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Chapters 18 - 20: Cardiovascular System
P PP P
Blood Vessel - Physiology:
Exam
I
To stay alive, blood must be kept moving...
Exam
II
Today:
A. Regulation of BP
B. Capillary dynamics
C. Kidney anatomy
Mariners
Tigers
4
2
Blood Flow:
Volume of blood flowing past a point
per given time (ml/min)
Blood Pressure:
Force per unit area on wall of
vessel (mm Hg)
Blood Flow = Difference in blood pressure (∆ P)
Chapters 18 - 20: Cardiovascular System
Blood Vessel - Physiology:
Chapters 18 - 20: Cardiovascular System
Blood Vessel - Physiology:
To stay alive, blood must be kept moving...
To stay alive, blood must be kept moving...
1
Peripheral resistance (R)
Blood Flow =
Peripheral Resistance:
Amount of friction blood encounters
passing through vessels
Previous:
Blood Flow = Difference in blood pressure (∆ P)
1) Blood viscosity
2) Vessel Length
3) Vessel Diameter
THUS:
Blood Flow =
↑ viscosity = ↑ resistance
↑ length = ↑ resistance
↓ diameter = ↑ resistance
Chapters 18 - 20: Cardiovascular System
Blood Vessel - Physiology:
Pressure gradients drive blood flow in body:
• Heart generates initial pressure
• Resistance in vessels generates pressure gradient
Difference in blood pressure (∆ P)
Peripheral resistance (R)
Chapters 18 - 20: Cardiovascular System
Blood Vessel - Physiology:
Atrial Pressure:
Systolic Pressure: Pressure from ventricular contraction (120 mm Hg)
Diastolic Pressure: Pressure from ventricular relaxation (80 mm Hg)
Pulse Pressure = systolic pressure - diastolic pressure (“pulse”)
Mean Arterial Pressure (MAP) = diastolic pressure + 1/3 pulse pressure
• “Average” pressure propelling blood in system
(Figure 20.5)
Chapters 18 - 20: Cardiovascular System
Chapters 18 - 20: Cardiovascular System
Blood Vessel - Physiology:
Capillary Pressure:
• Low pressure desirable:
1) Capillaries fragile
2) Capillaries extremely permeable
Blood Vessel - Physiology:
Blood Flow =
Venous Pressure:
• Pressure steady (no pulse)
• Blood return aided via:
1) Respiratory pump
2) Muscular pumps
Difference in blood pressure (∆ P)
Peripheral resistance (R)
Blood Pressure = Cardiac Output x
Peripheral
resistance (R)
(figure 20.6)
Chapters 18 - 20: Cardiovascular System
Chapters 18 - 20: Cardiovascular System
Blood Vessel - Physiology:
Mechanisms for Regulating Blood Pressure:
Short-term Mechanisms:
1) Neural Controls
a) Alter blood distribution
b) Alter vessel diameter to maintain blood pressure
• Operate via reflex arcs
Blood Vessel - Physiology:
Factors Affecting Blood Pressure:
Blood Pressure = Cardiac Output x
Peripheral
resistance (R)
1) Peripheral Resistance (↑ Resistance = ↑ BP)
a) Vessel Diameter (↓ D = ↑ BP)
b) Blood Viscosity (↑ V = ↑ BP)
c) Vessel Length (↑ L = ↑ BP)
• Chemoreceptor-initiated reflexes (O2 / pH / CO2)
• Baroreceptor-initiated reflexes (pressure)
2) Vessel Elasticity (↓ Vessel Elasticity = ↑ BP)
3) Cardiac Output (↑ Cardiac Output = ↑ BP)
4) Blood Volume (↑ Blood Volume = ↑ BP)
Chapters 18 - 20: Cardiovascular System
Chapters 18 - 20: Cardiovascular System
Blood Vessel - Physiology:
Baroreceptor-initiated reflexes:
Blood Vessel - Physiology:
Baroreceptor-initiated reflexes:
