Cardiovascular SystemCardiovascular System

I. Functions of the heart.I. Functions of the heart.

1. Generating blood pressure.1. Generating blood pressure.

2. Routing blood.2. Routing blood.

3. Ensuring blood moves one way.3. Ensuring blood moves one way.

4. Regulating blood supply.4. Regulating blood supply.

Cardiovascular SystemCardiovascular System

II. HeartII. HeartA. General CharacteristicsA. General Characteristics

1. 100,000 time/day1. 100,000 time/day

2. 4,00L/day = 1,000 2. 4,00L/day = 1,000 gallonsgallons

3. 60,000 miles of 3. 60,000 miles of blood vesselsblood vessels

4. Center of the 4. Center of the circulatory Systemcirculatory System

5. Center of the 5. Center of the Thoracic Cavity, Thoracic Cavity, between the lungsbetween the lungs

6. 2/3 on the left side6. 2/3 on the left side

7. Decreases in size 7. Decreases in size after the age of 65.after the age of 65.

B. Coverings of the heartB. Coverings of the heart1. Pericardium - covers the heart, 2 main 1. Pericardium - covers the heart, 2 main

layerslayersa. Parietal Cardium (pericardial sac)a. Parietal Cardium (pericardial sac)

••OuterOuter••Loose fittingLoose fitting

1. Fibrous - Outer, thick, 1. Fibrous - Outer, thick, tough tough dense connective dense connective tissue.tissue.

Protects & anchors to the Protects & anchors to the diaphragmdiaphragm

2. Serous - Inner, thin, 2. Serous - Inner, thin, Squamous Squamous epitheliumepithelium

b. Visceral Pericardium (Epicardium)b. Visceral Pericardium (Epicardium)

••Attaches to the surface of Attaches to the surface of the the heartheart

••Considered to be the outer Considered to be the outer most most layer of the heart.layer of the heart.

c. Pericardial Cavityc. Pericardial Cavity••Space filled with fluidSpace filled with fluid••LubricationLubrication••Percarditis - swelling of Percarditis - swelling of

spacespace

C. Heart WallsC. Heart Walls3 layers - middle is the most 3 layers - middle is the most

important - Myocardiumimportant - Myocardium

1.1. Epicardium - Thin Epicardium - Thin protective barrier of the protective barrier of the heartheart

Serous membraneSerous membraneFat depositsFat deposits

2. Myocardium -Bulk of the 2. Myocardium -Bulk of the heartheart

Fibrous skeleton - bundles Fibrous skeleton - bundles of connective tissueof connective tissueLayer that contractsLayer that contracts

3. Endocardium- Inner most 3. Endocardium- Inner most layerlayerSmooth white layerSmooth white layer Squamous epitheliumSquamous epithelium

D. Heart ChambersD. Heart ChambersSuperiorSuperior1.1. Atria - Receiving chambers Atria - Receiving chambers

for bloodfor blood

Min. role in pumpingMin. role in pumping

Pectinate Muscles - ridges Pectinate Muscles - ridges of muscleof muscle

Interatrial Septum - Interatrial Septum - separates the atrium into separates the atrium into right & left halvesright & left halves

Fossal Ovalis - oval Fossal Ovalis - oval depression of the heart depression of the heart believed to be an opening believed to be an opening in the fetal heartin the fetal heart

a. Right Atrium - a. Right Atrium - receives receives from the vena from the vena cavacava

b. Left Atrium receives b. Left Atrium receives from from the lungsthe lungs

InferiorInferior

2. Ventricles - forces blood 2. Ventricles - forces blood through the bodythrough the body

Trabeculae Carnae - Trabeculae Carnae - Irregular folds of muscle in Irregular folds of muscle in the endocardiumthe endocardium

Papillary muscles - Slender Papillary muscles - Slender projections off of the projections off of the trabuclae carnaetrabuclae carnae Attaches to valves & Attaches to valves &

aids in functionaids in function

Interventricular Septum - Interventricular Septum - Separates ventricles into Separates ventricles into left & right halvesleft & right halves

Coronary Sulcus - Externally Coronary Sulcus - Externally separates the atrium & separates the atrium & ventriclesventricles

E. Heart valvesE. Heart valvesBlood flows in one directionBlood flows in one directionPrevents back flowPrevents back flow

1. Atrioventricular valves (AV) - 1. Atrioventricular valves (AV) - between atrium & ventriclesbetween atrium & ventricles

2 or 3 triangular flaps or 2 or 3 triangular flaps or cuspscusps

Point downward into the Point downward into the ventriclesventricles

Tricuspid between right Tricuspid between right Atrium & Atrium & ventricle (3 flaps)ventricle (3 flaps)

Bicuspid (mitral) between left Bicuspid (mitral) between left atrium & ventricle (2 flaps)atrium & ventricle (2 flaps)

Chordae tendinae - strands of Chordae tendinae - strands of connective tissue connective tissue

Anchors cusps to papillary walls of Anchors cusps to papillary walls of the ventriclesthe ventricles

Murmur - Cusps do not lose Murmur - Cusps do not lose completely - leaking of bloodcompletely - leaking of blood

