Download Cardiovascular System

Cardiovascular System
BLOOD VESSELS
Blood Vessels
  Delivery system of dynamic structures
  Closed system
  Arteries
  Carry
 
blood away from the heart
Capillaries
  Contact
 
tissue cells and directly serve cellular needs
Veins
  Carry
blood toward the heart
Venous system
Large veins
(capacitance
vessels)
Small veins
(capacitance
vessels)
Postcapillary
venule
Thoroughfare
channel
Arterial system
Heart
Large
lymphatic
vessels
Lymph
node
Lymphatic
system
Elastic arteries
(conducting
vessels)
Muscular arteries
(distributing
vessels)
Arteriovenous
anastomosis
Lymphatic
capillary
Sinusoid
Arterioles
(resistance vessels)
Terminal arteriole
Metarteriole
Precapillary sphincter
Capillaries
(exchange vessels)
Figure 19.2
Common
carotid arteries
to head and
subclavian
arteries to
upper limbs
Capillary beds of
head and
upper limbs
Superior
vena cava
Aortic
arch
Aorta
RA
LA
RV
Inferior
vena
cava
LV
Azygos
system
Thoracic
aorta
Venous
drainage
Arterial
blood
Capillary beds of
mediastinal structures
and thorax walls
Diaphragm
Abdominal
aorta
Inferior
vena
cava
Capillary beds of
digestive viscera,
spleen, pancreas,
kidneys
Capillary beds of gonads,
pelvis, and lower limbs
Figure 19.20
Tissue Layers
  Tunica interna
  Tunica media
  Tunica externa
Tunica intima (interna)
• Endothelium
• Subendothelial layer
Internal elastic lamina
Tunica media
(smooth muscle and
elastic fibers)
External elastic lamina
Valve
Tunica externa
(collagen fibers)
Lumen
Artery
(b)
Capillary
network
Lumen
Vein
Basement membrane
Endothelial cells
Capillary
Figure 19.1b
Vein
Artery
(a)
Figure 19.1a
Arteries of the head and trunk
Internal carotid artery
External carotid artery
Common carotid arteries
Vertebral artery
Subclavian artery
Brachiocephalic trunk
Aortic arch
Ascending aorta
Coronary artery
Thoracic aorta (above
diaphragm)
Celiac trunk
Abdominal aorta
Superior mesenteric artery
Renal artery
Gonadal artery
Common iliac artery
Inferior mesenteric artery
Internal iliac artery
(b) Illustration, anterior
view
Arteries that supply
the upper limb
Subclavian artery
Axillary artery
Brachial artery
Radial artery
Ulnar artery
Deep palmar arch
Superficial palmar arch
Digital arteries
Arteries that supply
the lower limb
External iliac artery
Femoral artery
Popliteal artery
Anterior tibial artery
Posterior tibial artery
Arcuate artery
Figure 19.21b
Arteries
  Transport blood from left ventricle to body tissues
  High pressure
  Three groups
  Elastic (conducting)
  Muscular (distributing)
  Arterioles (resistance)
Table 19.1 (1 of 2)
Elastic Arteries
  Conducting arteries
  Large and thick-walled
  Near the heart
  Aorta and major branches
  Large lumen = low resistance
  Expand during systole and recoil during diastole
Muscular Arteries
  Distributing arteries
  Distal to elastic arteries
  Deliver blood to body organs
  Thick tunica media with more smooth muscle
  Active in vasoconstriction
  Examples
  Radial, femoral, brachial
Resistance Arteries
  Smallest arterial vessels
  Lead to capillary beds
  Control valves to capillary beds
  Site of most vasodilation and vasoconstriction
Table 19.1 (1 of 2)
Metarterioles are modified capillaries
Precapillary
sphincters
Vascular shunt
Metarteriole
Thoroughfare channel
True capillaries
Terminal arteriole
Postcapillary venule
(a) Sphincters open—blood flows through true capillaries.
Terminal arteriole
Postcapillary venule
(b) Sphincters closed—blood flows through metarteriole
thoroughfare channel and bypasses true capillaries.
Figure 19.4
Capillaries
Capillary beds
 