Falling blood pressure
Heart rate decreases;
Vessel diameter increases
(decreased cardiac output)
(decreased peripheral resistance)
Blood
Vessel
Inhibition of baroreceptors;
Reduced impulses to vasomotor center
(-)
Vasomotor
Center
(+)
(+)
(+)
Decreased parasympathetic activity;
Increased sympathetic activity
Aortic
Arch
Heart rate increases;
Vessel diameter decreases
SA
SLOW
Node
Increased blood pressure
(increased cardiac output)
(increased peripheral resistance)
Blood
Vessel
sympathetic
parasympathetic
Increased parasympathetic activity;
Decreased sympathetic activity
Reduced blood pressure
Vasomotor
Center
sympathetic
Activation of baroreceptors;
Increased impulses to vasomotor center
parasympathetic
Rising blood pressure
(-)
(-)
Aortic
Arch
SA
FAST
Node
Chapters 18 - 20: Cardiovascular System
Chapters 18 - 20: Cardiovascular System
Blood Vessel - Physiology:
Mechanisms for Regulating Blood Pressure:
Short-term Mechanisms:
2) Chemical Controls (Hormones)
• Norepinephrine (adrenals):
Blood Vessel - Physiology:
Mechanisms for Regulating Blood Pressure:
Long-term Mechanisms:
• Regulate BP via blood volume changes (kidneys)
1) Direct Mechanism:
• ↑ BP = Kidneys lose water
• ↓ BP = Kidneys conserve water
2) Indirect Mechanism:
• Vasoconstrictor (↑ BP)
• Epinephrine (adrenals):
• Increased cardiac output / vasoconstrictor (↑ BP)
• Antidiuretic Hormone (ADH - hypothalamus):
• Renin-angiotensin Mechanism:
• Increases blood volume / vasoconstrictor (↑ BP)
• Atrial Natriuretic Peptide (ANP - Atria):
• Decreases blood volume / vasodilator (↓ BP)
Renin
Angiotensin II
(Kidney)
(Vasoconstrictor)
• Nitric Oxide (NO) :
Aldosterone
(Conserve water)
Hypotension: Low blood pressure
Hypertension: High blood pressure (chronic = “silent killer”)
• Vasodilator (↓ BP)
Chapters 18 - 20: Cardiovascular System
Chapters 18 - 20: Cardiovascular System
Blood Vessel - Physiology:
Blood Flow through Body Tissues:
• The body automatically adjusts blood flow to cells (demand)
Methods of Autoregulation:
1) Metabolic Control:
• Nutritional status of tissues regulate flow
Blood Vessel - Physiology:
Blood Flow through Body Tissues:
Functions of Tissue Perfusion:
1)
2)
3)
4)
5)
ADH (conserve water)
Deliver oxygen / nutrients (cells)
Remove waste (cells)
Gas exchange (lungs)
Nutrient absorption (GI tract)
Urine formation (kidneys)
2) Myogenic Control:
• BP shifts regulate flow (stretch = vasoconstriction)
3) Vessel diameter / number increase (long-term autoregulation)
Velocity of Blood Flow:
Velocity inversely
related to cross-sectional
area of vessels
Chapters 18 - 20: Cardiovascular System
Chapters 18 - 20: Cardiovascular System
Blood Vessel - Physiology:
Capillary Dynamics:
Blood Vessel - Physiology:
Capillary Dynamics:
• Nutrients / waste pass via diffusion ([higher] to [lower])
• Fluid movement driven by hydrostatic / osmotic pressure
• Nutrients / waste pass via diffusion ([higher] to [lower])
• Fluid movement driven by hydrostatic / osmotic pressure
1) Hydrostatic Pressure: Force exerted by fluid against wall
a) Capillary Hydrostatic Pressure (HPC):
• Forces fluids out of capillary
Arterial
HPIF = 0 mm Hg
HPIF = 0 mm Hg
HPC = 35 mm Hg
