Anatomy and Physiology Chapter 8: Heart and Blood Vessels

Arteries

Thick walled, transport blood away from the heart under high pressure

Capillaries

Exchange solutes and water with cells via interstitial fluid

• Most surface area of any blood vessels, spread out so velocity of flow decreases

Veins

Thin walled, return blood to heart

• More constricted a vein is, faster the flow

• Only veins have valves

Layers of vessel walls

• Endothelium: squamous epithelial cells, continuation of heart lining

• Smooth muscle with elastic connective tissue

• Collagen: anchors vessels to tissue

Aneurysm

Ballooning of artery wall

Arteriole

• Smallest arteries, connect to capillaries

• Lack of connective tissue and have a smaller smooth muscle layer

Precapillary sphincter

Smooth muscle that controls blood flow into capillaries

Vasolidation

Relaxation of vascular smooth muscle increases capillary flow

Vasoconstriction

Constriction of vascular smooth muscle, decreases flow into capillaries

Lymphatic system

• System consisting of the blood and blood vessels, but not RBCs or plasma proteins

• Picks up objects too large to diffuse in capillaries

  • Lymph is transported to veins near the heart, where it rejoins the blood

How does blood return to the heart?

• Squeezing of skeletal muscles

• Valves that permit only one-way blood flow

• Respiratory pump from breathing pressure

Pericardium

Protects and anchors heart

Pericardial cavity

• Film of fluid that reduces friction

Heart walls

• Epicardium: thin layer of epithelial and connective tissue

• Myocardium: thick layer of cardiac muscle, bulk of heart

  • Contracting part of heart

• Endocardium: thin, endothelial layer resting on connective tissue

  • continuous with the endothelium

Components of the heart

• Atria: top of heart

• Ventricles: bottom of hear

• Septum: separates left and right sides

Types of valves

• Atrioventricular valves: prevent backflow between chambers

• Semilunar valves: prevent backflow between ventricles and pulmonary arteries/veins

Heart circuits

• Pulmonary circuit: carries deoxygenated blood from the heart to lungs

• Systemic circuit: carries oxygenated blood to limbs

Coronary arteries

Leads to capillaries that supply blood to the heart

Cardiac cycle

1. Atrial systole: atria contract, filling ventricles

   1. AV open, SV close

2. Ventricular systole: ventricles contract, blood moves to the  pulmonary trunk and aorta

   1. AV close, atria relax and fill with blood

3. Diastole: aorta and ventricles relax

   1. AV and SV close

Cardiac conduction system

Cardiac cells that initiate/distribute electrical influences

• Begins in sinoatrial node (right atrium), initiates heartbeat

• The reaches the atrioventricular node, and then reaches the atrioventricular bundle that conducts impulses to the left and right ventricles

• Extend into smaller Purkinje fibers that carry the impulse into the myocardium of ventricles

Blood pressue

Force exerted by blood against blood vessel walls, 

• Generated by heart pumping

• Measured with a sphygomanometer, measures the efficiency of the cardiovascular system

• Healthy blood pressure is 120/80

Systolic pressure

Pressure in arterial vessels

• Happens during ventricular systole

Diastole pressure

Lowest pressure

• Happens in ventricular diastole

Hypertension

High bloop pressure, increased strain on cardiovascular system

• Isolated systolic hypertension: systolic pressure is high, diastolic pressure is normal

Hypotension

Low blood pressure, reduced oxygen to brain and other organs

• Below 90 in the top BP number, below 60 in the bottom

Baroreceptors

• Baroreceptors: regulate arterial blood pressure:

  • Increase in blood pressure stretches baroreceptors

  • Sensory neurons fire, sending signals to the cardiovascular center of the brain

  • Heart rate and force of contraction is lessened to reduce blood pressure 

Angina

Narrowing of coronary arteries, insufficient heart circulation

Heart attack

death of heart tissue caused by poor oxygen supply

Heart failure

inefficiency and weak pumping of blood

• Congestive: buildup of interstitial fluid

Embolism

Blockage of blood vessels

• Can be pulmonary, cerebral, or cardiac

Stroke

Interruption in blood supply to the brain

Normal resting HR

Between 60 and 100 BPM

• Below is bradycardia

• Higher is tachycardia

• Over 170 BPM is atrial fibrillation, risk of stroke

Cardiac output formula

Heart rate*stroke volume

Sympathetic nervous system effect on heart

High blood pressure and heart rate, uses epinephrine and norepinephrine

Parasympathetic nervous system effect on heart

Lower blood pressure and heart rate, uses acetylcholine

Label ECG 

• P wave: impulse across atria (Atrial contraction)

• QRS complex: spread of impulse, including all the way down to Purkinje fibers, depolarization during ventricular contraction

• 5: ventricular relaxation, repolarization

Label and function

Aorta, pumps blood to the rest of the body after leaving heart

• Area where blood flows the fastest

Label and function

Superior vena cava, brings in deoxygenated blood from above the heart

Label and function

Left pulmonary artery, sends deoxygenated blood to the left lung

Label and function

Right pulmonary artery, sends deoxygenated blood to the right lung

Label and function

Pulmonary trunk, branches into the pulmonary arteries

Label and function

Pulmonary veins, bring oxygenated blood back from the veins to the heart

Label and function

Left atrium, receives oxygenated blood and pumps it into the left atrium

Label and function

Aortic semilunar valve, prevents backflow from the aorta to the left ventricle

Label and function

Pulmonary semilunar valve, prevents backflow from the pulmonary artery into the left ventricle

Label and function

Inferior vena cava, brings in blood from below the heart

Label and function

Right atrioventricular valve, prevents blood from flowing back into the right atrium

Label and function

Left atrioventricular valve, prevents blood from flowing back into the left atrium

Label and function

Left ventricle, pumps oxygenated blood into the aorta

Label and function

Right atrium, pumps deoxygenated blood into the right ventricle

Label and function

Right ventricle, pumps blood into the pulmonary trunk

Label and function

• Chordae tendineae and papillary muscles, help maintain valve functions