 
Microcirculation between arterioles and venules
Two types
 
1. 
Continuous
1. 
2. 
3. 
2. 
Open junctions between adjacent endothelial cells
Most common
In skin and muscles
Fenestrated
1. 
2. 
Pores = permeable
Intestines, endocrine organs, kidneys
21_01e
Precapillary
sphincters
Vascular shunt
Metarteriole
Thoroughfare channel
True capillaries
Terminal arteriole
Postcapillary venule
(a) Sphincters open—blood flows through true capillaries.
Terminal arteriole
Postcapillary venule
(b) Sphincters closed—blood flows through metarteriole
thoroughfare channel and bypasses true capillaries.
Figure 19.4
Capillaries
  Precapillary sphincters
  Local chemical conditions
  Vasomotor nerves
Continuous Capillaries
  Abundant in the skin and muscles
  Tight junctions connect endothelial cells
  Intercellular clefts allow the passage of fluids and small solutes
  Continuous capillaries of the brain
  Tight junctions are complete, forming the blood-brain barrier
  Blood Brain Barrier
Figure 19.22c Arteries of the head, neck, and brain.
Copyright © 2010 Pearson Education, Inc.
Pericyte
Red blood
cell in lumen
Intercellular
cleft
Endothelial
cell
Basement
membrane
Tight junction
Pinocytotic
Endothelial
vesicles
nucleus
(a) Continuous capillary. Least permeable, and
most common (e.g., skin, muscle).
Figure 19.3a
Pinocytotic
vesicles
Red blood
cell in lumen
Fenestrations
(pores)
Endothelial
nucleus
Intercellular
cleft
Basement membrane
Tight junction
Endothelial
cell
(b) Fenestrated capillary. Large fenestrations
(pores) increase permeability. Occurs in special
locations (e.g., kidney, small intestine).
Figure 19.3b
Endothelial
cell
Red blood
cell in lumen
Large
intercellular
cleft
Tight junction
Nucleus of
Incomplete
endothelial
basement
cell
membrane
(c) Sinusoidal capillary. Most permeable. Occurs in
special locations (e.g., liver, bone marrow, spleen).
Figure 19.3c
Capillaries
  Functions
  Exchange area for blood and interstitial fluid compartment
  Diffusion
  O2
and nutrients from the blood to tissues
  CO2 and metabolic wastes from tissues to the blood
Pinocytotic vesicles
Red blood
cell in lumen
Endothelial cell
Endothelial cell nucleus
Basement membrane
Tight junction
Fenestration
(pore)
Intercellular cleft
Figure 19.16 (1 of 2)
Veins
  Functions
  Collect blood from capillary beds
  “drain” organs and tissues of blood
  Become larger as they come closer to the heart
Veins of the head and trunk
Dural venous sinuses
External jugular vein
Vertebral vein
Internal jugular vein
Right and left
brachiocephalic veins
Superior vena cava
Great cardiac vein
Hepatic veins
Splenic vein
Hepatic portal vein
Renal vein
Superior mesenteric
vein
Inferior vena cava
Inferior mesenteric vein
Veins that drain
the upper limb
Subclavian vein
Axillary vein
Cephalic vein
Brachial vein
Basilic vein
Median cubital vein
Ulnar vein
Radial vein
Digital veins
Veins that drain
the lower limb
External iliac vein
Femoral vein
Great saphenous vein
Common iliac vein
Popliteal vein
Internal iliac vein
Posterior tibial vein
Anterior tibial vein
(b) Illustration, anterior
view. The vessels of the
pulmonary circulation
are not shown.
Small saphenous vein
Dorsal venous arch
Dorsal metatarsal veins
Figure 19.26b
Venules
  Formed when capillary beds unite
  Very porous
  Allow fluids and WBC’s into tissues
Pulmonary blood
vessels 12%
Systemic arteries
and arterioles 15%
Heart 8%
Capillaries 5%
Systemic veins
and venules 60%
Copyright © 2010 Pearson Education, Inc.
Figure 19.5
Veins
  Thinner walls, larger lumens than arteries
  Blood pressure is lower than in arteries
  Thin tunica media and a thick tunica externa
  Capacitance vessels (blood reservoirs)
  Contain up to 65% of the blood supply
Vein
Artery
(a)
Figure 19.1a
Venous Blood Pressure
  Low pressure
  Due to cumulative effects of peripheral resistance
  Effect of gravity?
  Valves
  Skeletal muscle and action
  Thoracic pressure changes
Valve (open)
Contracted
skeletal
muscle
Valve (closed)
Vein
Direction of
blood flow
Figure 19.7
Varicose Veins
  Incompetent valves
  Pregnancy
  Obesity
  Long periods of standing
  Hemorrhoids
Blood Flow
  Blood flow is involved in
  O2 delivery
  Removal of wastes
  Gas exchange (lungs)
  Absorption of nutrients (digestive tract)
  Urine formation (kidneys)
Blood Flow
  Perfusion
  Rate of blood flow per given volume of tissue
  Blood flow (F)
  Volume of blood flowing through a vessel, an organ,
or tissue in a given period
 Measured as ml/min
 Varies widely through individual organs
  Based on needs
F= ΔP/R
Blood Flow
• 
F= Δ P/R
o  F = Blood flow
o  ΔP = Difference in pressure between two points
o  R = Resistance
Blood Flow
  Relationship between blood flow, blood pressure,
and resistance
If ΔP increases, blood flow speeds up
  If R increases, blood flow decreases
 
