Circulation: The Heart and Blood Vessels Chapter 7.
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Transcript of Circulation: The Heart and Blood Vessels Chapter 7.
Circulation: The Heart and Blood Vessels
Chapter 7
Be Not Still, My Beating Heart!
Heart: most durable muscle Sudden cardiac arrest treatment:• Cardiopulmonary resuscitation (CPR)
• Automated external defibrillator (AED)
7.1 The Cardiovascular System: Moving Blood through the Body
Focus: The cardiovascular system is built to rapidly transport blood to
every living cell in the body.
The Heart and Blood Vessels Make up the Cardiovascular System
Cardiovascular system• Heart – main pumping organ • Blood vessels types:• Arteries• Arterioles• Capillaries• Capillary beds• Venules• Veins
The Heart and Blood Vessels Make Up the Cardiovascular System
Animation: Major human blood vessels
The Cardiovascular System Helps Maintain Favorable Operating Conditions
Last week
Blood Circulation Is Essential to Maintain Homeostasis
Major role in homeostasis• brings oxygen, nutrients, and hormones to cells• removes waste products from cells and excess
heat
The Cardiovascular System Is Linked to the Lymphatic System
Lymphatic system:• Pick up excess extracellular fluid and usable
substances• Return them to the cardiovascular system
7.2 The Heart: A Double Pump
Focus: In a lifetime of 70 years, the human heart beats some 2.5 billion times.
This durable pump is the centerpiece of the cardiovascular system.
The Heart
Located in the center of your chest Composed of myocardium • Cardiac muscular middle layer
Protected by the pericardium• Outermost layer
Smooth lining of endocardium • Inner layer
The Heart Is Divided into Right and Left Halves
KNOW THIS DIAGRAM!
Animation: The human heart
The Heart Has Two Halves and Four Chambers
Septum: thick wall divides heart in half Chambers of the heart:• Left and Right Atrium• Left and Right Ventricle
Valves:• Atrioventricular: • Tricuspid (right side) and bicuspid (left side)
• Semilunar Coronary arteries: branch off of the aorta• Delivers blood & oxygen to the heart
The Heart Is Divided into Right and Left Halves
The Heart Itself Is Served by Coronary Arteries and Veins
In a Heartbeat, the Heart’s Chambers Contract, Then Relax
Heartbeat: one cycle of contraction and relaxation of the heart chambers
Cardiac cycle• Systole: contraction• Diastole: period of time when the heart fills with
blood after systole • Relaxation
• “Lub-dup” sound Cardiac output • Every 60 seconds ~5 liters/ventricle
The Heart Beats in a Sequence Called the Cardiac Cycle
Animation: Cardiac cycle
7.3 The Two Circuits of Blood Flow
Focus: Each half of the heart pumps blood.
The two side-by-side pumps are the basis of two cardiovascular circuits through the body, each with its own set of arteries, arterioles,
capillaries, venules, and veins.
In the Pulmonary Circuit, Blood Picks Up Oxygen in the Lungs Pulmonary Circuit:• Carries oxygen-depleted blood away from the
heart, to the lungs, and returns oxygenated blood back to the heart.
• Lungs and heart only • Pulmonary arteries: deoxygenated blood to
lungs• Pulmonary veins: oxygenated blood to heart
Each Half of the Heart Pumps Blood in a Different Circuit
In the Systemic Circuit, Blood Travels to and from Tissues
Systemic circuit • Oxygenated blood pumped by left side of heart
moves through body and returns to left atrium• Heart and the rest of the body
Aorta• Main vessel out of the left ventricle• Major arteries branch off this
Superior vena cava• Main route of blood from head to heart
Inferior vena cava• Major route of blood from lower body to heart
Each Half of the Heart Pumps Blood in a Different Circuit
Animation: Human blood circulation
Blood from the Digestive Tract Detours to the Liver for Filtration.
7.4 How Cardiac Muscle Contracts
Focus: Unlike skeletal muscle, which contracts only when orders arrive from the nervous system, cardiac muscle contracts—and
the heart beats– spontaneously.
Electrical Signals from “Pacemaker” Cells Drive the Heart’s Contractions
Cardiac muscle have:• Intercalated discs: communication junctions
between cardiac muscle cells• Ensures rapid electrical conduction through heart
Cardiac conduction system: independent of the nervous system• Sinoatrial (SA) node: cardiac pacemaker• Atrioventricular (AV) node:
Intercalated Discs Form Communication Junctions between Cardiac Muscle Cells
The Cardiac Conduction System
Animation: Cardiac conduction
7.5 Blood Pressure
Focus: Heart contractions generate blood pressure, which
changes as blood moves through the cardiovascular system.
Blood Exerts Pressure against the Walls of Blood Vessels
Blood pressure: fluid pressure that blood exerts against vessel walls
Systolic (ventricular contraction) and diastolic pressure (ventricular relaxation): • Normal: 120/80
Hypertension• Chronically elevated blood pressure
Hypotension• Abnormally low blood pressure
Animation: Measuring blood pressure
Cholesterol types
High Density Lipoproteins (HDL)• remove cholesterol from within arteries• transport it back to the liver for excretion or re-
utilization• they are seen as "good" lipoproteins
Low Density Lipoproteins (LDL)• carry cholesterol in the blood and around the body,
for use by cells• commonly referred to as "bad cholesterol" due to
the link between high LDL levels and cardiovascular disease
Blood Pressure Values (mm of Hg)
A Variety of Factors May Cause Hypertension
Is this you?
