pressure (↓15% GHP = no filtration)
Chapters 26: Urinary System
Chapters 26: Urinary System
Urinary System Physiology:
Glomerular Filtration:
1) Blood pressure = driving force
2) Molecules filtered < 3 nm diameter
3) Glomerular filtration rate (GFR):
• Regulation of GFR:
a) Myogenic control (intrinsic)
• Afferent arteriole diameter directly related to flow in vessel
↑ BP
=
↓ BP
=
↑ constriction of afferent arteriole
Smooth muscle
relaxes
=
Afferent arteriole
dilates
Chapters 26: Urinary System
Urinary System Physiology:
Glomerular Filtration:
1) Blood pressure = driving force
2) Molecules filtered < 3 nm diameter
3) Glomerular filtration rate (GFR):
• Regulation of GFR:
a) Myogenic control (intrinsic)
b) Tubuloglomerular feedback mechanism (intrinsic)
• Macula densa cells (distal tubules) monitor:
a) Rate of fluid flow in tubules
b) level of Na+ in tubules
Chapters 26: Urinary System
Urinary System Physiology:
Glomerular Filtration:
1) Blood pressure = driving force
2) Molecules filtered < 3 nm diameter
3) Glomerular filtration rate (GFR):
• Regulation of GFR:
a) Myogenic control (intrinsic)
b) Tubuloglomerular feedback mechanism (intrinsic)
• Macula densa cells (distal tubules) monitor:
a) Rate of fluid flow in tubules
b) level of Na+ in tubules
• ↓ flow / ↓ osmolarity = vasodilation (afferent arteriole)
• ↑ flow / ↑ osmolarity, vasoconstriction (afferent art.)
Chapters 26: Urinary System
Urinary System Physiology:
Glomerular Filtration:
1) Blood pressure = driving force
2) Molecules filtered < 3 nm diameter
3) Glomerular filtration rate (GFR):
• Regulation of GFR:
a) Myogenic control (intrinsic)
b) Tubuloglomerular feedback mechanism (intrinsic)
c) Sympathetic nervous system (extrinsic)
d) Renin-angtiotensin mechanism (extrinsic)
• Juxtaglomerular cells monitor blood pressure
• If BP ↓, release renin into blood (↑ BP)
Chapters 26: Urinary System
Chapters 26: Urinary System
Urinary System Physiology:
Urine Formation:
Filtration
Reabsorption
Chapters 26: Urinary System
Urinary System Physiology:
Tubular Reabsorption:
• Return of fluid from renal tubules to blood
• ~ 80% of water & solutes reabsorbed at proximal tubule
1) Active processes:
• Chemicals moved against gradient
• Requires ATP (pumps in epithelial cell membranes)
• Substances = Glucose, amino acids, most cations (e.g. Na+)
2) Passive processes:
• Chemicals move down gradients (diffusion)
• Gradients established across epithelial membranes
Chapters 26: Urinary System
Assisting movement into
blood:
• Highly permeable
basement membrane
• Low blood pressure and
high [protein] in capillary
Transport Maximum (Tm)
Ø Diabetes
Solvent Drag
Obligatory water reabsorption
(Figure 26.12)
Chapters 26: Urinary System
Urinary System Physiology:
Tubular Reabsorption:
Absorptive Capabilities of Tubules:
Proximal
Convoluted
Tubule
Glucose (100%)
Amino acids (100%)
Na+ (~ 70%)
Water (~ 70%)
HCO3- (~ 90%)
Cl- (~ 50%)
Chapters 26: Urinary System
Urinary System Physiology:
Tubular Reabsorption:
Non-reabsorbed Substances:
• End products of protein / nucleic acid metabolism
Loop of Henle
Distal Convoluted
Tubule & Collecting Duct
Na+ (~ 25%)
Water (~ 25%)
Cl- (~ 35%)
Na+ (hormone dependent)
Water (hormone dependent)
Cl- (hormone dependent)
• Urea*, creatinine, uric acid*
• Not reabsorbed because:
(1) Lack protein carriers
(2) Not lipid soluble
(3) Too large to pass through membrane pores
Chapters 26: Urinary System
Urinary System Physiology:
Chapters 26: Urinary System
Urinary System Physiology:
Tubular Secretion:
• Movement of material from capillary / tubule cells to filtrate
• Proximal tubules / distal tubules / collecting ducts
• Function:
1) Eliminating substances not in filtrate (e.g. antibiotics)
Urine Formation:
Filtration
Reabsorption
Secretion
2) Eliminating substances reabsorbed (e.g. urea)
3) Eliminating excess K+ (collecting ducts)
4) Balancing pH (proximal / distal tubules)