BACNursingStudents



Chapter 14: Circulation and Blood Vessels Theory Lecture Outline

Objectives

1. Trace the path of cardiopulmonary circulation

2. Name and describe the specialized circulatory systems

3. Trace the blood in fetal circulation

4. List the types of blood vessels

5. Identify the principal arteries and veins of the body

6. Describe some disorders of the blood vessels

7. Define the key words that relate to this chapter

Blood Circulation

• Major circulatory systems

a. Cardiopulmonary circulation

o Blood from the heart to the lungs and back to the heart

b. Systemic circulation

o Blood from the heart to the tissues and cells and back to the heart

• Specialized circulatory systems

a. Coronary circulation

o Brings blood from the heart to the myocardium

b. Portal circulation

o Takes blood form the organs of digestion to the liver through the portal vein

c. Fetal circulation

o Only occurs in the pregnant female where the fetus obtains oxygen and nutrients from the mother’s blood.

Cardiopulmonary Circulation

• Takes Deoxygenated blood from the heart to the lungs where carbon dioxide is exchanged for oxygen; the oxygenated blood then returns to the heart

• Review of blood flow through the heart and lungs

o Right atrium → tricuspid valve → right ventricle → pulmonary valve → pulmonary arteries → arterioles → lungs (O2 and CO2 exchanged in the capillary beds) → venules → pulmonary veins → left atrium → bicuspid (mitral) valve → left ventricle → aortic valve → aorta → arteries →arterioles → capillaries (gas exchange) → venules → veins → superior and inferior vena cava

Systemic Circulation

• Functions

a. Circulates nutrients, oxygen, water, and secretions

b. Carries away waste products

c. Helps equalize body temperature

d. Aids in protecting the body from harmful bacteria

• The aorta and its branches

a. The aorta is the largest artery in the body

b. Branches

1. Coronary arteries – supplies the myocardium

2. Aortic arch – supplies the arms, neck and head

3. Descending Aorta – branches and supplies blood throughout the rest of the body

• Coronary Circulation

a. Brings oxygenated blood to the heart muscle

b. Right and left branches of the coronary artery

c. Exchange of oxygen and waste occurs at capillary level

d. Deoxygenated blood returns through the coronary veins to the coronary sinus

• Portal Circulation

a. A branch of the general circulation

b. Veins from the pancreas, stomach, small intestine, colon and spleen empty their blood into the hepatic portal vein which goes to the liver (hepatic refers to the liver)

c. Liver ensures that the blood’s glucose concentration is kept within a relatively narrow range

o Excess glucose is converted to glycogen for reserve storage

• Fetal Circulation

a. Occurs in the unborn baby (fetus)

b. Fetus obtains oxygen and nutrients from the mother’s blood; not through their own lungs and digestive systems

c. The fetal blood does not mix with the mother’s blood; the exchange of gases, food and waste is passed through the placenta

Blood Vessels

The heart pumps the blood to all parts of the body through a remarkable system of three types of blood vessels:

• Arteries

• Capillaries

• Veins

Arteries

• Carry oxygenated blood away from the heart to capillaries (exception – pulmonary arteries which carry deoxygenated blood from the heart to the lungs)

a. Thickness of the arteries make them the strongest of the three types of blood vessels

b. Transport blood under very high pressure (pulse)

c. Do not have valves

• Layers of the walls

a. Tunica adventitia or externa

b. Tunica media

c. Tunica intima

Mnemonic (recall hint) – “Add Me In”

• Aorta leads away from the heart and branches into smaller arteries

a. Smaller arteries branch into arterioles

b. Arterioles give rise to the capillaries

Capillaries

• Smallest blood vessels

• Can only be seen through a microscope

• Connect the arterioles and venules

• Muscle and connective tissue disappear and they become a simple endothelial cell layer

• Selective permeability of various cells and substances such as nutrient molecules, O2, CO2 and nitrogenous wastes

