Blood Flow
p. 717
Venous Valves & Larger Lumens
p. 715
Skeletal muscles “milk” veins
p. 726
Measuring BP
p. 684
BP is…
Systolic…
Diastolic…
Hypertension (HTN)
May be based on…
If Systolic = 120-139
Or if Diastolic = 80-89
Then “Prehypertension”
If Systolic = 140-159
Or if Diastolic = 90-99
Then “Stage 1 HTN”
Hypertension (HTN)
If Systolic = 160+
or if Diastolic = 100+
Then “Stage 2 HTN”
Dangers of Hypertension:
Atherosclerosis, stroke, MI, aneurysm,
kidney damage, blindness
Symptoms & Signs:
Usually none
Possible headaches & blurred vision
Hypotension
Criteria:
Systolic <100 or Diastolic <60
And symptomatic
S&S:
Weak, dizzy, light-headed,
lethargic, weak pulse
Lymphatic System
Lymphatic System
pillaries
• Endothelium: one cell thick
– Continuous
– Fenestrated
• Basement membrane
Capillaries
Figure 15-16: Types of capillaries
Veins and Venules (Contrasted to Arteries)
• Thinner walls
• Larger diameter
• Closer to skin
• Less muscle
• Less elastic
Figure 15-3: Metarterioles
Angiogenesis: Growth of New
Blood Vessels
• Normal body maturation and growth
• Endometrium
• Endurance training
• Abnormal growth to service cancerous
tissue
• Wound repair and consequences
– Failure to regrow in heart tissues after heart
attack
– Failure to regrow in brain after stroke
Special Interest
• Primary tumors secrete Anti-Angiogenic as
well as angiogenic agents
• Can be used in cancer chemotherapy
II. Blood Pressure
• Generated by Ventricular Contraction
• Pulsatile: surges in arteries
• Elastic rebound evens & maintains pressure
Blood Pressure
Figure 15-4: Elastic recoil in the arteries
Blood Pressure (BP):
Measurements
• "Blood pressure"
– Systolic over diastolic
– About 120/80 mmHg
• Sphygmomanometer
– "Estimate of pressure"
– Korotkoff sounds
Blood Pressure (BP): Measurements
Figure 15-7: Measurement of arterial blood pressure
More Blood Pressures:
Pulse and Mean Arterial
Pressures
• Pulse pressure = Systolic–Diastolic
• Mean arterial pressure (MAP) = Diastolic
+ 1/3 pulse pressure
Figure 15-5: Pressure throughout the systemic circulation
Factors Controlling MAP :
The Driving Pressure for Blood Flow
• Blood volume
• Cardiac output
• Resistance
• Distribution
Figure 15-10: Factors that influence mean arterial pressure
III. Arteriole Resistance: Control
of Local Blood Flow
• Myogenic auto regulation
• Paracrines:
– Active hyperemia
– Reactive hyperemia
• Sympathetic nerves – CNS
Arteriole Resistance: Control of Local
Blood Flow
Figure 15-11: Hyperemia
Tonic Control of Arteriole
Diameter
IV. Distribution of Blood in the
Body Organs
• Responds to metabolic need
• Precapillary sphincters
• Local & CNS regulators
• Huge variations (example: skeletal m 20-
85%)
Distribution of Blood in the Body
Organs
Figure 15-13: Distribution of blood in the body at rest
V. Capillary Exchange:
Greatest Total Cross Sectional Area
• Lowest Velocity
• Driving forces:
– Hydrostatic
pressure (drops)
– Colloidal osmotic
pressure
(constant)
Figure 15-17: The velocity of flow depends on the total cross-
sectional area
Types of Capillaries
Net Out Flow Into ECF
• Net filtration – net absorption = net out flow
• About 2 L/day collected by lymph vessels
Figure 15-18b: Fluid exchange at the capillary
VI. Lymphatic System: Structure and
Roles
• Lymphatic structures
– Capillaries with valves
– Lymph vessels
– Lymph nodes & organs
• Immune defense: lymphocytes
• Transport of fats
• Collects excess ECF
– Returns to plasma
– Edema
Lymphatic System: Structure and Roles
Figure 15-19: The lymphatic system
Elephantitis
• Causes:
• Roundworms from
mosquitoes
• Protozoan disease called
leishmaniasis
• Repeated streptococcal
infection
• the surgical removal of
lymph nodes
• a hereditary birth defect
VII. Regulation of Blood Pressure
• Control:
• Medullary cardiac control center
• Baroreceptor reflex
– Carotid
– Aortic
• Kidney: blood volume
• Hypothalamus & Cortex: stress, blushing,
etc.
Regulation of Blood Pressure
Figure 15-22: The baroreceptor reflex: the response to increased blood pressure
• Orthostatic
hypotension
VIII. Cardiovascular Diseases
• Risk Factors:
– Smoking
– Obesity
– Diabetes
– Genes
• Diseases:
– Hypertension
– Stroke
– "Heart Attack"
Mechanism of Atherosclerosis
• LDL build up
• Plaque
• Flow
• Rupture
• Clot
• Blocked flow
• Tissue death
Mechanism of Atherosclerosis
Figure 15-24: The development of atherosclerotic plaques
Mechanism of Atherosclerosis
Figure 15-24: The development of atherosclerotic plaques
Review
• I. Blood Vessels
• II. Blood Pressure
• III. Resistance in the Arterioles
• IV. Distribution of Blood to Tissues
• V. Capillary Exchange
• VI. Lymph Vessels
• VII. Blood Pressure and Circulation
• VIII. Cardiovascular Disease