Chapter 7

Biology 25: Human BiologyBiology 25: Human Biology

Prof. GonsalvesProf. Gonsalves

Los Angeles City CollegeLos Angeles City College

Loosely Based on Mader’s Loosely Based on Mader’s Human Human BiologyBiology,7,7thth edition edition

Blood VesselsBlood Vessels Include arteries, arterioles, capillaries, venules, and veins.Include arteries, arterioles, capillaries, venules, and veins.

Double circuit, closed system:Double circuit, closed system:

1. Pulmonary circuit: 1. Pulmonary circuit: Delivers blood to lungs. Oxygenation Delivers blood to lungs. Oxygenation

of blood.of blood.

2. Systemic circuit: 2. Systemic circuit: Delivers oxygenated blood to tissues and Delivers oxygenated blood to tissues and

organs of body (brain, liver, heart, kidneys, etc). Picks up organs of body (brain, liver, heart, kidneys, etc). Picks up

carbon dioxide produced by tissues.carbon dioxide produced by tissues.

HeartHeartAnatomical Features:Anatomical Features:

Hollow muscular organ, about the size of a human Hollow muscular organ, about the size of a human fist.fist.

Weighs less than one pound (10 ounces).Weighs less than one pound (10 ounces). Rests on diaphragm, near middle of thoracic cavity.Rests on diaphragm, near middle of thoracic cavity. Wall is composed of cardiac muscle covered by Wall is composed of cardiac muscle covered by

connective tissue.connective tissue.PericardiumPericardium: Membrane that surrounds entire heart and : Membrane that surrounds entire heart and

contains a fluid which protects heart and decreases friction.contains a fluid which protects heart and decreases friction.

HeartHeartHeart ChambersHeart Chambers: Heart is divided into four : Heart is divided into four

separate chambers. Both the left and the right separate chambers. Both the left and the right side of the heart have a(an):side of the heart have a(an):

Atrium (Plural atria)Atrium (Plural atria): Smaller, : Smaller, superiorsuperior chambers. chambers. ReceiveReceive blood from veins. blood from veins.

VentricleVentricle: Larger, : Larger, inferiorinferior chambers. chambers. PumpPump blood into arteries. blood into arteries.

Two sides of heart have different functions:Two sides of heart have different functions:

Right sideRight side: Pumps oxygen poor blood.: Pumps oxygen poor blood. Left sideLeft side: Pumps oxygen rich blood.: Pumps oxygen rich blood.

Pacemaker (Sinoatrial node): Specialized structure that sends electrical impulses that causes both atria and ventricles to contract.

HeartHeartHeart ValvesHeart Valves: Heart has several valves made of connective tissue, : Heart has several valves made of connective tissue,

that prevent backflow of blood as it circulates.that prevent backflow of blood as it circulates. Atrioventricular (AV) ValvesAtrioventricular (AV) Valves: Close between atria and ventricles: Close between atria and ventricles

Right AV Valve:Right AV Valve: Connects right atrium to the right ventricle. Connects right atrium to the right ventricle. Left AV Valve:Left AV Valve: Connects left atrium to the left ventricle. Connects left atrium to the left ventricle.

Semilunar ValvesSemilunar Valves: Close as blood leaves the ventricles and enters : Close as blood leaves the ventricles and enters the arteries.the arteries.

Heart murmurHeart murmur: Rushing, gurgling sound created by backflow of : Rushing, gurgling sound created by backflow of blood due to damaged or imperfect heart valves. Fairly common blood due to damaged or imperfect heart valves. Fairly common (10% of healthy population). Most are asymptomatic.(10% of healthy population). Most are asymptomatic.

Heart BeatHeart Beat Average 70 beats per minute. Average 70 beats per minute. 100,000 beats every day.100,000 beats every day. Cardiac cycleCardiac cycle about every 0.8 sec. about every 0.8 sec.

DiastoleDiastole: Heart relaxes and blood flows into chambers (0.4 sec).: Heart relaxes and blood flows into chambers (0.4 sec). SystoleSystole: Heart contracts. : Heart contracts.

First atria (0.1 sec)First atria (0.1 sec) Then ventricles (0.3 sec)Then ventricles (0.3 sec)

Pumps about 8000 liters of blood/day.Pumps about 8000 liters of blood/day. Pacemaker (Sinoatrial node): Controls heart rate.Pacemaker (Sinoatrial node): Controls heart rate.

Regulated by nervous and endocrine systems.Regulated by nervous and endocrine systems. Two heart beat sounds (“Lub-dupp”):Two heart beat sounds (“Lub-dupp”):

First sound:First sound: Ventricles contract, AV valves close. Ventricles contract, AV valves close. Second soundSecond sound: Heart relaxes, semilunar valves are : Heart relaxes, semilunar valves are closingclosing..

PulsePulse: Arteries expand and contract with each heartbeat.: Arteries expand and contract with each heartbeat.

Pacemaker Controls Cardiac Rhythm

Blood PressureBlood Pressure

Pressure is highest in arteries; lowest in veins. Pressure is highest in arteries; lowest in veins.

““Blood pressureBlood pressure” usually refers to ” usually refers to arterialarterial pressure. pressure.

Usually measured at Usually measured at brachial arterybrachial artery in arm. in arm.

Two measurements:Two measurements:

Systolic Blood PressureSystolic Blood Pressure: During heart : During heart

contractioncontraction. Normal systolic pressure is about . Normal systolic pressure is about

120 mm Hg.120 mm Hg. (Range: 110-140 mm Hg). (Range: 110-140 mm Hg).

Diastolic Blood PressureDiastolic Blood Pressure: During heart : During heart

relaxationrelaxation. Normal diastolic pressure is about . Normal diastolic pressure is about

80 mm Hg.80 mm Hg.

(Range: 70-90 mm Hg)(Range: 70-90 mm Hg)

Blood Pressure and Velocity in Blood Vessels

Blood Pathway in BodyBlood Pathway in Body Right Side of HeartRight Side of Heart: :

Right atrium receives oxygen poor blood from body.Right atrium receives oxygen poor blood from body.

Right ventricle pumps oxygen poor blood to lungs. Right ventricle pumps oxygen poor blood to lungs.

Left Side of HeartLeft Side of Heart: :

Left atrium receives oxygenated blood from lungs.Left atrium receives oxygenated blood from lungs.

Left ventricle pumps oxygenated blood to body. Left ventricle pumps oxygenated blood to body.

Blood PathwayBlood Pathway::

Veins ---> Vena cava ---> Veins ---> Vena cava ---> Right atriumRight atrium ---> ---> Right ventricleRight ventricle ---> --->

Pulmonary artery ---> Lungs ---> Pulmonary artery ---> Lungs ---> Left atriumLeft atrium ---> ---> Left Left

ventricleventricle ---> --->

Aorta ---> Arteries ---> Aorta ---> Arteries ---> CapillariesCapillaries ---> Veins ---> Veins

Cardiovascular DiseaseCardiovascular Disease

Number one cause of death in the U.S. and industrialized Number one cause of death in the U.S. and industrialized

nations.nations.

Includes hypertension, strokes, heart attacks, and congestive Includes hypertension, strokes, heart attacks, and congestive

heart failure.heart failure.

Most often caused by complications of: Most often caused by complications of: ArteriosclerosisArteriosclerosis: A : A

condition in which arteries become blocked by calcium and condition in which arteries become blocked by calcium and

lipid deposits (lipid deposits (plaqueplaque), losing their elasticity.), losing their elasticity.

Heart Attack (Myocardial infarction-MI)Heart Attack (Myocardial infarction-MI)

Sudden decrease in blood supply to the heart, due to a Sudden decrease in blood supply to the heart, due to a

clot or plaque in arteries. clot or plaque in arteries.

Death of cardiac muscle resulting in insufficient blood Death of cardiac muscle resulting in insufficient blood

supply to rest of body. supply to rest of body.

Heart may stop beating altogether or suffer permanent Heart may stop beating altogether or suffer permanent

damage.damage.

