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Blood vessel lecture

Homework assignment

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Please turn to each neighbor and answer one of the following…

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B L O O D V E S S E L S

Cardiovascular System

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

Figure 19.2

Large veins (capacitance vessels)

Large lymphatic vessels

Arteriovenous anastomosis

Lymphatic capillary

Postcapillary venule

Sinusoid

Metarteriole

Terminal arteriole

Arterioles (resistance vessels)

Muscular arteries (distributing vessels)

Elastic arteries (conducting vessels)

Small veins (capacitance vessels)

Lymph node

Capillaries (exchange vessels)

Precapillary sphincter Thoroughfare channel

Lymphatic system

Venous system Arterial system Heart

Figure 19.20

Azygos

system

Venous

drainage

Arterial

blood

Thoracic

aorta

Inferior

vena

cava

Abdominal

aorta

Inferior

vena

cava

Superior

vena cava

Common

carotid arteries

to head and

subclavian

arteries to

upper limbs

Aortic

arch

Aorta

RA

RV LV

LA

Capillary beds of

head and

upper limbs

Capillary beds of

mediastinal structures

and thorax walls

Diaphragm

Capillary beds of

digestive viscera,

spleen, pancreas,

kidneys

Capillary beds of gonads,

pelvis, and lower limbs

Thought Question

Name several tissues or structures in the body that are avascular.

Blood Vessel Structure

Tissue layers

Tunica interna

Tunica media

Tunica externa

Figure 19.1b

Tunica media

(smooth muscle and elastic fibers)

Tunica externa

(collagen fibers)

Lumen

Artery

Lumen Vein

Internal elastic lamina

External elastic lamina

Valve

(b)

Endothelial cells Basement membrane

Capillary

network

Capillary

Tunica intima (interna)

• Endothelium • Subendothelial layer

Figure 19.1a

Artery

Vein

(a)

Figure 19.21b

Internal carotid artery

Common carotid arteries

Subclavian artery

Subclavian artery

Aortic arch

Ascending aorta

Coronary artery

Thoracic aorta (above diaphragm)

Renal artery

Superficial palmar arch

Radial artery

Ulnar artery

Internal iliac artery

Deep palmar arch

Vertebral artery

Brachiocephalic trunk

Axillary artery

Brachial artery

Abdominal aorta

Superior mesenteric artery

Gonadal artery

Common iliac artery

External iliac artery

Digital arteries

Femoral artery

Popliteal artery

Anterior tibial artery

Posterior tibial artery

Arcuate artery (b) Illustration, anterior

view

Inferior mesenteric artery

Celiac trunk

External carotid artery

Arteries of the head and trunk

Arteries that supply

the upper limb

Arteries that supply

the lower limb

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)

Arteries

Elastic arteries

Conducting arteries

Large & thick-walled

Near the heart

Aorta and major branches

Large lumen = low resistance

Expand during systole & recoil during diastole

Arteries

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

Arteries

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)

Figure 19.4

(a) Sphincters open—blood flows through true capillaries.

(b) Sphincters closed—blood flows through metarteriole

thoroughfare channel and bypasses true capillaries.

Precapillary

sphincters Metarteriole

Vascular shunt

Terminal arteriole Postcapillary venule

Terminal arteriole Postcapillary venule

Thoroughfare channel

True capillaries

Metarterioles are modified capillaries

Capillaries

Capillary beds

Microcirculation between arterioles & venules

Two types

1. Continuous

Open junctions between adjacent endothelial cells

Most common

In skin & muscles

2. Fenestrated

Pores = permeable

Intestines, endocrine organs, kidneys

21_01e

Figure 19.4

(a) Sphincters open—blood flows through true capillaries.

(b) Sphincters closed—blood flows through metarteriole

thoroughfare channel and bypasses true capillaries.

Precapillary

sphincters Metarteriole

Vascular shunt

Terminal arteriole Postcapillary venule

Terminal arteriole Postcapillary venule

Thoroughfare channel

True capillaries

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

Copyright © 2010 Pearson Education, Inc.

Figure 19.22c Arteries of the head, neck, and brain.

Figure 19.3a

Red blood

cell in lumen

Intercellular

cleft

Endothelial

cell

Endothelial

nucleus

Tight junction Pinocytotic

vesicles

Pericyte

Basement

membrane

(a) Continuous capillary. Least permeable, and

most common (e.g., skin, muscle).

Figure 19.3b

Red blood

cell in lumen

Intercellular

cleft

Fenestrations

(pores)

Endothelial

cell

Endothelial nucleus

Basement membrane

Tight junction

Pinocytotic

vesicles

(b) Fenestrated capillary. Large fenestrations

(pores) increase permeability. Occurs in special

locations (e.g., kidney, small intestine).

Figure 19.3c

Nucleus of

endothelial

cell

Red blood

cell in lumen

Endothelial

cell

Tight junction

Incomplete

basement

membrane

Large

intercellular

cleft

(c) Sinusoidal capillary. Most permeable. Occurs in

special locations (e.g., liver, bone marrow, spleen).

This is not in the Study Guide, just FYI

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

Veins

Functions

Collect blood from capillary beds

“drain” organs and tissues of blood

Become larger as they come closer to the heart

Figure 19.26b

Renal vein

Splenic vein

Basilic vein

Brachial vein

Cephalic vein

Dural venous sinuses

External jugular vein

Vertebral vein

Internal jugular vein

Superior vena cava

Right and left

brachiocephalic veins

Axillary vein

Great cardiac vein

Hepatic veins

Hepatic portal vein

Superior mesenteric

vein

Inferior vena cava

Ulnar vein

Radial vein

Common iliac vein

External iliac vein

Internal iliac vein

Digital veins

Femoral vein

Great saphenous vein

Popliteal vein

Posterior tibial vein

Anterior tibial vein

Small saphenous vein

Dorsal venous arch

(b) Illustration, anterior

view. The vessels of the

pulmonary circulation

are not shown. Dorsal metatarsal veins

Inferior mesenteric vein

Median cubital vein

Subclavian vein

Veins of the head and trunk Veins that drain

the upper limb

Veins that drain

the lower limb

Venules

Formed when capillary beds unite

Very porous

Allow fluids and WBC’s into tissues

Copyright © 2010 Pearson Education, Inc. Figure 19.5

Heart 8%

Capillaries 5%

Systemic arteries

and arterioles 15%

Pulmonary blood

vessels 12%

Systemic veins

and venules 60%

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 60% of the blood supply

Figure 19.1a

Artery

Vein

(a)

Venous Blood Pressure

Low pressure

Due to cumulative effects of peripheral resistance

Working against gravity

Valves

Skeletal muscle and action

Thoracic pressure changes

Figure 19.7

Valve (open)

Contracted

skeletal

muscle

Valve (closed)

Vein

Direction of

blood flow

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)

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

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 P 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 blood vessel by the blood

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

Copyright © 2010 Pearson Education, Inc. Figure 19.6

Systolic pressure

Mean pressure

Diastolic

pressure

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

Figure 19.6

Systolic pressure

Mean pressure

Diastolic

pressure

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 MABP 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

Copyright © 2010 Pearson Education, Inc. Figure 19.6

Systolic pressure

Mean pressure

Diastolic

pressure

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?

Due in Lab 1

PreLab 1

Homework #1: Artery Labeling

Due Tuesday 4/9

Homework #2: Vessel Chart