Chapter 7
Biology 25: Human Biology
Prof. Gonsalves
Los Angeles City College
Loosely Based on Mader’s Human
Biology,7th edition
Blood Vessels

Include arteries, arterioles, capillaries, venules, and veins.

Double circuit, closed system:
1. Pulmonary circuit: Delivers blood to lungs. Oxygenation
of blood.
2. Systemic circuit: Delivers oxygenated blood to tissues and
organs of body (brain, liver, heart, kidneys, etc). Picks up
carbon dioxide produced by tissues.
Heart
Anatomical Features:




Hollow muscular organ, about the size of a human
fist.
Weighs less than one pound (10 ounces).
Rests on diaphragm, near middle of thoracic cavity.
Wall is composed of cardiac muscle covered by
connective tissue.
Pericardium: Membrane that surrounds entire heart and
contains a fluid which protects heart and decreases friction.
Heart
Heart Chambers: Heart is divided into four
separate chambers. Both the left and the right
side of the heart have a(an):

Atrium (Plural atria): Smaller, superior
chambers. Receive blood from veins.

Ventricle: Larger, inferior chambers.
Pump blood into arteries.
Two sides of heart have different functions:

Right side: Pumps oxygen poor blood.

Left side: Pumps oxygen rich blood.
Pacemaker (Sinoatrial node): Specialized structure
that sends electrical impulses that causes both
atria and ventricles to contract.
Heart
Heart Valves: Heart has several valves made of connective
tissue, that prevent backflow of blood as it circulates.
 Atrioventricular (AV) Valves: Close between atria and
ventricles
 Right AV Valve: Connects right atrium to the right
ventricle.
 Left AV Valve: Connects left atrium to the left
ventricle.
 Semilunar Valves: Close as blood leaves the ventricles
and enters the arteries.
Heart murmur: Rushing, gurgling sound created by
backflow of blood due to damaged or imperfect heart
valves. Fairly common (10% of healthy population).
Most are asymptomatic.
Heart Beat

Average 70 beats per minute.

100,000 beats every day.

Cardiac cycle about every 0.8 sec.

Diastole: Heart relaxes and blood flows into chambers (0.4 sec).

Systole: Heart contracts.

First atria (0.1 sec)

Then ventricles (0.3 sec)

Pumps about 8000 liters of blood/day.

Pacemaker (Sinoatrial node): Controls heart rate.



Regulated by nervous and endocrine systems.
Two heart beat sounds (“Lub-dupp”):

First sound: Ventricles contract, AV valves close.

Second sound: Heart relaxes, semilunar valves are closing.
Pulse: Arteries expand and contract with each heartbeat.
Pacemaker Controls Cardiac Rhythm
Blood Pressure

Pressure is highest in arteries; lowest in veins.

“Blood pressure” usually refers to arterial pressure.

Usually measured at brachial artery in arm.

Two measurements:

Systolic Blood Pressure: During heart
contraction. Normal systolic pressure is about
120 mm Hg.
(Range: 110-140 mm Hg).

Diastolic Blood Pressure: During heart
relaxation. Normal diastolic pressure is about
80 mm Hg.
(Range: 70-90 mm Hg)
Blood Pressure and Velocity in Blood Vessels
Blood Pathway in Body


Right Side of Heart:

Right atrium receives oxygen poor blood from body.

Right ventricle pumps oxygen poor blood to lungs.
Left Side of Heart:

Left atrium receives oxygenated blood from lungs.

Left ventricle pumps oxygenated blood to body.
Blood Pathway:
Veins ---> Vena cava ---> Right atrium ---> Right ventricle --->
Pulmonary artery ---> Lungs ---> Left atrium ---> Left
ventricle --->
Aorta ---> Arteries ---> Capillaries ---> Veins
Cardiovascular Disease

Number one cause of death in the U.S. and industrialized
nations.

Includes hypertension, strokes, heart attacks, and congestive
heart failure.

Most often caused by complications of: Arteriosclerosis: A
condition in which arteries become blocked by calcium and
lipid deposits (plaque), losing their elasticity.
Heart Attack (Myocardial infarction-MI)

Sudden decrease in blood supply to the heart, due to a
clot or plaque in arteries.

Death of cardiac muscle resulting in insufficient blood
supply to rest of body.

Heart may stop beating altogether or suffer permanent
damage.

Over 1.3 million heart attacks every year in U.S.

Leading cause of death and disability

60% had no previous symptoms.

25% are not recognized when they occur.

25% die before receiving medical assistance.

In 1995 960,000 deaths in U.S.
Heart Attacks are Caused by Blocked
Coronary Arteries
Heart Attack (Myocardial infarction)

Symptoms: Chest pain, pressure, or tightness, sweating,
nausea, shortness of breath, dizziness, and fainting.

Risk factors:
 Smoking
 High blood pressure
 High cholesterol
 High LDLs (low density lipoproteins)
 Diabetes
 Male gender
 Emotional stress
 Obesity
 Heredity
 Sedentary lifestyle
Hypertension: High blood pressure.

Blood pressure over 140/90.

Over 20% of U.S. population suffers from blood
pressures over 160/95.

Another 25% is borderline (above 140/90).

Heart must work harder to overcome resistance.

Silent killer: May have few or no symptoms.

May result in strokes, heart attacks, aneurysms,
ischemia (insufficient blood supply to heart) and
arteriosclerosis.

Risk factors: Heredity, obesity, high salt intake, black
race (relative risk 2), smoking, stress, diet high in fat,
and lack of exercise.
Ischemic Heart Disease:

Insufficient blood supply to the heart.

Especially during exercise or physical exertion.

May cause angina pectoris: sharp chest pain.
Congestive Heart Failure:

Heart cannot pump enough blood to meet body’s
needs.

Slow blood flow causes veins to back up causing
edema in tissue (legs, tissues, or lungs).

Symptoms: Shortness of breath, edema, and fatigue.

Causes: Hypertension , arteriosclerosis, heart valve
damage, heart attack, etc.
Stroke:

Third leading cause of death in U.S. after heart disease and
cancer.

5% of people over 65 have had a stroke.

400,000 stroke victims discharged from hospitals every year.

Insufficient blood supply to the brain, caused by a blood clot or
rupture of a blood vessel.

Depending on area affected may cause:

Paralysis (usually one side of body).

Loss of sensation or motor control.

Incontinence

Loss of speech, hearing, or sight.

Death