RT 208 PERIPHERAL CIRCULATION ANATOMY AND PHYSIOLOGY

RT 208 PERIPHERAL CIRCULATION ANATOMY AND PHYSIOLOGY PREFI TOPIC BY YJV

Circulation 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

The pressure creates a pulse that can be felt, distinguishing them from veins.

Systemic arteries carry oxygenated blood away from the heart to the tissues

Since its oxygen rich, full of oxygen, normal systemic arterial blood is bright cherry red.

Arterial Blood

Bright red; lots of oxygen

Venous Blood

Dark red; lots of CO2

Pulmonary Artery

only artery that carries deoxygenated blood

It is part of the pulmonary circulation & carries deoxygenated blood from the heart to the lungs.

Systemic artery

Carry oxygenated blood away from the heart to the tissues

Since its oxygen rich, full of oxygen, normal systemic arterial blood is bright cherry red.

Arterioles

Smallest branch of arteries that join with the capillaries

Aorta

Largest artery in the body

Veins

Blood vessels that return blood towards the heart

Venules

smallest veins at the junction of the capillaries

Vena Cavae

Largest veins in the body

Great Saphenous Vein

Longest veins in the body

Runs the length of the leg

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 that connect the arterioles and venules

forms a bridge between the arterial and venous circulation

the blood is a mixture of both venous and arterial blood.

Spurting blood

Pulsating flow

Bright red color

Arteries

Steady, slow flow

Dark red color

Veins

slow, even flow

Capillaries

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 ______

1. Ensures that plasma & interstitial fluid (2 major components of extracellular fluid) are in constant communication

2. Accelerates distribution of nutrients, hormones, & dissolved gases throughout tissue

3. Assists in transport of insoluble lipids & tissue proteins that cannot enter circulation by crossing capillary wall

4. Has flushing action that carries bacterial toxins & other chemical stimuli to lymphoid tissues & organs responsible for providing immunity from disease

Important Functions:

1. Tunica Interna

2. Tunica Media

3. Tunica Externa

Walls of Arteries and Veins contain three distinct Layers:

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

Collagen fibers bind media to interna & externa

Commonly thickest layer in wall of small artery

Separated from surrounding externa by external elastic membrane: thin band of elastic fibers

Smooth muscle cells encircle endothelium lining of lumen of vessel

Tunica Externa

Outermost layer of vessel & forms connective tissue sheath around vessel

In arteries, this layer contains collagen fibers with scattered bands of elastic fibers

In veins, which is generally thicker than media, contains networks of elastic fibers & bundles of smooth muscle cells

1. Walls of arteries are thicker than veins

2. Tunica media of artery contains more smooth muscle & elastic fibers o These contractile & elastic components resist pressure generated by heart as it forces blood into circuit

3. When not opposed by blood pressure, elastic fibers in arterial walls recoil, constricting lumen so arterial walls on slide look smaller than veins, but they retain circular shape

4. Veins’ do not retain circular shape

5. Endothelial lining of artery cannot contract, its endothelium, is thrown into folds that give arterial sections a pleated appearance, lining of vein lacks these folds

Difference between Arteries and Veins:

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:

• Pressure decreases

• Flow decreases

• Resistance increases

As blood flows from the aorta toward the capillaries and from capillaries toward the vena cava:

Vasoconstriction

Decreases the size of the lumen

Vasodilation

Increases the size of the lumen

Capillary bed

Capillaries form networks called ______

pre-capillary sphincter

Blood flow through the capillary is regulated by ______

band of smooth muscle that guards entrance to each capillary

neither tunica media nor externa

Capillaries has ________

Continuous Capillary

Fenestrated Capillary

Sinusoidal Capillary

Capillaries has two basic structures:

Continuous Capillary

Complete lining

Supply most region of body

Can be found in all tissues except epithelial and cartilage

Least permeable, most common (skin and muscle)

Fenestrated Capillary

Contain windows (pores) that span endothelial lining

Permit rapid exchange of large solutes

Occurs in areas of active absorption or filter (kidneys, small intestine

Sinusoidal Capillary

specialized fenestrated capillaries that are flattened and irregular

blood moves through sinusoids relatively slowly, maximizing time available for absorption and secretion across sinusoidal walls

most permeable

occurs in special locations (liver, bone marrow, adrenal glands, spleen)

High pressure

pressure of arteries

Low pressure

pressure of veins

Venules

Medium-sized veins

Large veins

Veins are classified according to their size into:

Venules and medium sized veins

contains valves

Valve

prevent backflow of blood

Superficial vein

- 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

Deep Vein

- 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

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

Swollen, knotted superficial veins

Visual Inspection

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

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

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:

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

Skin Preparation

Asepsis is vital when performing venipuncture as the skin is breached and a foreign device is introduced into a sterile circulatory system.

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

Inability to obtain specimen due to:

• Poor technique

• Pressure not being applied to puncture site following removal of needle

FORMATION OF HEMATOMA

• If an artery is punctured: release the tourniquet, remove the needle and apply firm pressure for a minimum of 5 minutes

• Cover the site with a dressing once bleeding has stopped. Re-check for signs of bleeding in 20 minutes.

Puncture of an Artery: