Circulation: The Heart and Blood Vessels

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Circulation The Heart and Blood Vessels

• Chapter 7

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Be Not Still, My Beating Heart!

• Heart most durable muscle
• Sudden cardiac arrest treatment
• Cardiopulmonary resuscitation (CPR)
• Automated external defibrillator (AED)

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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.

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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

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The Heart and Blood Vessels Make Up the
Cardiovascular System
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Animation Major human blood vessels
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The Cardiovascular System Helps Maintain
Favorable Operating Conditions
Last week
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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

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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

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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.

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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

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The Heart Is Divided into Right and Left Halves
KNOW THIS DIAGRAM!
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Animation The human heart
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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

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The Heart Is Divided into Right and Left Halves
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The Heart Itself Is Served by Coronary Arteries
and Veins
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In a Heartbeat, the Hearts 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

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The Heart Beats in a Sequence Called the Cardiac
Cycle
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Animation Cardiac cycle
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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.

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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

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Each Half of the Heart Pumps Blood in a Different
Circuit
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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

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Each Half of the Heart Pumps Blood in a Different
Circuit
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Animation Human blood circulation
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Blood from the Digestive Tract Detours to the
Liver for Filtration.
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7.4 How Cardiac Muscle Contracts

• Focus Unlike skeletal muscle, which contracts
  only when orders arrive from the nervous system,
  cardiac muscle contractsand the heart beats
  spontaneously.

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Electrical Signals from Pacemaker Cells Drive
the Hearts 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

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Intercalated Discs Form Communication Junctions
between Cardiac Muscle Cells
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The Cardiac Conduction System
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Animation Cardiac conduction
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7.5 Blood Pressure

• Focus Heart contractions generate blood
  pressure, which changes as blood moves through
  the cardiovascular system.

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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

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Animation Measuring blood pressure
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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

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Blood Pressure Values (mm of Hg)
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A Variety of Factors May Cause Hypertension
Is this you?
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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.

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Arteries Are Large Blood Pipelines

• Outer layer
• Mainly collagen
• Middle layer
• Smooth muscle and elastin
• Innermost layer
• Thin sheet of endothelium

Carries oxygenated blood away from heart
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Blood Pressure Changes as Blood Flows through the
Cardiovascular System
Take pulse from arteries because of the strong
pressure
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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

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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

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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 dont function properly

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Contracting Skeletal Muscles Can Increase Fluid
Pressure in a Vein
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Animation Vein function
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Animation Vessel anatomy
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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

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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.

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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

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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

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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

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Animation Capillary forces
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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

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7.8 Cardiovascular Disease
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Major Risk Factors for Cardiovascular Disease
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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.

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Plaques and Blood Clots May Clog Arteries
Risk factors for atherosclerosis
include Diabetes Heavy alcohol use High blood
pressure High blood cholesterol levels High-fat
diet Increasing age Obesity Personal or family
history of heart disease Smoking
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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

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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

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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

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Animation Examples of ECGs
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7.9 Infections, Cancer, and Heart Defects

• Focus Infections may seriously damage the
  heart.

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• Myocarditis is an inflammation of the
  myocardium, the middle layer of the heart wall
• various causes
• Bacterial
• Alcohol abuse
• Drug abuse

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Heart Damage May Be a Complication of Lyme Disease
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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

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Inborn Heart Defects Are Fairly Common

• Blue babies
• Heart does not pump blood efficiently
• How is the problem corrected?