Over 1.3 million heart attacks every year in U.S.Over 1.3 million heart attacks every year in U.S.

Leading cause of death and disabilityLeading cause of death and disability

60% had no previous symptoms. 60% had no previous symptoms.

25% are not recognized when they occur.25% are not recognized when they occur.

25% die before receiving medical assistance.25% die before receiving medical assistance.

In 1995 960,000 deaths in U.S. In 1995 960,000 deaths in U.S.

Heart Attacks are Caused by Blocked Coronary Arteries

Heart Attack (Myocardial infarction)Heart Attack (Myocardial infarction)

Symptoms:Symptoms: Chest pain, pressure, or tightness, sweating, Chest pain, pressure, or tightness, sweating,

nausea, shortness of breath, dizziness, and fainting.nausea, shortness of breath, dizziness, and fainting.

Risk factorsRisk factors:: SmokingSmoking High blood pressureHigh blood pressure High cholesterolHigh cholesterol High LDLs (low density lipoproteins)High LDLs (low density lipoproteins) DiabetesDiabetes Male genderMale gender Emotional stressEmotional stress ObesityObesity HeredityHeredity Sedentary lifestyleSedentary lifestyle

HypertensionHypertension: High blood pressure.: High blood pressure. Blood pressure over 140/90. Blood pressure over 140/90.

Over 20% of U.S. population suffers from blood Over 20% of U.S. population suffers from blood

pressures over 160/95. pressures over 160/95.

Another 25% is borderline (above 140/90).Another 25% is borderline (above 140/90).

Heart must work harder to overcome resistance.Heart must work harder to overcome resistance.

Silent killerSilent killer: May have few or no symptoms.: May have few or no symptoms.

May result in strokes, heart attacks, aneurysms, May result in strokes, heart attacks, aneurysms,

ischemia (insufficient blood supply to heart) and ischemia (insufficient blood supply to heart) and

arteriosclerosis. arteriosclerosis.

Risk factorsRisk factors: Heredity, obesity, high salt intake, black : Heredity, obesity, high salt intake, black

race (relative risk 2), smoking, stress, diet high in fat, race (relative risk 2), smoking, stress, diet high in fat,

and lack of exercise.and lack of exercise.

Ischemic Heart DiseaseIschemic Heart Disease:: Insufficient blood supply to the heart. Insufficient blood supply to the heart.

Especially during exercise or physical exertion. Especially during exercise or physical exertion.

May cause May cause angina pectorisangina pectoris: sharp chest pain.: sharp chest pain.

Congestive Heart FailureCongestive Heart Failure:: Heart cannot pump enough blood to meet body’s Heart cannot pump enough blood to meet body’s

needs.needs.

Slow blood flow causes veins to back up causing Slow blood flow causes veins to back up causing

edemaedema in tissue (legs, tissues, or lungs). in tissue (legs, tissues, or lungs).

SymptomsSymptoms: Shortness of breath, edema, and fatigue.: Shortness of breath, edema, and fatigue.

CausesCauses: Hypertension , arteriosclerosis, heart valve : Hypertension , arteriosclerosis, heart valve

damage, heart attack, etc.damage, heart attack, etc.

StrokeStroke:: Third leading cause of death in U.S. after heart disease and Third leading cause of death in U.S. after heart disease and

cancer.cancer.

5% of people over 65 have had a stroke.5% of people over 65 have had a stroke.

400,000 stroke victims discharged from hospitals every year.400,000 stroke victims discharged from hospitals every year.

Insufficient blood supply to the brain, caused by a blood clot or Insufficient blood supply to the brain, caused by a blood clot or

rupture of a blood vessel. rupture of a blood vessel.

Depending on area affected may cause:Depending on area affected may cause:

Paralysis (usually one side of body).Paralysis (usually one side of body).

Loss of sensation or motor control.Loss of sensation or motor control.

IncontinenceIncontinence

Loss of speech, hearing, or sight.Loss of speech, hearing, or sight.

Death Death