Cardiovascularvessels.ppt

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Cardiovascular: Blood

Vessels

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 Blood vessels _{Blood vessels}

distribute oxygenated

blood throughout the

body to all of its

tissues and returns

unoxygenated blood

back to the heart.

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 Arteries_Arteries – the vessels _{– the vessels} that carry the blood

that carry the blood

away from the heart;

usually arteries carry

oxygenated blood.

 Veins _Veins- The vessels _{- The vessels} that return the blood to

that return the blood to

the heart; usually carry

unoxygenated blood.

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Flow of Blood through the vessels



As the blood is carried away, the arterial

system branches into smaller and smaller

vessels until it reaches the capillaries.



The

capillaries

are the point of oxygen

exchange, where the blood drops off the

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 There are capillaries _{There are capillaries} present in all body

present in all body

tissues.

 After the blood leaves _{After the blood leaves} the capillary, it enters

the capillary, it enters

a system of veins that

branch into larger

vessels until the blood

returns to the heart.

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I. Structure

A.

A. ArteriesArteries

1. Three layers of tissue (deep to superficial) 1. Three layers of tissue (deep to superficial)

a. Inner layer – endothelium – simple squamous a. Inner layer – endothelium – simple squamous b. Middle layer – smooth muscle and elastic fibers b. Middle layer – smooth muscle and elastic fibers c. Outer layer – elastic and collagen fibers

c. Outer layer – elastic and collagen fibers

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B. Arterioles

1.

1. Two layers of tissue Two layers of tissue

(inside out)

a. Inner layer – thin

layer of endothelium

b. Outer layer – few

smooth muscle

fibers

2. Lumen – microscopic

space

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C. Capillaries

1.

1. Layer of tissueLayer of tissue

a.

a. Single layer of Single layer of

epithelium

connected to a

basement

membrane

b.

b. Precapillary Precapillary Sphincter

Sphincter –ring of –ring of muscle at the

muscle at the

beginning of the

capillary

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D. Venules

1.

1. Layer of tissueLayer of tissue

-Thin layer of endothelium near the capillaries

that gets thicker the closer they get to the

veins.

2. Lumen – microscopic opening

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E. Veins

1.

1. Three layers of tissue (inside out)Three layers of tissue (inside out)

a. Inner layer – endothelium – simple

squamous. In veins, the endothelium folds

inwards and makes a valve.

b. Middle layer – smooth muscle and elastic

fibers; this layer is thinner than the middle of

an artery

c. Outside layer – elastic and collagen fibers

2. Lumen – opening in the middle; wider than the

lumen of arteries because there is less muscle.

Animation of Venous Valve

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Blood Pressure Physiology

 Blood Pressure (BP) by definition is the _{Blood Pressure (BP) by definition is the}

pressure exerted by blood on the wall of the

vessel.

I.

I. Blood Flow – amount of blood that flows Blood Flow – amount of blood that flows

through a vessel during a given time.

A. Types of blood flow

1. Pulmonary Circulation – blood

flows to the lungs and picks up oxygen and

expels carbon dioxide

2. Systemic flow – blood delivers

oxygen and picks up carbon dioxide from the

rest of the body

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B. Factors that determine blood

flow

1.

1. Blood Pressure (see Blood Pressure (see

previous)

a. Direct relationship with

blood flow; so as the

pressure goes up, so does

the blood flow

b. Blood flows from an area

of high pressure to an area

of low pressure

2. Resistance – friction

between the blood and the

walls of the vessel; makes

it harder for blood to flow

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2 Factors that Contribute to

Resistance

a.

a. Blood viscosity – Blood viscosity –

thickness of blood

b.

b. Blood vessel radius Blood vessel radius

– smaller radius =

more resistance

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Arterial Blood Pressure (ABP)

 Blood pressure by _{Blood pressure by} clinical definition is

clinical definition is

the pressure within

the arteries. We will

call this arterial blood

pressure (ABP)

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II. Factors that affect ABP

A.

A. Cardiac output – amount of blood ejected by Cardiac output – amount of blood ejected by

ventricle/minute

>Direct relationship

1. As the cardiac output increases, the

BP increases

B.

B. Blood Volume – amount of blood in Blood Volume – amount of blood in

cardiovascular system

>Direct relationship

1. As the volume increases, the blood

pressure increases

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III. Regulators of blood pressure

A.

A. Vasomotor CenterVasomotor Center

-Bundle of Sympathetic Nerves

in the cardiovascular center

in the brain

1.

