Cardiovascular System

Function

Circulate blood which delivers O2 & Nutrients to Tissues; Remove CO2 & Wastes

3 Components

1. Heart

2. Blood Vessels

3. Blood

2 Circulatory Pathways:

1. Pulmonary Circuit: The Movement of Oxygen - Poor (AKA Deoxygenated) Blood From Right Side of Heart to Lungs & Oxygen - Rich Blood Back to Heart

2. Systemic Circuit: Movement of Blood From Left Side of Heart to Body Tissues And Back

The Heart - Overview

1. It is Mostly a Muscle: Made of Cardiac Muscle Cells

2. Location: Thorax, In the Pericardial Cavity of Inferior Mediastinum

3. Regions:

a. APEX- The Pointed Bottom; Points Towards Left Hip

b. BASE- The Top; Points Towards Right Shoulder

The Heart - Coverings

1. Fibrous Pericardium: Tough, Dense CT

2. Serous Pericardium

a. Parietal Pericardium: Outermost Layer

b. Visceral Pericardium: (AKA Epicardium) - Lies Right On the Heart

c. Serous Fluid: In Between the 2

The Heart - WALLS of the Heart

1. Epicardium: Same as the Visceral Pericardium

2. Myocardium: Middle & Thickest Layer, Mostly Cardiac Muscle Tissue

3. Endocardium: Smooth Inner Layer, Made of Simple Squamous Epithelium

Anatomy Of The Heart - Quick Notes (Before Anatomy Diagram)

• Mammals have a 4 Chambered Heart

• 2 Atria=Receives Blood

• 2 Ventricles=Pump Blood Out

• The Chambers are Separated by 4 Valves

• 2 Atrioventricular Valves

• 2 Semilunar Valves

Anatomy Of The Heart & The Pathway Of Blood Diagram

1. Superior Vena Cava

Large Vein Carrying Deoxygenated Blood (Blood Low In O2 And High In CO2) From Upper Body

( Delivers To: Head, Neck, Arms, Chest )

2. Inferior Vena Cava

Large Vein Carrying Deoxygenated Blood From Lower Body

( Delivers To: Abdomen, Pelvis, Legs )

3. Right Atrium

Chamber That Receives Deoxygenated Blood From The Vena Cava

4. Tricuspid Valve (AKA Right A/V Valve)

Has 3 Cusps (Flaps)

Chordae Tendinae - Fibers That Anchor Cusps To Heart Wall (At The Papillary Muscle)

Hold Valve Flaps In Closed Position

5. Right Ventricle

Pumps Blood Into Pulmonary Circuit Via Pulmonary Arteries

6. Pulmonary Valve

A Semilunar Valve; Ensures Blood Goes To Lungs

7. Pulmonary Trunk

8. Pulmonary Arteries (Left & Right)

Takes Deoxygenated Blood To Lungs

9. Pulmonary Veins (Left & Right)

Brings Oxygenated Blood To Left Atrium

2 Pairs

10. Left Atrium

Chamber That Receives Oxygenated Blood From The 4 Pulmonary Veins

11. Mitral AKA Bicuspid Valve

AKA Left A/V Valve

Has 2 Cusps And Chordae Tendinae

12. Left Ventricle

Pumps Blood To Systemic Circuit

Walls Are Substantially Thicker

13. Aortic Valve

A Semilunar Valve Between Left Ventricle And Aorta

14. Aorta

Largest Artery In The Body

U Shaped

Descends Posteriorly To Heart

15. Interventricular Septum

Wall That Separates The Two Ventricles

4 Valves In Order Of How Blood Flows

1. Tricuspid Valve

2. Pulmonary Valve

3. Mitral Valve

4. Aortic Valve

Types of Blood Vessels - Arteries

Arteries - Blood Vessel that Carry Blood AWAY from Heart (Usually Oxygenated)

• Adapted for HIGH Pressure Blood Flow:

• Walls are Thicker With Muscle & Elastic Fibers (Recoil)

• NARROWER Diameter Lumen

• Smooth Muscles can DECREASE the Size of the Lumen to INCREASE Blood Pressure

• Lacks Valves - Which ALLOWS for Constant Flow

Types of Blood Vessels - Arterioles

Arterioles-

• Are Smaller Arteries

• Takes Oxygenated Blood To Capillaries

Types of Blood Vessels - Capillaries

Capillaries - Bridge Between Arteries & Veins

• Smallest Blood Vessels Where Gas Exchange Takes Place

• Adapted For Rapid Diffusion of Exchange of Materials

• Wall Is One Cell Thick = Short Diffusion Distance = Fast Diffusion of Substances

• Lumen Diameter is About The Size of One red Blood Cell = The Cell is Touching the Walls of the Capillary

• Blood Travels SLOWLY Under LOW Pressure

• The Walls can Contain Pores to Further Aid the Diffusion of Substances

• Capillary Bed - A Network Of Capillaries That Supplies A Whole Organ

Types of Blood Vessels - Venules & Veins

Veins - Any Blood Vessel that RETURNS Blood to the Heart

• Usually Carrying Deoxygenated Blood

1. Venule - A Small Vein That Drains The Capillary Bed

2. Veins

• Adapted For LOW Pressure Flow:

