Peripheral Circulation and Anatomy

The Circulatory system

System of blood vessels that, along with the heart,

form the closed systems by which blood is

circulated to all parts of the body.

Pulmonary circulation

Carries blood from the RV of the heart to the lungs

to remove carbon dioxide & pick up oxygen and

returns oxygenated blood to the LA of the heart

Systemic circulation

Serves the rest of the body, carrying oxygenated

blood and nutrients from the LV of the heart to the

body cells & returning to the RA of the heart with

blood that is carrying carbon dioxide & other waste

products of metabolism from the cells.

Blood vessels

Tube-like structures capable of expanding and

contracting

- Arteries

- Veins

- Capillaries

3 types of blood vessels

Arteries

• Blood vessels that carry blood away from the

heart.

• Thick walled

Systemic arteries

carry oxygenated blood away

from the heart to the tissues.

bright cherry red

Since its oxygen rich, full of oxygen, normal

systemic arterial blood is ...

Lots of CO2

Venous blood is dark red due to ...

Lots of oxygen

Arterial blood is bright red due to ...

Pulmonary artery

only artery that carries

deoxygenated blood

Arterioles

Smallest branches of arteries that join

with the capillaries

Aorta

Largest artery in the body

Veins

• Blood vessels that return blood towards the

heart

• Carries deoxygenated blood except for the

pulmonary vein, which carries oxygenated

blood from the lungs back to the heart

Venules

Smallest veins at the junction of the capillaries

Vena Cavae

largest veins in the body

Great Saphenous veins

- longest veins in the body

- runs the length of the leg

- superficial vein

Superficial vein

to carry blood from the tissues

near the skin's surface in your feet and legs to the

deep veins.

Capillaries

• Microscopic

• One-cell-thick vessels connect the

arterioles & venules

• Forms a bridge between the arterial &

venous circulation

capillary level

Vital functions of cardiovascular system

depend entirely on events at ...

capillary walls

All chemical & gaseous exchange between

blood & interstitial fluid takes place across

...

Tunica Interna

• Innermost layer of blood vessel

• Includes endothelial lining & underlying layer of

connective tissue with variable number of elastic

fibers

internal elastic membrane

In arteries outer margin of interna contains thick layer

of elastic fibers called ...

Tunica Media

• Middle layer containing concentric layers of

smooth muscle tissue in framework of

connective tissue

• Commonly thickest layer in wall of small

artery

Tunica Externa

• Outermost layer of vessel & forms connective

tissue sheath around vessel

Arteries

In ..., the Tunica Externa layer contains collagen fibers

with scattered bands of elastic fibers

veins

In ..., Tunica Externa which is generally thicker than media,

contains networks of elastic fibers & bundles

of smooth muscle cells

• Have thicker walls

• Have more smooth muscle and elastic fibers

• More resilient

COMPARED TO VEINS, ARTERIES:

1. Elastic arteries

2. Muscular arteries

3. Arterioles

4. Capillaries

5. Venules

6. Medium veins

7. Large veins

BLOOD FLOWS THROUGH THE BLOOD VESSELS

FROM THE HEART AND BACK TO THE HEART IN

THE FOLLOWING ORDER:

o Pressure decreases

o Flow decreases

o Resistance increases

As blood flows from the aorta toward the

capillaries and from capillaries toward the vena

cava:

Vasoconstriction

Decrease the size of the lumen

Vasodilation

Increase size of the lumen

pre-capillary sphincter

o Blood flow through the capillary is regulated

by ...

capillary bed

Capillaries form networks called ...

Precapillary sphincter

band of smooth

muscle that guards entrance to each

capillary

Continuous capillary

o Have complete lining

o Supply most region of body

o Can be found in all tissues except

epithelial and cartilage

o Least permeable, most common (skin &

muscle)

Fenestrated capillary

o Contain windows (pores) that span

endothelial lining

o Permit rapid exchange of large solutes

o Occurs in areas of active absorption or filtration

(kidneys, small intestine)

sinusoids

Flattened fenestrated capillaries =

Sinusoidal capillary

o specialized fenestrated capillaries that are

flattened & irregular

o most permeable

slowly

o blood moves through sinusoids relatively

..., maximizing time available for

absorption & secretion across sinusoidal walls

- liver

- bone marrow

- adrenal glands

- spleen

Sinusoidal capillaries occur in special locations such as:

Veins

Collects blood from all tissues and organs and

return it to the heart

o Venules

o Medium-sized veins

o Large veins

Veins are classified according to their size into:

Valves

prevent backflow of blood

valves

Venules and medium-sized veins contain ...