1. Controls diameter of blood Controls diameter of blood

vessels by sending impulses

and creating

vasoconstriction

a. Increase the impulses

sent by the vasomotor and

vasoconstriction increases.

b. Decrease the impulses

and the vasoconstriction

decreases.

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B. Baroreceptors

- Pressure sensor

located on the large

arteries like the aorta.

•

• Controls the BP by Controls the BP by sending messages to

sending messages to

the sympathetic or

parasympathetic

nerves.

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1.

When the BP increases, the

baroreceptors send more impulses to the

cardiovascular center (CC) in the brain,

and the parasympathetic nerves

decrease the heart rate.

2.

When the BP decreases, the

baroreceptors send fewer impulses to

the CC and the sympathetic nerves

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C. Chemoreceptors – receptors

sensitive to chemicals



Regulates the level of oxygen and carbon

dioxide by sending messages to the

vasomotor center.

1. When the oxygen levels are too low and

the carbon dioxide levels are too high, the

chemoreceptors send impulses to the

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D. Hormones

1.

Epinephrine - A hormone secreted by the

adrenal medulla that is released into the

bloodstream in response to physical or

mental stress (fight or flight response will

increase BP).

2.

ADH (Antidiuretic Hormone) – a

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E. Auto Regulators – response

independent of vasomotor

1.

Heat causes vasodilation

2.

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Capillary Exchange and Venous

Return

I.

Capillary exchange – exchange of

materials at the capillaries

A. Pressures that regulate exchange

(movement of materials)

1. Hydrostatic – pressure of

blood within capillaries

2. Osmotic – pressure of the

fluid moving between tissues

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B. Processes of Exchange

1.

1. Filtration – movement of fluids out of the Filtration – movement of fluids out of the

capillaries into the interstitial tissues (arterial

end)

2.

2. Reabsorption – movement of fluids from the Reabsorption – movement of fluids from the

interstitial tissues into the capillaries

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II. Venous Return – blood returning

to the heart through the veins



Factors that affect the return

A. Pumping action of the heart

1. Pressure – higher in the veins so

flows towards R Atrium

2. Ventricular Contraction – creates

sucking action

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B. Velocity of the blood flow

1. Slows in the capillaries for exchange

2. Speeds up when the blood reaches the

veins

C. Muscles and valves – prevents back flow

of blood

1. Muscles contract and the valves open

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>This cycle creates

pressure that propels

blood towards the

heart. The cycle is

called

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D. Breathing



Changes in pressure in the different

cavities affect blood flows. For example,

when you breath, the thoracic cavity

increases in volume and decreases in

pressure. The abdominal cavity does the

opposite; blood flows from high to low

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Circulation

I.

I. Systemic Systemic

Circulation

>Circulation of

blood from the

heart to the rest of

the body or

system, and then

back to the heart

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Oxygenated Blood

1.

1. Starts at the heartStarts at the heart

2.

2. Aorta – all system arteries branch off the aortaAorta – all system arteries branch off the aorta

3.

3. Ascending aorta – the head, neck, and arm Ascending aorta – the head, neck, and arm

arteries branch off

4.

4. Arch of AortaArch of Aorta

5.

5. Descending AortaDescending Aorta

6.

6. Abdominal Aorta – the arteries of the digestive Abdominal Aorta – the arteries of the digestive

system branch off

7.

7. Common Iliac Arteries – branches off of the Common Iliac Arteries – branches off of the

abdominal aorta and continues down legs

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Deoxygenated Blood

8. The blood returns via

the systemic veins

that run parallel to the

systemic arteries

9. These systemic veins

drain into the superior

vena cava, inferior

vena cava, or the

coronary sinus that

delivers the blood

back to the heart.

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II. Cerebral Circulation



The delivery of blood to and away from

the brain

1.

Once the blood reaches the brain it

enters an arrangement of blood vessels

at the base of the brain called the

cerebral arterial circle (Circle of Willis)

2.

From here the arteries branch off to

anterior and posterior cerebral arteries.

Communicating arteries connect the

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III. Hepatic Portal System

 System that returns the unoxygenated blood _{System that returns the unoxygenated blood} from the gastrointestinal tract to the heart

from the gastrointestinal tract to the heart

1.

1. The blood from the digestive organs drains into The blood from the digestive organs drains into

the hepatic (liver) portal vein.

2.

2. The joining of the splenic vein and the superior The joining of the splenic vein and the superior

mesenteric veins forms the hepatic portal vein.

3.

3. The blood from the “portal” enters the liver. The blood from the “portal” enters the liver.

The liver filters out the excess materials from

the blood and stores them. The liver also

removes waste from the blood and detoxifies

the blood.

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Animation of Venous ValveAnimation of Venous Valve