The Cardiovascular System

Chapter 15

Human Circulation

• Double loop circulation

• Pulmonary circuit

• Systemic circuit

15. 1 The Heart

Size and Location of the Human Heart

• Location: • Bordered

laterally by the lungs

• Posteriorly by the vertebrae

• Anteriorly by the sternum

Covering of the Heart• Pericardium • Fibrous pericardium –

surrounds a more delicate membrane• Visceral pericardium

(epicardium)• Parietal pericardium –

epicardium folds to line inside of fibrous pericardium

• Between the parietal and visceral layers is pericardial cavity• Contains serous fluid• Reduces friction

Wall of the Heart

• Epicardium

• Myocardium

• Endocardium

Epicardium

• Outermost layer of the heart

• Corresponds with visceral pericardium

• Contains • Capillaries and nerve

fibers• Fat tissue along

blood vessels

Myocardium

• Middle layer

• Cardiac muscle to pump blood

• Muscle tissue is arranged in layers, separated by vascular connective tissue

Endocardium

• Innermost layer

• Epithelium, connective tissue

• Blood vessels

• Purkinje fibers• Specialized cardiac muscle fibers – propagate

signal through heart

• Lines all heart chambers, valves and lining extends into blood vessels

Heart Chambers and Valves

• 4 chambers• 2 atria• 2 ventricles

Atrium (Atria)

• Upper chambers of the heart

• Receive blood

• Thin walled

Ventricles

• Lower chambers

• Very muscular

• Right and Left Ventricles separated by the interventricular septum

Valves of the Heart

• Right Atrioventricular Valve (tricuspid)

• Pulmonary Valve• Tricuspid valve

• NO chordae tendineae or papillary muscles

• Left Atrioventricular Valve (Mitral Valve)• Bicuspid valve

• Aortic Valve

Heart Chambers and Valves

• Right atrium• Receives blood from the superior vena cava,

inferior vena cava• Coronary sinus – from myocardium

Valves

• Chordae tendineae – attach to tricuspid on ventricular side• Originate from papillary

muscles

• Prevent tricuspid valve from flipping into the atrium

Right Ventricle

• Thinner walls than the left ventricle

• Pumps blood to the lungs

• Exits heart and into the pulmonary trunk• Divides into left and

right pulmonary arteries

Return to the heart…

• From lungs, blood exits through pulmonary veins (4)• Two from right lung, two from left lung

• Blood enters left atrium

Left Atrium

• Blood passes from left atrium to left ventricle through the mitral valve

Left Ventricle and Aorta

• Left ventricle contracts• Closing mitral valve• Sends blood to aorta through aortic valve

Blood Supply to the Heart

• Coronary arteries – from aorta• Right and left

• Cardiac veins – drain deoxygenated blood from heart• Join at the coronary sinus• Empties into right atrium

Label the Heart with Blood Flow

15.3 Heart Actions

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Heart Actions

• Systole• Contraction• Depends on which part of the heart• Atrial systole• Ventricular systole

• Diastole• Relaxation• Atrial diastole• Ventricular diastole

Cardiac Cycle

• Cycle of contractions between the atria and ventricles

Heart Sounds

• Lubb Dubb

• Lubb – ventricular systole• AV valves are closing

• Dubb – ventricular diastole• Pulmonary and aortic valves are closing

Heart Sounds

• Can tell you the condition of the heart valves

• Murmur: some blood leaks back through the valve• Many murmurs are harmless• Some can be a sign of serious valve damage

Electrocardiogram

Electrocardiogram

• ECG (EKG)

• Measures electrical changes within the myocardium during cardiac cycle

Steps of an ECG

• P wave

• QRS complex• Q wave• R wave• S wave

• T wave

P Wave

• Depolarization of atrial fibers

QRS Complex

• Indicates depolarization of ventricular fibers prior to contraction

T Wave

• Repolarization of ventricular fibers after contraction

ECG Uses

• Assess heart’s ability to conduct impulses

• PQ interval: time to travel from SA node through AV node

SA Node

• Coordinates events of the cardiac cycle

• Sinoatrial node

• Right atrium near opening to superior vena cava

• Pacemaker: generates heart’s rhythmic contractions

AV Node

• Atrioventricular node

• Coordinate contraction of ventricles together AND after the atria

• Impulse travels to AV bundle (bundle of His) and move through ventricular myocardium• Through right and left bundle branches

then to myocardium via Purkinje fibers

• Allow ventricle to contract as one unit

Nodes of the Heart

Regulation of Cardiac Cycle

• Vagus nerves: originate in the medulla oblongatta• Innervate and regulate heart