HPC = 17 mm Hg
1) Osmotic Pressure: Diffusion of water (↓ [solute] to ↑ [solute])
a) Capillary Colloid Osmotic Pressure (OPC):
• Water enters capillary (blood proteins)
Arterial
Blood Flow
Blood Flow
Venous
Venous
OPC = 26 mm Hg
OPC = 26 mm Hg
OPIF = 1 mm Hg
OPIF = 1 mm Hg
Blood Flow
b) Interstitial Fluid Hydrostatic Pressure (HPIF):
• Forces fluids into capillary
b) Interstitial Fluid Osmotic Pressure (OPIF):
• Water exits capillary (Interstitial proteins)
Blood Flow
Chapters 18 - 20: Cardiovascular System
Lymphatic
System
Blood Vessel - Physiology:
Capillary Dynamics:
• Nutrients / waste pass via diffusion ([higher] to [lower])
• Fluid movement driven by hydrostatic / osmotic pressure
Net Filtration Pressure (NFP):
• Pressure acting at capillary after all forces accounted for
Arterial
HPIF = 0 mm Hg
HPIF = 0 mm Hg
HPC = 35 mm Hg
HPC = 17 mm Hg
35 - 25 = +10
Blood Flow
17 - 25 = -8
OPC = 26 mm Hg
OPC = 26 mm Hg
OPIF = 1 mm Hg
OPIF = 1 mm Hg
Venous
Blood Flow
• NFPArterial = Net movement of fluid out (10 mm Hg)
Chapters 18 - 20: Cardiovascular System
Blood Vessel - Physiology:
Circulatory Shock: Blood vessels inadequately filled
1) Hypovolemic Shock:
• Extreme vasoconstriction (& “thready” pulse)
• Large-scale blood loss
2) Vascular Shock:
• Extreme vasodilation
1) Anaphylaxis (allergies)
2) Failure of ANS regulation
3) Septicemia (bacteria)
3) Cardiogenic Shock
• Heart malfunctions
• NFPVenous = Net movement of fluid in (8 mm Hg)
Chapters 26: Urinary System
Chapters 26: Urinary System
The Urinary System:
Urinary System Anatomy:
Kidneys ain’t just
for pee’n
1)
2)
3)
4)
Major Functions:
1) Eliminate waste materials
2) Control volume / composition
of body fluids
3) Produce renin (blood pressure regulator)
4) Produce erythropoietin
Kidneys (retroperitoneal)
Ureters
Urinary bladder
Urethra
(stimulates RBC formation)
5) Metabolize vitamin D to active
form (Ca++ uptake)
Chapters 26: Urinary System
Urinary System Anatomy:
Kidney:
Hilus
Chapters 26: Urinary System
Cortex
Medulla
Kidney
Renal
pyramids
Renal artery
Renal vein
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
Pelvis
Ure
ter
Renal
columns
Calyces (calyx)
• Produce ~ 1 - 1.5 L of urine / day
• 99% of filtrate returned to blood
Chapters 26: Urinary System
Chapters 26: Urinary System
Urinary System Anatomy:
Nephron Anatomy:
1) Glomerulus
• Network of capillaries (filtration site)
• Tightly wound coil (> surface area)
2) Tubule
Urinary System Anatomy:
Nephron Tubule Anatomy:
1) Bowman’s Capsule
• Expanded proximal end of tubule
• Surrounds glomerulus
• Outer layer = Simple squamous epithelium
• Location where filtrate → urine
• Inner layer = Podocytes (foot cells)
• Filtration slits = Area between podocytes
Filtrate enters tubule
through slits / fenestrations
Chapters 26: Urinary System
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
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
3) Loop of Henle
• Ascending and descending portions
5) Collecting Duct
• Simple cuboidal epithelium
• Collects almost completely formed urine
• ~ 3x [solute] of blood
• Simple squamous epithelium
• Water conservation
Chapters 26: Urinary System
(Figure 26.4)