  R is more important in influencing local blood flow
  Changed by altering blood vessel diameter
Blood Pressure
  Blood pressure (BP)
  Force per unit area exerted on the wall of a blood vessel by the
blood
  Typically expressed as the height of a column of mercury (mm
Hg)
  P = H x D
Blood Pressure
  Factors influencing blood pressure
  Cardiac output (CO)
  Peripheral resistance (PR)
  Blood volume
Blood Pressure
  Systolic pressure
  Pressure exerted during ventricular contraction
  Top number
  Diastolic pressure
  Lowest level of arterial pressure
  Bottom number
  Average value = 120/80
  Pulse pressure
  Difference between systolic and diastolic pressure
Systolic pressure
Mean pressure
Diastolic
pressure
Copyright © 2010 Pearson Education, Inc.
Figure 19.6
Blood Pressure
  Basic concepts
  The pumping action of the heart generates blood flow
  Pressure results when flow is opposed by resistance
  Systemic pressure
  Highest
in the aorta
  Declines throughout the pathway
  Is 0 mm Hg in the right atrium
  The steepest drop occurs in arterioles
Systolic pressure
Mean pressure
Diastolic
pressure
Figure 19.6
Arterial Blood Pressure
  Reflects two factors of the arteries close to the heart
  Elasticity
  Volume of blood forced into them at any time
  Blood pressure near the heart is pulsatile
Arterial Blood Pressure
  Mean arterial blood pressure (MABP)
  Pressure that propels blood to tissues
  Represents average blood pressure
MABP = diastolic pressure + 1/3 pulse pressure
  Pulse pressure and MAP both decline with
increasing distance from the heart
Hypertension
  “Silent Killer”
  Resting systolic >140 mm Hg and/or diastolic >90 mm Hg
  Causes
  Loss of flexibility in vessel walls
  Results
  Heart failure
  Renal failure
  Stroke
  Increased risk of aneurysm
Capillary Blood Pressure
  Not pulsatile
  Low capillary pressure is desirable
  High BP would rupture fragile, thin-walled capillaries
  Most are very permeable, so low pressure forces filtrate into
interstitial spaces
Systolic pressure
Mean pressure
Diastolic
pressure
Copyright © 2010 Pearson Education, Inc.
Figure 19.6
Peripheral Resistance
  The opposition to blood flow exerted by vessel walls
  The result of friction
  Influenced by 3 factors
  Blood viscosity
  Blood vessel length
  Blood vessel radius
Peripheral Resistance
Blood viscosity
 
 
 
Albumin
Erythrocytes
Peripheral Resistance
  Vessel length
  The father fluid travels = more cumulative friction
Peripheral Resistance
  Vessel radius
  Most significant factor
  Vasoconstriction and vasodilation
  Flow is proportional to fourth power of radius
  Alteration
of radius profoundly affects blood flow
  Examples…
Poiseuille’s Law
  Formula representing the factors influencing flow
F = ΔPπr4/ 8 nL
F= flow
ΔP = pressure gradient
r4 = vessel radius
n = viscosity
L = vessel length
Poiseuille’s Law
  Blood flow is directly proportional to pressure
gradient and vessel radius
  Blood flow is inversely proportional to vessel length
and blood viscosity
F = ΔPπr4/ 8 nL
Questions?
  Homework #1: Artery Labeling
  Due in lab!