15.4 Blood Vessels

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Types of Blood Vessels

• Arteries

• Arterioles

• Capillaries

• Venules

• Veins

Blood Vessel Tunics

• 3 layers (tunics)• Tunica interna (innermost)• Epithelial cells

• Tunica media (middle)• Smooth muscle

• Tunica externa (outermost)• Tougher connective tissue, elastin, collagen

Arteries

• Muscular

• Very elastic

• Carry blood AWAY from the heart

• Smaller arteries = arterioles

Veins

• Little muscle

• Large lumen (space for blood to pass through), less muscle

• Brings blood to the heart

• Contain valves

• Flow through veins is assisted by skeletal muscle

• Small veins = venules

Arteries vs. Veins

Capillaries

• Smallest blood vessel

• Extension of innermost layer of arteries/veins – tunica interna

• Single layer of epithelial cells• Allow for easy exchange of materials from

blood to tissues

15.7 Arterial System

Leaving the heart…

Leaving the heart…

• Aorta• Largest artery

(diameter) in body

• Three major arteries come from the aortic arch• Brachiocephalic

artery

• Left common carotid artery

• Left subclavian artery

Brachiocephalic Artery

• Supply blood to the upper limb, head

• Divides to give rise to• Right common carotid

artery• Right subclavian

artery

Descending Aorta

• Extends from aortic arch down the body

• Thoracic aorta• Bronchial arteries• Esophageal arteries

More Descending Aorta

• Abdominal Aorta• Celiac artery• Left gastric (upper digestive tract)• Splenic (spleen …duh…)• Hepatic (liver)

• Phrenic artery (Diaphragm)• Superior mesenteric (Intestines (most))

Still the descending aorta…

• And MORE from the Abdominal Aorta• Suprarenal (adrenal glands)• Renal (kidneys)• Gonadal (gonads …duh…)• Inferior Mesenteric (parts of the colon,

rectum)• Lumbar (muscle of skin of posterior

abdominal wall)• Medial Sacral (sacrum, coccyx)

Arteries of the Brain, Neck, Head

• Vertebral• Through transverse processes

of cervical vertebrae• Enter skull through foramen

magnum

• External carotid

• Internal carotid

Arteries of the Shoulder and Upper Limb

• From subclavian artery

• Axillary artery (shoulder, upper chest)

• Brachial artery (along the humerus)

• Radial artery

• Ulnar artery

Arteries of the Lower Limb

• Abdominal aorta splits to form common iliac arteries

• Internal iliac artery (pelvic region)

• External iliac artery (main blood supply to lower limbs)• Inferior epigastric artery• Deep circumflex iliac artery

Arteries of the Lower Limb

• External iliac artery becomes the femoral artery (deep femoral, superficial femoral)

• Femoral artery becomes the popliteal artery as it passes over the patella• Divides • Anterior tibial artery• Posterior tibial artery

Venous System

How Veins Work

• Capillaries join to form venules

• Venules join to form small veins

• Small veins join to form large veins

Veins

• Veins typically are paired with an artery• Renal artery and the renal vein• Bring blood to the kidney from the heart, take

blood from the kidney to the heart

• BUT not always

• Venous blood flow is assisted by skeletal muscle contraction

Veins

• Superior Vena Cava

• Inferior Vena Cava

• Both lead to the right atrium from the body

Veins from the Brain, Head, Neck

• External jugular vein

• Internal jugular vein

• Brachiocephalic vein

• Right subclavian vein

• Right axillary vein

Veins from the Upper Limb and Shoulder

• Paired• Radial veins• Ulnar veins• Brachial

veins

Veins from the Abdominal Viscera

• Originate in the capillaries of the stomach, intestines, pancreas, spleen

• Merge at the hepatic portal vein to the liver• Superior mesenteric vein (small intestine,

portions of colon)• Inferior mesenteric vein (colon and rectum)• Gastric veins (stomach)• Splenic vein (spleen, pancreas)

Hepatic Portal System

What happens in the liver?

