The Cardiovascular System

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The Cardiovascular System

• Chapter 13

Human Heart
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13.1 Introduction

• The heart pump 7,000 liters of blood/day.
• Pumps 2.5 billion times in an average life span.
• The heart, arteries, veins, capillaries, and
  blood make up the cardiovascular system.
• The main job of the cardiovascular system is to
  deliver oxygen and nutrients to all body cells
  and remove waste from all cells.
• Without fresh O2 and removing waste death would
  be quick.

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13.2 Structure of the Heart

• The heart is a hollow, cone-shaped, muscular pump
  located within the thoracic cavity and resting on
  the diaphragm. The upper most of the heart is the
  BASE. The pointy end is the Apex.
• An average heart is about the size of your fist.
• The base of the heart lies beneath your 2nd rib.
• Pericardium is the covering of the heart.
• Pericardial cavity contains a small volume of
  fluid that reduces friction the pericardium and
  the heart itself.

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13.2 Continued

• The wall of the heart is made of 3 layers
• The outer pericardium which protects the heart by
  reducing friction.
• The thickest middle myocardium consist mostly of
  muscle and pumps blood out of the heart.
• The inner endocardium consists of epithelium and
  connective tissue that contains many elastic and
  collagenous fibers. The endocardium is continuous
  with the inner linings of blood vessels attached
  to the heart.

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13.2 Heart Chambers and Valves

• The heart is divided into 4 chambers.
• The upper chambers are the atria. Atria have thin
  walls and receive blood returning to the heart.
• The lower chambers are the ventricles. Ventricles
  receive blood from the atria and contract to
  force blood out of the heart into arteries.

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Bicuspid valve
Tricuspid
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• The septum separates the atrium and ventricle on
  the right side from the left side. The blood from
  the two sides NEVER mixes.
• An atrioventricular valve, the tricuspid on the
  RIGHT side and the bicuspid (Mitral) on the LEFT
  side ensure one-way blood flow from atria to
  ventricle.
• Tricuspid has 3 cusps allows blood to move from
  the right atrium into the right ventricle.

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• Veins carry blood to the heart.
• Arteries carry blood away from the heart. A-away.
• The right atrium receives blood from two large
  veins and 1 small.
• Superior vena cava
• Inferior vena cava
• (Small) Coronary sinus drains blood into the
  right atrium from the myocardium.

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• Strong, fibrous strings called chordae tendineae
  attach to the cusps of the tricuspid valve on the
  ventricular side. They keep the cusps from
  swinging back into the atrium.
• The right ventricle has a thinner muscular wall
  than the left ventricle.
• The right chamber pumps blood a short distance to
  the lungs.
• The left ventricle pumps blood to all other
  parts of the body.

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Valves

• The bicuspid and tricuspid valves are called
  atrioventricular valves because they are between
  atria and ventricles.
• The pulmonary and aortic valves are called
  semilunar because of the half-moon shapes of
  their cusps.

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Skeleton of the Heart

• Rings of dense connective tissue surround the
  pulmonary trunk and aorta and dense masses of
  connective tissue make up the Skeleton of the
  Heart.
• These rings provide firm attachments for heart
  valves and for muscle fibers.
• They prevent the outlets of the atria and
  ventricles from dilating during contraction.

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Path of Blood

• Vena cava (Largest vein in the body)
• Right atrium (Right side deoxygenated blood)
• Tricuspid value
• Right ventricle
• Pulmonary artery
• Right and left lung (Picks up O2 drops off CO2)
• Pulmonary vein
• Left atrium (Left side oxygenated blood)
• Bicuspid value
• Left ventricle
• Aorta (Largest artery in the body)
• To all body cells

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Blood Supply to the Heart

• Coronary vessels carry blood to and from the
  heart itself.
• Heart attack is the death of a section of heart
  muscle.

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Heart Actions

• Systole atria contract and ventricles relaxed.
• Diastole atria relaxed and ventricles contract.
• Both atria contract while both ventricles relax
  and them both ventricles contract as both atria
  relax.

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Heart Sounds

• A heartbeat heard through a stethoscope sounds
  like lubb-dupp.
• The sound is caused by the closing of valves.
• Lubb when bicuspid and tricuspid valves close.
• Dupp when semilunar valves close.
• A heart murmur blood flowing backward through the
  heart when valves are not closing tightly.
• Lubb-dupp-swish would signal a problem with the
  semilunar valve.
• Lubb-swish-dupp problem with bicuspid and/or
  tricuspid valve.