• Control of blood flow by precapillary sphincters

a. Not all capillaries are open simultaneously

b. Allows for regulation of blood flow to active tissues

Veins

• Carry deoxygenated blood away from the capillaries to the heart

• Layers of the walls

a. Tunica externa or adventitia

b. Tunica media

c. Tunica intima

• Walls much thinner than arteries

o Do not have to withstand as much pressure

• Veins have valves so blood flows in one direction

a. Toward the heart

b. Prevents reflux (backflow) of blood toward the capillaries

• Largest vein is the vena cavae

a. Superior vena cava returns blood from upper part of body

b. Inferior vena cava returns blood from the lower part of the body

Venous Return

• Valves help keep venous blood moving

• Skeletal muscles contract to push venous blood along its path

• Pressure changes occur when we breath which helps bring venous blood back to the heart

• Stationary positioning can decrease flow back to the heart for oxygenation

Blood Pressure

When the heart pumps blood into the arteries, the surge of blood filling the vessels creates pressure against their walls

• Systolic blood pressure

o Pressure measured at the moment of contraction

• Diastolic blood pressure

o Lessened force of the blood measured when the ventricles are relaxed

• Pulse pressure

o Difference between the systolic and diastolic (i.e. 120/80 has a pulse pressure of 40)

• Normal values

a. Systolic pressure averages 120 mm/Hg

b. Diastolic pressure averages 80 mm/Hg

c. Normal range 95/60 to 120/80

Pulse

A pulse is the alternating expansion and contraction of an artery as blood flows through it

• Can feel pulsating beat at certain points on the body

• Should be same as heart rate

• Can feel pulse on the body where the artery is near the surface of the skin and over a bone

o These are called pulse points

Pulse Points

• 7 paired locations

a. Brachial artery – located at the crook of the elbow along inner bicep muscle

b. Common carotid artery – located in the neck

c. Femoral artery – located in the inguinal or groin area

d. Dorsalis pedis artery – located on anterior surface of the foot

e. Popliteal artery- located behind the knee

f. Radial artery – located on the thumb side of wrist

g. Temporal artery – located slightly above the outer edge of the eye

• Pressure points can be used to stop bleeding distal to the pulse point

Congenital Heart Defects

• Occur when there is a malformation of the heart during fetal development

• Most common symptom

o Cyanosis - bluish discoloration to the skin and mucous membrane

• Microscopic surgery

o Can correct many congenital heart defects

Disorders of the Blood Vessels

• Aneurysm

o Ballooning out of an artery, accompanied by a thinning arterial wall, caused by a weakening of the blood vessel

• Arteriosclerosis

o Disease that occurs when the arterial walls thicken because of a loss of elasticity as aging occurs

• Atherosclerosis

o Disease that occurs when deposits of fatty substances form along the walls of the arteries

• Gangrene

o Death of body tissue due to an insufficient blood supply caused by disease or injury

• Phlebitis or thrombophlebitis

o Inflammation of the lining of a vein, accompanied by clotting of blood in the vein

• Embolism

o Traveling blood clot

• Varicose veins

o Swollen veins that result from a slowing of blood flow back to the heart

• Hemorrhoids

o Varicose veins in the walls of the lower rectum and the tissues around the anus

• Cerebral hemorrhage

o Bleeding form blood vessels within the brain

• Peripheral vascular disease

o Blockage of the arteries, usually in the legs

• Hypertension

High blood pressure often called the “silent killer” due to the asymptomatic nature of the disease

a. Normal

o Less than 120/80

b. Pre-hypertension

o 120-130/80-89

c. Stage I hypertension

o 140-159/90-99

d. Stage II hypertension

o 160 and above/100 and above

• White coat hypertension

o Increase in blood pressure due to stress when one is in a doctor’s office

• Hypotension

o Low blood pressure; usually the systolic reading is under 100 mm/Hg usually less than 90/60

• Transient ischemic attacks (TIAs)

o Temporary interruptions of the blood flow to the brain

• Cerebral vascular accident (CVA) Stroke

a. Sudden interruption of the blood supply to the brain

b. Causes impairment of the brain tissue and/or death

Hypoperfusion/ Shock

• Inadequate flow of blood carrying oxygen to the organs and body systems

• Hypoperfused tissue will stop working properly due to lack of O2

• Hypoperfusion leads to shock

o Body attempts to compensate for hypoperfusion by increasing respiratory rate, increasing the heart rate or sacrificing organs to protect blood flow to the brain

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