Cardiovascular system

Anatomy & Physiology

Keith & His Gorgeous Cardiac Muscle

• http://www.bbc.co.uk/schools/gcsebitesize/pe/appliedanatomy/circulatory/0_anatomy_circulatorysys_act.shtml

Heart General Info• Approximately the size of one’s fist• Found in the mediastinum• Supply blood to the body• Important role in immune system

• http://www.phschool.com/science/biology_place/biocoach/cardio1/anatomy.html

ANATOMY OF THE CARDIOVASCULAR SYSTEM

Heart Anatomy• Covered with 2 linings-pericardium

– Parietal layer-outer layer– Visceral layer-aka epicardium, inner layer that

is attached to the myocardium• Linings filled with fluid to reduce the

friction from beating heart

• Heart wall– Myocardium-the

heart muscle itself– Endocardium-inside

the heart, lines the chambers

– Septum-the muscular wall dividing the heart into right and left halves

Heart Anatomy• 4 chambers

– 2 atria• Upper chambers• Receive blood• Right atria receives deoxygenated blood from the body• Left atria receives oxygenated blood from the lungs

– 2 ventricles• Lower chambers• Left wall is 3x as thick as the right• Pumps blood away from the heart• Right ventricle send deoxygenated blood to lungs• Left ventricle sends oxygenated blood to body

Accessory Structures

• Septum – the muscular wall dividing the heart into right and left halves

• Heart valves – prevents the backflow of blood

• Papillary muscles• Chordae tendineae

Great Vessels• Vena cava-largest vein(s)

– Superior-receives deoxygenated blood from upper body

– Inferior-receives deoxygenated blood from lower body• Pulmonary arteries-carry deoxygenated blood to

the lungs from the right ventricle• Pulmonary veins-carry oxygenated blood to the

left atrium of the heart from the lungs• Aorta –largest artery, carries oxygenated

blood to distribute to the rest of the body• http://www.phschool.com/science/biology_place/b

iocoach/cardio1/cycle.html

Cardiovascular Circuits• Pulmonary Circuit-transports blood from

the right side of the hear to the lungs, then back to the left side of the heart

• Systemic circuit-transports blood from the left side of the heart to all parts of the body and then back to the right side of the heart

• Coronary circuit-transports blood from the left side of the heart to the heart tissues and back to the right side of the heart

Valves

• Tough fibrous tissues between the heart chambers and major blood vessels of the heart

• Gate-like structures prevent the backflow of blood

Valves continued• Atrioventricular valves, or AV valves-

between the atria and vetricles. When the ventricles contract, blood is forced upward and the valves close– Tricuspid valve-between the right atrium

and the right ventricle– Bicuspid/mitral valve-between the left atrium

and the left ventricle

Valves continued• Semilunar valves-3 half-moon pockets that

catch blood and balloon out to close the opening– Pulmonic semilunar valve-between the right

ventricle & the pulmonary arteries– Aortic semilunar valve-between the left

ventricle and the aortic arch– http://www.phschool.com/science/biology_pla

ce/biocoach/cardio1/cycle.html

Cardiac Circulation• The blood supply to the heart• Aorta->coronary arteries->capillaries in the

myocardium->coronary veins->coronary sinus->right atrium

• Blood in the chambers nourishes the endocardium• The coronary circuit opens only during the

relaxation phase of the cardiac cycle• Occlusion of the coronary artery-a myocardial

infarction (heart attack) occurs if collateral circulation is inadequate

Anatomy • Blood

– Plasma– Erythrocytes

• Hemoglobin – iron containing pigment of the erythrocytes that carries the oxygen

• Reticulocyte-immature red blood cells• Macrophages

Anatomy • Blood continued

– Leukocytes – white blood cells• Neutrophils-an elevation of this type usually indicates infection• Basophils• Eosinophils • Lymphocytes• Monocytes

– Thrombocytes • Also known as platelets• Smallest formed elements of the blood

– https://www.khanacademy.org/science/health-and-medicine/lab-values/v/what-s-inside-of-blood

Anatomy • Blood continued

– Blood types – decided on the presence of the A and/or B antigens on red blood cells. In type O, both antigens are absent. A patient receiving blood incompatible with his or her own can experience serious and possibly fatal reactions.• A• AB• B• O

– Study chart on page 91

HEART PHYSIOLOGY

Nerve Supply to the Heart• Alters the rate & force of cardiac contraction• Vagus nerve (parasympathetic nervous system)-

slows the heart rate• Sympathetic nerves-increase the heart rate• Epinephrine/norepinephrine-increases heart rate• Sensory (afferent) nerves-detect atria being

stretched and lack of oxygen (changes the rate of contractions)

• Angina-chest pain due to a lack of oxygen in coronary circulation

Intrinsic Conduction System• Automaticity• Enables the heart to contract without motor nerve

impulses• Arrhythmia-irregular heartbeat• SA (sinoatrial) node-known as the pacemaker,

located where the superior & inferior vena cava enter the right atrium

• AV (atrioventricular) node-sends impulses to the ventricles

• Bundle of HIS/bundle branches-in the septum• Purkinje fibers-in the heart wall• http://www.phschool.com/science/biology_place/bioc

oach/cardio1/electrical.html

OVERVIEW OF BLOOD VESSELS

Arteries• ALWAYS carry blood away from the heart• Thicker than veins to withstand pressure

exerted during systole• All but the pulmonary arteries carry

oxygenated blood• Aorta – the largest artery; 1 inch in diameter• Arterioles-the smallest arteries• Coronary arteries-most important; supply

blood to the heart muscle itself

Veins • Carry blood toward the heart• All but the pulmonary veins carry

deoxygenated blood• Layers are much thinner, and less elastic• Have a series of internal valves that work

against gravity to prevent backflow• Superior and inferior vena cava-largest

veins• Venules-smallest veins

Capillaries • Tiny, microscopic vessels• Walls are one cell layer thick• Function-to transport and diffuse essential

material to and from the body’s cells and the blood

Trace a drop of blood• Start at the capillaries in your finger

PULSE

Pulse points• The pressure of blood pushing against the wall of

an artery and the heart beats-systole• Common pulse sites

– Temporal-side of the forehead– Carotid – neck– Brachial – the medial aspect of the forearm at the

antecubital space (crease of the elbow)– Radial – the lateral aspect of the wrist on the thumb

side– Femoral – the medial aspect of the upper thigh or groin– Dorsalis pedis – on the superior aspect of the foot arch

BLOOD PRESSURE

Blood Pressure• Systole – the maximum pressure

against the walls of the blood vessels formed during a ventricular contraction

• Diastole – the minimum pressure during ventricular relaxation

• Measure in mm of HG

Blood Pressure• Normal Ranges

– Systolic = 100-140– Diastolic = 60-90

• Hypotension – systolic < 90• Hypertension – systolic >150 and/or

diastolic >90