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Cardiac Muscle Fibers

• Cardiac muscle fibers function much like those of
  skeletal muscles. The heart pumps as one unit.
• Functional syncytium is a mass of merged cells
  that function as a unit.

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• Sinoatrial node (S-A node) is a small, elongated
  mass of specialized cardiac muscle tissue just
  beneath the epicardium in the right atrium.
• S-A node are the cells that initiate the stimulus
  for contraction of the heart muscle.

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• Electrocardiogram (ECG)is the recording of the
  electrical charges that occur in the myocardium
  during a cardiac cycle.
• Blood volume of changes to accommodate cellular
  requirements. Example during strenous exercise,
  skeletal muscles require more blood.
• The cardiac control center is in the brains
  medulla oblongata.

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• The ions that influence the heart the most are
  potassium (K) and Calcium (Ca2).
• Excess potassium ions (hyperkalemia) decrease the
  rate and force of contractions.
• Low potassium ions (hypokalemia) the heart may
  develop a potentially life-threatening abnormal
  rhythm (arrhythmia).
• Excess calcium ions (hypercalcemia) increase
  heart actions, posing the danger that the heart
  will contract for a prolonged time.
• Low calcium ions (hypocalcemia) depresses heart
  action.

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13.4 Blood Vessels

• Arteries
• They carry blood away from the heart
• They carry blood under high pressure
• They are round in shape
• They have thick, muscular walls
• Arterioles are arteries that have divide and
  divide into progressively thinner tubes.
• Vasoconstriction when arteries contract.
• Vasodilation when arteries dilate.

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Veins

• Veins
• They carry blood to the heart
• They carry blood under low pressure
• They are flat in shape and have little muscle
• They have many one-way valves to keep blood
  flowing in one direction.

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96 000 kilometers of blood vessels in the human
body. 2 ½ times around the earth.
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13.5 Blood Pressure

• Blood pressure is the force of blood exerts
  against the inner walls of blood vessels.
• Blood pressure is most commonly refers to
  pressure in arteries.
• Pulse is the force of blood through an artery.

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• Blood pressure is recorded as a fraction.
  Systolic over diastolic.
• Systolic pressure is the maximum pressure during
  ventricular contraction.
• Diastolic pressure is the lowest pressure that
  remains in the arteries before the next
  contraction (ventricular relaxation).

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Heart Action

• Stroke Volume the volume of blood discharged from
  the left ventricle with each contraction.
• Cardiac output the volume discharged from the
  left ventricle per minute. Can be calculated by
  multiplying the stroke volume by the beats per
  minute.
• Blood volume equals the sum of the formed
  elements and plasma volumes in the vascular
  system. (It is usually about 5 liters for adults)

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• Peripheral resistance is the friction between the
  blood and the walls of blood vessels.
• Blood viscosity is the ease with which a fluid
  flows. The greater the viscosity, the greater the
  viscosity.
• Starlings law of the heart is the relationship
  between fiber length ( due to the stretching of
  the cardiac muscle cell just before contraction)
  and the force of contraction. Sooooo the more
  blood that enters the heart the stronger in
  contracts. This ensures that the volume of blood
  discharged from the heart is to the volume
  entering its chambers.

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Hypertension

• High blood pressure
• One of the more common diseases of the
  cardiovascular system.
• Hypertension can be caused by kidney disease,
  high sodium intake, obesity, psychological
  stress, and arteriosclerosis.
• Arteriosclerosis decreases the elasticity of
  arterial walls and narrows openings increases
  blood pressure.

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Hypertension Cont.

• If hypertension is left untreated it can cause
  atherosclerosis or plaque accumulation in
  arteries that can lead to a stroke.
• Plaque are deposits of fatty materials on the
  inside of the arterial walls.
• Hypertension can be treated with regular
  exercise, controlling body weight, reducing
  stress, and limiting sodium in the diet.

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13.6 Paths of Circulation

• Pulmonary circuit consists of vessels that carry
  blood from the heart to the lungs and back to the
  heart.
• Systemic circuit carries blood from the heart to
  all other parts of the body and back to the heart.

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Pulmonary Circuit

• Right ventricle
• Right and left pulmonary arteries
• Right and left lungs
• Arterioles into the alveoli (gas exchange)
• Pulmonary viens
• Left atrium

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Systemic Circuit

• Left atrium
• Left ventricle
• Aorta
• Head and body (deliver O2 and pick up CO2)
• Veins
• Right atrium

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13.7 Arterial System

• Jugular veins drain blood from the face, scalp,
  and superficial regions of the neck.
• Femoral artery located in the upper thigh supply
  blood to the tissue of the thigh, skin of the
  groin and the lower abdominal wall.