Unit 2 Comprehensive Study Guide: Cardiovascular System Anatomy and Physiology

Absolutely — I made these notes directly from your Unit 2 Learning Objectives so they focus on what you’re expected to know for Chapters 19 and 20.

Unit 2 Study Notes

Chapter 19 — The Heart

1. Heart structures and their functions

Heart wall/layers

Epicardium

  • Outermost layer of the heart wall

  • Also called the visceral pericardium

  • Protects the heart and reduces friction

Myocardium

  • Thick muscular middle layer

  • Made of cardiac muscle

  • Responsible for heart contractions

Endocardium

  • Smooth inner lining of the heart chambers and valves

  • Helps blood flow smoothly through the heart

Major blood vessels

Superior vena cava

  • Returns deoxygenated blood from the upper body to the right atrium

Inferior vena cava

  • Returns deoxygenated blood from the lower body to the right atrium

Pulmonary trunk

  • Carries deoxygenated blood out of the right ventricle

  • Divides into pulmonary arteries

Pulmonary arteries

  • Carry deoxygenated blood from the heart to the lungs

Pulmonary veins

  • Carry oxygenated blood from the lungs to the left atrium

Aorta

  • Largest artery in the body

  • Carries oxygenated blood from the left ventricle to systemic circulation

Heart chambers

Right atrium

  • Receives deoxygenated blood from:

    • Superior vena cava

    • Inferior vena cava

    • Coronary sinus

Right ventricle

  • Pumps deoxygenated blood into the pulmonary trunk

  • Sends blood to the lungs

Left atrium

  • Receives oxygenated blood from pulmonary veins

Left ventricle

  • Pumps oxygenated blood into the aorta

  • Has the thickest myocardium because it pumps blood throughout the body

Heart valves

Tricuspid valve

  • Between right atrium and right ventricle

Pulmonary semilunar valve

  • Between right ventricle and pulmonary trunk

Bicuspid/mitral valve

  • Between left atrium and left ventricle

Aortic semilunar valve

  • Between left ventricle and aorta

Main purpose of valves

Prevent backflow of blood

Chordae tendineae

  • Fibrous cords attached to AV valves

  • Attach valves to papillary muscles

  • Prevent valves from flipping backward during ventricular contraction

Papillary muscles

  • Contract during ventricular systole

  • Tighten chordae tendineae

  • Help prevent AV valve prolapse

Septum

  • Wall separating the right and left sides of the heart

  • Prevents oxygenated and deoxygenated blood from mixing

Apex

  • Pointed inferior tip of the heart

  • Mainly formed by the left ventricle

Coronary circulation

Coronary arteries

  • Supply oxygen-rich blood to the myocardium

Cardiac veins

  • Drain deoxygenated blood from heart muscle

Coronary sinus

  • Collects blood from cardiac veins

  • Empties into right atrium

2. Blood flow through the heart

You should know this in order:

Body
↓
Superior/inferior vena cava
↓
Right atrium
↓
Tricuspid valve
↓
Right ventricle
↓
Pulmonary semilunar valve
↓
Pulmonary trunk
↓
Pulmonary arteries
↓
Lungs
↓
Pulmonary veins
↓
Left atrium
↓
Bicuspid/mitral valve
↓
Left ventricle
↓
Aortic semilunar valve
↓
Aorta
↓
Body

Easy way to divide it

Right side = CO₂-rich/deoxygenated blood

Left side = O₂-rich/oxygenated blood

3. Congenital heart defects

Septal defect

  • Abnormal opening in the septum

  • Allows blood to move between right and left sides of heart

  • Can cause oxygenated and deoxygenated blood to mix

Patent ductus arteriosus

Normally, the ductus arteriosus closes after birth.

If it stays open:

  • Blood can flow abnormally between the aorta and pulmonary artery

  • May increase blood flow to lungs

Tetralogy of Fallot

A congenital defect involving four abnormalities.

Know that it causes:

  • Reduced oxygenation

  • Cyanosis may occur

The four problems classically include:

  1. Ventricular septal defect

  2. Pulmonary stenosis

  3. Overriding aorta

  4. Right ventricular hypertrophy

4. Heart conduction system

Know the order:

1. SA node

Sinoatrial node

  • Natural pacemaker

  • Starts each heartbeat

  • Causes atrial depolarization/contraction

↓

2. AV node

Atrioventricular node

  • Briefly delays impulse

  • Gives ventricles time to fill

↓

3. AV bundle / Bundle of His

↓

4. Right and left bundle branches

↓

5. Purkinje fibers

  • Spread impulse through ventricular myocardium

  • Cause ventricular contraction

Memorize:

SA → AV → Bundle of His → bundle branches → Purkinje

5. ECG/EKG

You need to recognize a normal Lead II ECG.

P wave

Represents:
Atrial depolarization

Followed by atrial contraction.

Change may occur with:

  • Atrial enlargement

  • Atrial rhythm abnormalities

QRS complex

Represents:
Ventricular depolarization

Followed by ventricular contraction.

Atrial repolarization occurs at the same time but is hidden.

T wave

Represents:
Ventricular repolarization

Memorize:

P = atria depolarize

QRS = ventricles depolarize

T = ventricles repolarize

6. Cardiac cycle

Systole

Means:
Contraction

Ventricular systole

  • Ventricles contract

  • AV valves close

  • Semilunar valves open

  • Blood is ejected

Diastole

Means:
Relaxation

Ventricular diastole

  • Ventricles relax

  • Semilunar valves close

  • AV valves open

  • Ventricles fill

Heart sounds

S1 — “Lub”

Caused mainly by:
Closure of AV valves

  • Tricuspid

  • Mitral

Occurs at beginning of ventricular systole.

S2 — “Dub”

Caused by:
Closure of semilunar valves

  • Pulmonary

  • Aortic

Occurs at beginning of ventricular diastole.

7. Bradycardia, tachycardia, angina

Bradycardia

Heart rate below normal.

Usually:
<60 beats/min in adults

Tachycardia

Heart rate above normal.

Usually:
>100 beats/min in adults

Angina pectoris

Chest pain caused by:
Temporary inadequate blood flow/oxygen to the heart muscle

Often related to coronary artery narrowing.

Usually does not mean permanent myocardial death has occurred.

8. Major cardiovascular diseases

Coronary thrombosis

A blood clot forms in a coronary artery.

Effect:

  • Reduces or blocks blood flow to myocardium

  • Can cause myocardial infarction

Myocardial infarction

Also called:
Heart attack

Occurs when:

  • Blood flow to part of myocardium is blocked long enough for heart muscle cells to die

Common cause:

  • Coronary artery atherosclerosis with thrombosis

Possible symptoms:

  • Chest pressure/pain

  • Pain radiating to arm/jaw

  • Shortness of breath

  • Nausea

  • Sweating

Congestive heart failure

Occurs when:
Heart cannot pump enough blood to meet the body's needs

Left-sided failure

Often causes:

  • Pulmonary congestion

  • Shortness of breath

  • Fluid in lungs

Right-sided failure

Often causes:

  • Peripheral edema

  • Swelling

  • Venous congestion

Risk factors for cardiovascular disease

Know:

  • Smoking

  • Hypertension

  • High cholesterol

  • Diabetes

  • Obesity

  • Physical inactivity

  • Poor diet

  • Family history

  • Increasing age

Prevention includes:

  • Exercise

  • Healthy diet

  • Blood pressure control

  • Cholesterol control

  • Diabetes control

  • Avoid smoking

9. Normal cardiovascular values

Your objective specifically expects you to recognize normal and abnormal values and understand their relationship.

Blood pressure

Typical normal:
About 120/80 mmHg

Systolic pressure

  • Top number

  • Pressure during ventricular contraction

Diastolic pressure

  • Bottom number

  • Pressure during ventricular relaxation

Heart rate

Normal adult resting:
60–100 beats/min

Blood volume

Average adult:
About 5 liters

Varies with body size and sex.

Stroke volume

Amount of blood pumped by one ventricle per heartbeat.

Typical resting value:
About 70 mL/beat

Formula

SV = EDV − ESV

End-diastolic volume — EDV

Amount of blood in a ventricle:
At the end of filling, before contraction

Greater EDV generally means greater preload.

End-systolic volume — ESV

Amount of blood remaining in a ventricle:
After contraction

Cardiac output

Amount of blood pumped by one ventricle per minute.

Formula

CO = HR × SV

Example:

70 beats/min × 70 mL/beat

≈ 4.9 L/min

Preload

Degree of ventricular stretching before contraction.

Usually related to:

  • Venous return

  • EDV

More blood filling the heart → more preload

Afterload

Resistance the ventricle has to overcome to eject blood.

Example:

  • High blood pressure increases afterload.

Contractility

Strength of cardiac muscle contraction.

Increased contractility:

  • Increases stroke volume

  • Decreases ESV

10. Frank-Starling Law

The more the heart fills, the more strongly it contracts—within normal physiological limits.

More venous return
→ higher EDV
→ greater stretch
→ stronger contraction
→ increased stroke volume

Remember:

More in → more out

Chapter 20 — Blood Vessels & Circulation

The Chapter 20 objectives require you to compare vessel types, understand circulation routes, blood pressure regulation, edema, and vascular diseases.

1. Types of blood vessels

Arteries

Carry blood:
Away from the heart

Characteristics:

  • Thick walls

  • High pressure

  • Large amount of smooth muscle and elastic tissue

Arterioles

Small arteries.

Main function:
Control blood flow into capillaries and regulate peripheral resistance

Can:

  • Vasoconstrict

  • Vasodilate

Very important for blood pressure.

Capillaries

Smallest blood vessels.

Wall:
One endothelial cell thick

Function:

  • Exchange gases

  • Nutrients

  • Wastes

  • Fluids

between blood and tissues.

Venules

Small vessels that collect blood from capillaries.

Eventually merge into veins.

Veins

Carry blood:
Toward the heart

Characteristics:

  • Lower pressure

  • Thinner walls than arteries

  • Larger lumen

  • Many contain valves

Veins act as:
Blood reservoirs/capacitance vessels

Layers of blood vessel walls

Know these three:

Tunica interna/intima

  • Innermost

  • Endothelium

Tunica media

  • Smooth muscle

  • Elastic tissue

  • Responsible for vasoconstriction and vasodilation

Tunica externa

  • Outer connective tissue

  • Supports/protects vessel

2. Venous pump and varicose veins

Blood in veins is under low pressure.

Skeletal muscle pump

When skeletal muscles contract:

  • They squeeze veins.

  • Vein valves prevent backward flow.

  • Blood moves toward heart.

Respiratory pump

Breathing changes pressure in chest and abdomen.

Helps draw venous blood toward heart.

Varicose veins

Develop when:

  • Venous valves become weak or incompetent.

  • Blood pools in veins.

  • Veins become enlarged/twisted.

Common in:

  • Legs

3. Major arteries

You should be able to recognize these on diagrams.

Major vessels to know:

  • Aorta

  • Aortic arch

  • Brachiocephalic artery

  • Subclavian artery

  • Common carotid artery

  • Axillary artery

  • Brachial artery

  • Radial artery

  • Ulnar artery

  • Celiac artery

  • Superior mesenteric artery

  • Renal artery

  • Inferior mesenteric artery

  • Common iliac artery

  • Internal iliac artery

  • External iliac artery

  • Femoral artery

  • Popliteal artery

  • Anterior tibial artery

  • Posterior tibial artery

  • Pulmonary artery

  • Coronary arteries

Major veins to know

  • Ulnar

  • Radial

  • Median cubital

  • Basilic

  • Cephalic

  • Brachial

  • Axillary

  • Subclavian

  • External jugular

  • Internal jugular

  • Brachiocephalic

  • Superior vena cava

  • Inferior vena cava

  • Dorsal venous arch

  • Anterior tibial

  • Posterior tibial

  • Popliteal

  • Femoral

  • Great saphenous

  • External iliac

  • Internal iliac

  • Common iliac

  • Renal

  • Cardiac veins

High-yield arm sequence

Hand/forearm
→ radial + ulnar
→ brachial
→ axillary
→ subclavian

High-yield leg sequence

Anterior/posterior tibial
→ popliteal
→ femoral
→ external iliac
→ common iliac
→ inferior vena cava

4. Circulatory routes

Pulmonary circulation

Right ventricle
→ pulmonary trunk
→ pulmonary arteries
→ lungs
→ pulmonary veins
→ left atrium

Purpose:
Gas exchange

Coronary circulation

Aorta
→ coronary arteries
→ heart capillaries
→ cardiac veins
→ coronary sinus
→ right atrium

Purpose:
Supplies myocardium

Hepatic portal circulation

Blood from digestive organs travels to the liver before returning to the heart.

Basic path:

Digestive organs
→ hepatic portal vein
→ liver
→ hepatic veins
→ inferior vena cava

Purpose:

  • Liver processes absorbed nutrients

  • Detoxifies substances

Collateral circulation

Blood can reach tissue through:
Alternative pathways

Anastomosis

Connection between two blood vessels.

Purpose:

  • Provides another route if one vessel becomes blocked.

5. Edema

Edema means:
Excess fluid accumulation in tissues

Possible causes:

  • Increased capillary pressure

  • Decreased plasma protein levels

  • Increased capillary permeability

  • Lymphatic obstruction

  • Sodium/water retention

6. Factors affecting arterial blood pressure

A major relationship to know:

Blood pressure ≈ cardiac output × peripheral resistance

Cardiac output

If CO increases:
Blood pressure tends to increase

Remember:
CO = HR × SV

Heart rate

Higher HR can increase cardiac output and BP.

Vessel radius

Vasoconstriction

Vessel gets narrower:

  • Resistance increases

  • BP increases

Vasodilation

Vessel gets wider:

  • Resistance decreases

  • BP decreases

This is one of the most important factors affecting resistance.

Peripheral resistance

Resistance blood encounters as it moves through vessels.

Higher resistance:
Higher BP

Blood viscosity

Thicker blood:

  • Increases resistance

  • Increases BP

Example:
Polycythemia can increase viscosity.

Blood volume

More blood volume:

  • More venous return

  • Higher CO

  • Higher BP

Less volume:

  • Lower BP

Elasticity of arterial walls

Healthy elastic arteries:

  • Stretch when heart ejects blood

  • Recoil afterward

Loss of elasticity can contribute to hypertension.

Epinephrine

Generally:

  • Increases heart rate

  • Increases contractility

  • Can cause vasoconstriction in some vessels

  • Raises cardiac output/BP

ADH — vasopressin

Raises BP by:

  • Increasing water retention

  • Increasing blood volume

  • Causing vasoconstriction at higher concentrations

7. Homeostatic blood pressure regulation

You need to understand the roles of pressure receptors, chemoreceptors, and the medulla oblongata.

Baroreceptors

Pressure/stretch receptors.

Major locations:

  • Carotid sinus

  • Aortic arch

Detect changes in BP.

If BP increases

Baroreceptors fire more
→ brain reduces sympathetic activity
→ HR decreases
→ vessels dilate
→ BP decreases

If BP decreases

Baroreceptor firing decreases
→ sympathetic activity increases
→ HR increases
→ contractility increases
→ vasoconstriction
→ BP rises

Chemoreceptors

Monitor:

  • O₂

  • CO₂

  • pH

When oxygen decreases or CO₂ rises:

  • Cardiovascular center responds

  • Can increase sympathetic stimulation and blood pressure

Medulla oblongata

Contains cardiovascular/vasomotor centers.

Controls:

  • Heart rate

  • Contractility

  • Vessel diameter

8. Vascular conditions

Aneurysm

Abnormal weakening and bulging of a vessel wall.

Danger:

  • Can rupture

  • Severe internal bleeding may result

Common risk factors:

  • Hypertension

  • Atherosclerosis

  • Vessel weakness

Arteriosclerosis

General term meaning:
Hardening/thickening of arteries

Causes loss of elasticity.

Atherosclerosis

Type of arteriosclerosis involving:
Fatty plaques in arterial walls

Can:

  • Narrow arteries

  • Reduce blood flow

  • Promote clot formation

Risk factors:

  • High LDL

  • Smoking

  • Hypertension

  • Diabetes

  • Obesity

Hypertension

Persistently elevated blood pressure.

Can damage:

  • Heart

  • Blood vessels

  • Kidneys

  • Brain

  • Eyes

Often called a silent disease because symptoms may be absent.

Hypotension

Abnormally low blood pressure.

Can reduce perfusion to organs.

Symptoms may include:

  • Dizziness

  • Fainting

  • Weakness

Shock

A condition in which:
Tissues do not receive adequate blood flow and oxygen

Can result from:

  • Severe blood loss

  • Heart failure

  • Severe infection

  • Severe allergic reaction

  • Other causes

Effects:

  • Low BP

  • Rapid HR

  • Poor tissue perfusion

  • Organ dysfunction