2. Semilunar (SL) Valves2. Semilunar (SL) Valves

Between ventricles & blood leavingBetween ventricles & blood leaving

Pulmonary & AorticPulmonary & Aortic

3 half moon (semilunar) cusps3 half moon (semilunar) cusps

F. Blood flow through the F. Blood flow through the heartheart

G. Supply of blood to the heartG. Supply of blood to the heart

Coronary CirculationCoronary Circulation

Right & Left Coronary Arteries - carries fresh oxygenated Right & Left Coronary Arteries - carries fresh oxygenated blood blood (70% of oxygen, only 25% to skeletal muscles, increases to (70% of oxygen, only 25% to skeletal muscles, increases to 70% 70% during exercise)during exercise)

Great & Small cardiac veinGreat & Small cardiac vein

Coronary Sinus - large vein that collects blood leaving the Coronary Sinus - large vein that collects blood leaving the heartheart

II. Heart Physiology - Pumps blood through out the body

A. Cardiac Cycle - contraction of both the atria & then ventricle.

1. Systole - Contraction2. Diastole - Relaxation

B. Heart Sounds - LUB - DUB Closing of the heart valves

1. Lub - Closing of the AV valves2. Dub - Closing of the Sl valves

C. Heart Conduction - Each cardiac cycle is stimulated by special conducting cells in the heart.

1. Receives a signal form the autonomic nervous system.

2. Sinoatrial (SA) Node “Pacemaker” - cluster of pace setting cells

Initiates each cardiac cycle by generating an electric impulse.

Spread quickly through out the atrium.

Stimulates the second cluster of cells.

3. Atrioventricular (AV) Node, AV. bundle, Bundle of His - relays the signal to the ventricles.

Extends down the septum of the heart.

4. Purkinje fibers - branches of the AV node, passes further into the myocardium.

5. If the SA node is unable to produce the electrical impulse for the heart to contract, the AV node functions as the pacemaker

6. Slower – Ectopic beat.

D. Electrocardiogram (ECG or EKG) - measures the electrical events during a cardiac cycle

1. Detect changes in the electrical changes in the heart wall

2. Electrical changes produces a changes in the ionic flow through out the body

SA node fires send action potential.

P Wave - depolarization of the atria - action potential.

QRS Wave - depolarization of the ventricle.

T Wave ventricular repolarization of the ventricle

PQ interval – atria contract & begins to relax.

QT interval – ventricle depolarizes & repolarizes.

E. Cardiac Output - Volume of blood pumped1. Heart rate X Stroke Volume = Cardiac

Output 75 bpm X 70 ml = 5250 ml/min

(5.25 L/min)

2. Adjustments - exerciseHeart rate

Stroke Volume

3. Starling’s Law - Further the heart is stretched, the stronger the contraction.

Preload – pressure on the heart when the ventricles are stretched when filling with blood.

Afterload – pressure the heart must beat against.

F. Regulation of Heart Activity 1. Controlled by the reflex center

(cardioregulatory center) - medulla oblongata.2. Baroreceptors - detect the blood pressure.3. Parasympathetic fibers from the medulla

oblongata through the Vagus nerve extends to the heart.

Acetylcholine (Ach) slows the heartNorepinephrine (NE) speed the heart up

Barorecptor relfex

G. Cardiac cycleThree major events in the cycle.1. Systole –

a. Blood is pushed towards the atria, closely the AV valves.

b. Pressure increases in the ventricle forcing the SL

valves to open.

2. Diastole –a. Pressure in the ventricles decrease, the AV valves

open and blood fills the ventricles up to 70% of their volume.

3. End-Atria relaxes & fills with

blood, then contract & starts it over.

Cardiac Cycle

III. AgingA. By 70 output is reduced by 30%, by 85 30%-60%.B. Hypertrophy is common (enlargement of left ventricle), due to increase afterload (high blood pressure).

Leads to decreased elasticity & increased stiffness.

Increased left atria pressure and cause pulmonary edema, feel out of breath.C. Greater amount of time to contract & relax leading to decreased in maxmium heart rate.D. Connective tissue with the valves becomes less flexible.E. Development of coronary artery disease in 10% of people over 80.

VI. Cardiovascular diseases

A. Congestive heart failure - failure of the heart to pump blood to the body tissues.

B. Heart Block – Failure of the SA or AV. to generate impulses.

C. Heart fibrillation - Heart beats at a irregular pace.

D. Heart flutter - heart race up to 300 bpm.

E. Hypertension - elevated blood pressure.

F. Murmur - Leaking of blood through a closed valve.

G. Myocarditis - infection of the heart muscle.

H. Pericarditis - Infection of the pericardial sac which results in thicken or scarring.

1. What are the three types of blood 1. What are the three types of blood vessels and how are they different?vessels and how are they different?

2. What is the difference between 2. What is the difference between vasodialation & vasoconstriction?vasodialation & vasoconstriction?

3. What are the 3 layers of the blood 3. What are the 3 layers of the blood vessels?vessels?

4. Does blood ever flow in reverse within 4. Does blood ever flow in reverse within the blood vessels?the blood vessels?