Directly related

Pressure inside the arteries and patients blood pressure relationship

High pressure

Pressure in arteries

Low pressure

Pressure in veins

Superficial veins

- show considerable individual variation

- subcutaneous in the fasciae and are easily

palpable

Cephalic vein

in the dorsal venous network on the

dorsum of the hand (radial aspect)

Basilic vein

in the dorsal venous network and

ascends along the posterior ulnar side of the wrist

Median vein

drains the palmar venous arch

- Cephalic vein

- Basilic vein

- Median vein

Superficial veins examples;:

Deep veins

- accompany arteries

- usually in pairs on either side of the artery

and are connected by short crosslinks

- not advised for use for routine IV access

due to their close proximity to arteries and

veins

Radial vein

Run alongside the radial artery

Ulnar vein

Run alongside the ulnar artery

- Radial vein

- Ulnar vein

Examples of deep veins:

Aneurysm

A localized dilation or bulging in the wall of a

blood vessel, usually an artery

Arteriosclerosis

Thickening, hardening, and loss of elasticity

of artery walls

Atherosclerosis

A form of arteriosclerosis involving changes

in the intima of the artery due to accumulation

of lipids and so on

Embolism

Obstruction of a blood vessel by an embolus

Embolus

Air, mass of undissolved matter circulating in

the bloodstream

Hemorrhoids

Varicose veins in the rectal area

Phlebitis

Inflammation of a vein

Thrombophlebitis

Inflammation of a vein along with thrombus

(blood clot) formation

Thrombus

A blood clot in a blood vessel

Varicose veins (Varices)

swollen, knotted superficial veins

1. Visual inspection

2. Palpation

Vein selection

Visual inspection

The scrutiny of the veins in both arms

is essential prior to choosing a vein

Palpation

o Determines the location and condition of

the veins

o Distinguishes veins from arteries

and tendons

o Identifies the presence of valves

7 - 8 cm

The tourniquet should be placed about ...

above the venipuncture site

Application of a tourniquet

Promotes venous distension

Opening and closing of the fist

The muscles will force blood into the veins and

encourages distension. However, this action

may affect certain blood results, e.g. potassium

Light tapping of the vein

May be useful but can be painful and may result

in the formation of a hematoma in patients with

fragile veins

The use of heat

In the form of warm pack to encourage

vasodilatation and venous filling

1. APPLICATION OF A TOURNIQUET

2. OPENING AND CLOSING OF THE FIST

3. LIGHT TAPPING OF THE VEIN

4. THE USE OF HEAT

5. LOWERING THE ARM BELOW THE LEVEL OF

THE HEART

Ways on Improving venous access:

1. Arm on side of Mastectomy

2. Edematous areas

3. Hematomas

4. Arm in which blood is being transfused

5. Scarred areas

6. Arms with fistulas or vascular grafts

7. Sites above an IV cannula

INAPPROPRIATE SITE FOR VENIPUNCTURE

Asepsis

Skin preparation: ... is vital when performing venipuncture

as the skin is breached and a foreign device is

introduced into a sterile circulatory system.

Skin cleaning

is a controversial subject, and

it is acknowledged that a cursory wipe with an

alcohol swab does more harm than good as it

disturbs the skin flora

1. Inappropriate choice of vein

2. Thrombosed vein (due to previous or repeated

attempts)

3. Inexperience of operator

4. Patient shocked, cold or dehydrated causing

vasoconstriction

Complications

Inability to obtain specimen due to:

• Poor technique

• Pressure not being applied to puncture site

following removal of needle

FORMATION OF HEMATOMA DUE TO

5

If an artery is punctured: release the tourniquet,

remove the needle and apply firm pressure for

a minimum of ... minutes

20

Puncture of an artery:

Cover the site with a dressing once bleeding has

stopped. Re-check for signs of bleeding in ...

minutes.