• Regulation of glucose within the body

• Phagocytosis of microorganisms

• Breakdown of toxins

• After the liver, blood enters the hepatic veins and the inferior vena cava

Veins from Lower Limb and Pelvis

• Anterior tibial vein

• Posterior tibial vein

• Popliteal vein

• Femoral vein

• Great saphenous vein (largest vein in the body – extends from medial foot to the femoral vein)

• External iliac vein

Cardiovascular Diseases and Abnormalities

1. Cardiac Arrest2. Stroke3. Aneurysm4. Arteriosclerosis /

Atherosclerosis5. Murmur6. Hypertension7. Myocardial Infarction

• What causes the disease/abnormality?

• What are some possible effects of the disease/abnormality?

• How is it diagnosed?

• Possible treatments?

Cardiac Arrest

• Cause: heart’s electrical system malfunctions, may be caused by abnormal or irregular heart rhythms

• Effects: often results in death, brain death occurs within a few minutes if situation isn’t reversed, sudden cardiac arrest: death within 1 hr. of symptoms

• Diagnosis: hard to detect because so sudden, but symptoms are- loss of consciousness, no breathing, no pulse, chest pain, weakness, pounding in chest, feeling faint

• Treatments: CPR right away, defibulator

StrokeCauses: Occurs when blood flow to the brain is interrupted or reduced

• Arteries to brain become narrowed or blocked• Blood vessels in the brain leakEffects: • Brain damage• Impairment – loss of normal function of part of the body (may be

permanent) • DeathDiagnosis:• Blood tests• Physical examination• (CT) scan• MRI• Cerebral angiogramTreatments:• Aspirin• Mechanical clot removal• Angioplasty and stents• Blood vessel repair• Stoke recovery and rehabilitation

Aneurysm

• Part of the artery/cardiac chamber swells with blood forming a bubble

• Most commonly found on the wall of the (left) aorta

• Causes: atherosclerosis, smoking, hypertension, vaculities, cocaine usage, and/or genetic links

• Effects: hemorrhage, other complications, or sudden death

• Diagnosis: abdominal ultrasound, CT, MRI, regular screening

• Treatment: wait and watch or surgery• All depends on the size of the aneurysm

Arteriosclerosis / Atherosclerosis

• Arteriosclerosis- it is caused by the thickening and hardening of the arteries

• Atherosclerosis- this is caused by the build up of fatty plaques in the arteries

• Effects- blood flow will decrease and pressure will increase

• Diagnosis- your doctor may find signs of narrowed, enlarged or hardened arteries during a physical exam.• A weak or absent pulse below the narrowed area of your artery• Decreased blood pressure in an affected limb• Whooshing sounds (bruits) over your arteries, heard using a stethoscope• Signs of pulsating bulge (aneurysm) in your abdomen or behind your knee• Evidence of poor wound healing in the area where your blood flow is restricted

Treatments- cholesterol medications, anti-platelet medication, beta blocker medications, calcium channel blockers, water pills, bypass surgery, thrombolytic therapy

Murmur

• Causes-

• Valve abnormalities:

• Stenosis- narrowing of the heart valve.

• Regurgitations- leaks blood backwards.

• Sclerosis- mild narrowing.

• Prolapse- Bowing of the heart valve.

• Endocarditis- Infection of the heart.

• Effects: Chest pain, shortness of breath, swelling of extremities.

• Diagnosis: Patient history, physical examination.

• Treatment: Monitored, antibiotics or surgery.

murmur

Hypertension

• High Blood Pressure (HBP)

• Causes: Smoking, being overweight, lack of physical activity, too much salt in diet, high alcohol consumption, stress, old age, genetics, chronic kidney disease, adrenal and thyroid disorders.

• Effects: nervousness, sweating, difficulty sleeping, facial flushing, blood spots in the eyes, dizziness, stroke, death

• Diagnosis: blood pressure test (optimal blood pressure is less than 120/80 mmHG)

• Treatments: lifestyle changes (diet, exercise, stop smoking, managing stress, limit alcohol consumption) and medication.

Myocardial Infarction

• Heart Attack

• Occurs when an artery leading to the heart is completely blocked off and the heart doesn’t get enough blood or oxygen, causing cells in that area to die( called an infarct)

• Feeling of DOOM, squeezing pain, heaviness, tightness, pressure in center of chest, shortness of breath, death

• ECG, blood tests, chest x-ray, stress test

• Change lifestyle, medications, surgical treatments, nutrition and dietary supplements, diets for people with high blood pressure.