7.6 Structure and Functions of Blood Vessels
Focus: As with all body parts, structure is key to the functions of blood vessels.
All our vessels transport blood, but there are important differences in how different kinds manage blood flow and
blood pressure.
Arteries Are Large Blood Pipelines
Outer layer: • Mainly collagen
Middle layer: • Smooth muscle and elastin
Innermost layer:• Thin sheet of endothelium
Carries oxygenatedblood away from heart
Blood Pressure Changes as Blood Flows through the Cardiovascular System
Take pulse fromarteries because of the strong pressure
Arterioles Are Control Points for Blood Flow
Wall built of smooth muscle rings over elastic tissue• Dilates when smooth muscle relaxes• Constricts when smooth muscle contracts
Offer more resistance to blood flow than other vessels do
Capillaries Are Specialized for Diffusion
Thinnest wall of any blood vessel!• Single layer of flat endothelium
Site of diffusion of gases, nutrients, and wastes Extensive!• 62,000 miles long
Blood pressure drops slowly as blood flows through
Venules and Veins Return Blood to the Heart
Venules • Function somewhat like capillaries
Veins• Large diameters and low-resistance transport of
blood back to the heart• Outer layer of connective tissue • Middle layer of smooth muscle and elastic fibers• Inner layer of endothelium• Valves prevent backflow of blood• varicose veins: valves don’t function properly
Contracting Skeletal Muscles Can Increase Fluid Pressure in a Vein
Animation: Vein function
Animation: Vessel anatomy
Vessels Help Control Blood Pressure
Medulla• Monitors resting blood pressure• Vasodilation• Vasoconstriction
Baroreceptor reflex• Keeps blood pressure within normal limits in the
face of sudden changes• Baroreceptors found in the carotid arteries in the
neck and in the arch of the aorta
7.7 Capillaries: Where Blood Exchanges Substances with
Tissues
Focus: Blood enters the systemic circulation moving swiftly in the aorta, but this speed has to slow in order for
substances to move into and out of the bloodstream.
A Vast Network of Capillaries Brings Blood Close to Nearly All Body Cells
40 billion capillaries Every cell is a diffusible distance away from a
capillary Blood flow is slowest in the capillaries
Many Substances Enter and Leave Capillaries by Diffusion
Diffusion of fluids and solutes across the porous capillary walls• Blood flows through the capillaries very slowly to
allow this exchange
Some of the Substances Pass through Pores in Capillary Walls
Fluid movement in capillaries:• Bulk flow• Role of lymphatic vessels• Captures excess fluid from circulatory system
Help maintain blood pressure
Animation: Capillary forces
Blood in Capillaries Flows Onward to Venules
Capillaries branch into capillary beds Precapillary sphincter• Ring of smooth muscle• Regulates the flow of blood into the capillary
7.8 Cardiovascular Disease
Major Risk Factors for Cardiovascular Disease
Arteries Can Clog or Weaken
Atherosclerosis• fatty material collects along the walls of arteries.
This fatty material thickens, hardens (forms calcium deposits), and may eventually block the arteries.• All adults should keep their LDL ("bad") cholesterol
levels below 130-160 mg/dL.
Plaques and Blood Clots May Clog Arteries
Risk factors for atherosclerosis include:Diabetes
Heavy alcohol useHigh blood pressure
High blood cholesterol levelsHigh-fat diet
Increasing ageObesity
Personal or family history of heart diseaseSmoking
Arteries Can Clog or Weaken
Coronary arteries• Narrow and vulnerable to clogging by plaques• Angina pectoris• medical term for chest pain or discomfort due to
coronary heart disease
• “Plaque-busting” drugs: statins • Ways to repair coronary blockage:• Coronary bypass• Laser angioplasty• Balloon angioplasty
• Aneurysm
Heart Damage Can Lead to Heart Attack and Heart Failure
Heart attack• Damage or death to cardiac muscle• Warning signs: • Chest discomfort• Discomfort in other areas of the upper body• Shortness of breath• cold sweat, nausea, or light-headedness
• Risk factors
Heart Failure• Weak heart and ineffective pump
Arrhythmias Are Abnormal Heart Rhythms
Electrocardiogram (ECG)• Recording of the electrical activity of the cardiac
cycle
Arrhythmias: irregular heart rhythms• Bradycardia: slower than normal heart rate• Tachycardia: faster than normal heart rate• Ventricular fibrillation: rapid, erratic electrical
impulses
Animation: Examples of ECGs
7.9 Infections, Cancer, and Heart Defects
Focus: Infections may seriously damage the heart.
Myocarditis: is an inflammation of the myocardium, the middle layer of the heart wall
various causesBacterial
Alcohol abuse
Drug abuse
Heart Damage May Be a Complication of Lyme Disease
Is There Such a Thing as Heart Cancer?
Rarely the first site for cancer
Can be a secondary site
Chemotherapy and/or radiation can damage the heart and blood vessels
Inborn Heart Defects Are Fairly Common
“Blue babies”
Heart does not pump blood efficiently
How is the problem corrected?