• Thinner - Walled

• Wider Diameter Lumen

• Have Valves - To Prevent Back Flow Of Blood = Ensures Blood Moves To Heart

• Skeletal Muscles Help Move Blood BACK to Heart

Blood Vessel Pathway

Arteries (Oxy. Blood) To Arterioles (Oxy. Blood) To Capillaries (Mix) To Venules (Deoxy. Blood) To Veins (Deoxy. Blood)

Compare & Contrast: Artery vs Vein vs Capillary

An Artery:

• Thick Outer Wall

• Small Lumen

• Thick Layer of Muscles & Elastic Fibers

A Vein:

• Fairly Thin Outer Wall

• Large Lumen

• Thin Layer Of Muscle & Elastic Fibers

A Capillary:

• Very Small Lumen

• Wall Made Of A Single Layer Of Cell

Major Arteries of the Human Body

• External Carotid (R) - Supplies Most of Face

• Internal Carotid (L) - Supplies Most of Brain

• Common Carotid (R)

• Common Carotid (L) - Take Pulse

• Right Bracheocephalic

• (L) Subclavian

• Axillary

• Brachial - Used For BP

• Renal Artery

• Abdominal Artery

• Radial - Used For Pulse

• Ulna

• Common Ilias

• External Ilias

• Femoral

Major Veins of the Human Body

• Jugular

• Bracheocephalic

• Subclavian

• Superior Vena Cava

• Inferior Vena Cava

• Renal

• Median Cubital - Typical Venipuncture Site

• Great Saphenous - Largest Vein In The Human Body

• Popliteal

The Aorta

• Aortic Arch

• Ascending Aorta

• R & L Coronary Arteries - These Supply Blood To The Heart Itself

• Descending Aorta - Goes Behind The Heart

Branched From L to R:

1. Brachiocephalic Trunk

2. Left Common Carotid Artery

3. Left Subclavian Artery

Cardiac Conduction System - A. Background

Myogenic - The Heart Generates Its Own Electrical Impulses (No Stimulation From Brain)

Myocardial Conduction Cells - Cells That Generate Or Conduct An Electrical Impulse AKA An Action Potential (AP)

Cardiac Conduction System - B. Steps To The Electrical Conduction System:

1. The Sinoatrial (SA) Node, AKA The Pacemaker, Initiates The Action Potential (Right Atrium)

2. The AP Spreads Through The Atria And Causes Them To Contract

3. The AP Goes To The Atrioventricular (AV) Node

4. After .1 Second Delay, AV Node Sends Its Own Impulses To The Bundle Of His

5. The AP Travels Down The Septum Via The L & R Bundle Branch

6. AP Goes To Apex (Bottom Of Heart) And Stimulates The Purkinje Fibers Which Causes The Ventricles To Contract

ECG Stands For Electrocardiogram (ECG or EKG)

A Record Of The Electrical Activity Of The Heart

Can Show The Heart’s:

• Speed

• Strength

• Rhythm

• Timing

• Base Of P - The SA Node Fires

• P- P-Wave - Atrial Contraction

• R- QRS Complex - Ventricles Receives AP And Contract - Atria Relaxes

• T- T-wave - Ventricles Relax, Heart “Resets” For Next impulse

Common Problems With Electrical System:

1. Arrythmia - Any Problem With Heart Rate Or Rhythm (AKA Normal Sinus Rhythm)

a. Tachycardia - Resting Heart Rate Over 100 bpm

b. Bradycardia - Resting Heart Rate <60 bpm

c. Fibrillations - Unsynchronized Contractions Of Either Atria Or Ventricles Leading To Dangerous Spasmodic Heart Activity

The Cardiac Cycle

The Cardiac Cycle - The Sequence Of Events In One Heatbeart.

Clinical Significance:

• Electrical Events

• Mechanical Events (Contractions / Valves)

• Sounds (Valves)

Phases - 1. Diastole

Diastole - Term To Describe A Relaxed Heart

• Atria & Ventricles Relaxed

• Blood Flows Into Heart Passively

Phases - 2. Atrial Systole

Atrial Systole - Atria Contraction

• Blood Pushed Into Ventricles

• AV Valves Are Open

• Semilunar Valves Closed

Phases - 3. Ventricular Systole

Ventricular Systole - Ventricle Contracting

1. Atria Relax

2. AV Valves Close (Heart Sounds 1 “LUB”) & SL Valves Open

3. Blood Pushed Out Of Ventricles Into Arteries

4. SL Valves Then Close (Heart Sounds 2 “DUB”)

Blood Pressure

Blood Pressure - The Amount Of Force The Blood Is Exerting Against Your Artery Walls When The Ventricles Contract

Normal: 120/80

a. Hypertension - Consistently High BP: 140/90 Or Higher

b. Hypotension - Consistently Low BP: Less Than 90/60

The Pressure Of Blood In The Vessels When The Heart Beats: Systolic Pressure: Top # In BP

The Pressure Between Beats When The Heart Relaxes: Diastolic Pressure: Bottom # In BP