CARDIOVASCULAR SYSTEM

1.Introduction

1.1.Part of the circulatory system along w/ lymphatic system

2.2.Composed of the heart and blood vessels

3.3.Functions: move blood to

  1. 1.deliver nutrients and oxygen
  2. 2.remove waste

2.THE HEART

1.General

  1. 1.Apex--inferior pointed end, Base--superior flattened end,
  2. 2.located in thoracic cavity between lungs, size of clenched fist

4.2.Coverings

  1. 1.parietal pericardium (pericardial sac)--composed DCT and SS epithelium, protects and anchors heart
  2. 2.visceral pericardium (epicardium)--continuation of SS epithelium that attaches to heart
  3. 3.pericardial cavity--forms between two layers, contains fluid that lubricates heart

5.3.Heart Wall

  1. 1.epicardium --protects heart, contains fatty deposits
  2. 2.myocardium --cardiac muscle tissue interwoven w/ CT, propels blood
  3. 3.endocardium --smooth, white membrane that lines internal surfaces of heart and blood vessels

6.4.Heart Chambers

  1. 1.atria --receive blood, pump it to next chamber
  2. 1.pectinate muscles --ridges of muscle in atria
  3. 2.internal septum --separates atria, contains fossa ovalis
  4. 3.vena cava and pulmonary veins
  5. 2.ventricles --provide force to push blood out of heart, myocardium is much thicker than atria's
  6. 1.trabeculae carnae --muscle ridges lining surface

  1. 2.papillary muscles
  2. 3.interventricular septum --separates ventricles
  3. 4.pulmonary trunk and aorta

7.5.Heart Valves

  1. 1.Atrioventricular valves --between atria and ventricles
  2. 1.tricuspid valve --between rt. atrium and rt. ventricle, formed by three cusps that point downward into ventricle
  3. 2.bicuspid or mitral valve --between lt. atrium and lt. ventricle, formed by two cusps
  4. 3.chordae tendinea --strands of CT that connect cusps to papillary muscles, anchor valves and prevent them from everting as blood pushes against them
  5. 2.Semilunar valves
  6. 1.pulmonary valve --DCT. between rt. ventricle and pulmonary trunk, composed of three halfmoon cusps that resemble bowls
  7. 2.aortic valve --between lt. ventricle and aorta

8.6.Blood Flow Through the Heart

9.7.Blood Supply to the Heart

10.8.Heart Physiology

  1. 1.cardiac cycle --contraction of both atria followed by contraction of both ventricles is one cycle
  2. 1.systole --state of contraction
  3. 2.diastole --state of relaxation
  4. 2.heart sounds --"lub-dup" sounds produced by blood turbulence as valves open and close, lub indicates closing AV valve, dup indicates closing SL valve, helpful in diagnosing heart problems

  1. 3.heart conduction system
  2. 1.cardiac muscle tissue have inherent ability to contract w/o nervous input
  3. 2.sinoatrial (SA) node --mass of cells in wall of rt. atrium, act as pacemaker as it initiates each cardiac cycle by sending out electrical signal causing atria to contract and stimulating AV node
  4. 3.atrioventricular (AV) node --second mass of cells near bottom of interatrial septum, sends signal down AV bundle that extends down interventricular septum to Purkinje fibers causing ventricles to contract
  5. 4.delay in signal as it travels down AV bundles allows time for atria to relax and collect blood, cycle starts aver again, 100,000 times each day
  6. 4.electrocardiogram (ECG of EKG)
  7. 1.measures electrical activity of heart as currents flow though body and records it in relation to time
  8. 2.Normal wave pattern: P, QRS, and T waves

(1)(1)P wave - SA node fires and depolarizes atria

(2)(2)QRS complex - ventricular depolarization, large due to muscle mass

(3)(3)T wave - repolarization of ventricles

  1. 3.useful tool for detecting heart problems
  1. 5.cardiac output
  2. 1.measurable value representing heart activity
  3. 2.heart rate - duration of each cardiac cycle, how fast
  4. 3.stroke volume -volume ejected by ventricles
  5. 4.cardiac output = H.R. x S.V. (normal 75 bpm x 70 ml)
  6. 5.Starling's law of the heart -strength of ventricular contraction is determined by stretch of muscles when filling w/ blood, more stretch = more strength
  7. 6.regulation of heart activity
  8. 1.autonomic control via medulla oblongata reflex center

(1)(1)parasympathetic -slow heart by releasing ACh

(2)(2)sympathetic - increase heart rate by releasing norepinephrine

  1. 2.baroreceptors -detect changes in blood pressure, located in aorta and carotid artery
  1. 3.BLOOD VESSELS

1.1.Arteries and Arterioles

  1. 1.arteries carry blood away from heart, branch into arterioles
  2. 2.structure
  3. 1.lumen - hollow interior
  4. 2.tunica intima - innermost layer, endothelium and CT
  5. 3.tunica media - smooth muscle and elastic fibers
  6. 4.tunica adventitia - thin layer of CT to anchor to surroundings
  7. 3.properties
  8. 1.contractibility and elasticity provided by t. media
  9. 2.stimulus from sympathetic nervous system, regulates blood pressure (vasoconstriction and dilation)

2.2.Capillaries

  1. 1.smallest blood vessels, less than .01 mm diameter, 1 RBC at a time
  2. 2.wall of endothelium allows for diffusion of oxygen and nutrients into cells and removal of wastes, leaky in places
  3. 3.connect arterioles w/ venules via capillary beds which may contain between 10 - 100 capillaries
  4. 4.precapillary sphincter - band of smooth muscle that controls blood flow into cap. bed

3.3.Venules and veins

  1. 1.carry blood towards the heart, usually deoxygenated
  2. 2.composed of same three layers as arteries, only thinner w/ less elasticity, larger lumen
  3. 3.65% of blood contained in veins, under low pressure

  1. 4.contain one way valves made of t. intima

4.4.Blood Pressure

  1. 1.contraction of ventricles causes blood to exert force on walls of vessels
  2. 2.arterial BP - highest in aorta
  3. 1.systolic pressure - peak pressure at ventricular contraction, 120 mm Hg normal
  4. 2.diastolic pressure - lowest pressure at ventricular relaxation, 70 - 80 mm Hg normal
  5. 3.sphygmonmanometer - blood pressure cuff
  6. 3.factors affecting BP
  7. 1.cardiac output = heart rate x stroke volume
  8. 2.peripheral resistance

(1)(1)diameter of blood vessels (clogged arteries?)

(2)(2)viscosity of blood ( 30W or 60Woil?)

  1. 3.blood volume

(1)(1)plasma volume - normal 5 liters

(2)(2)hematocrit - blood cells

  1. 4.regulation of BP
  2. 1.nervous - autonomic fibers control HR, tunica media of arterioles, stimulated by baroreceptors and chemoreceptors in major vessels
  3. 2.hormonal - epinephrine and nor epinephrine8 cardiac output, 8per. resistance; ADH 8 water retention in kidneys
  4. 3.kidney control - main long term control for BP; control water retention, angiotensin produces vasoconstriction, aldosterone causes reabsorption of Na+