Cardiovascular System

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Cardiovascular System
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Heart Orientation
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Right
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Valve Function

• Ventricles contract, blood pumped into aorta and
  pulmonary trunk through SL valves

• Atria contract, blood fills ventricles through
  A-V valves

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One-way flow
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Thickness of Cardiac Walls
Myocardium of left ventricle is much thicker than
the right.
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THE CARDIAC CYCLE

• A cardiac cycle consists of the systole
  (contraction) and diastole (relaxation) of both
  atria, rapidly followed by the systole and
  diastole of both ventricles.
• During a cardiac cycle atria and ventricles
  alternately contract and relax forcing blood from
  areas of high pressure to areas of lower
  pressure.

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Conduction System
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Regulation of Heart Rate

• Cardiac muscle is myogenic can contract without
  nervous stimulation
• SA node is pacemaker
• Around 100 beats per minute

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Regulation of Heart Rate

• Nervous control from the cardiovascular center in
  the medulla can alter rate
• Sympathetic impulses increase heart rate
• parasympathetic impulses decrease heart rate.
• Baroreceptors (pressure receptors) detect change
  in BP
• Heart rate is also affected by hormones, age,
  gender, physical fitness, and temperature

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Blood Circulation

• Blood flow
• blue deoxygenated
• red oxygenated

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Aorta and Its Branches
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Aorta

• Largest artery of the body
• ascending aorta - 2 coronary arteries supply
  myocardium
• arch of aorta branches to the arms head
• thoracic aorta supplies branches to esophagus,
  bronchi, diaphragm, intercostal chest muscles,
  mammary gland, skin, vertebrae and spinal cord

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Coronary Circulation
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Coronary Circulation

• Coronary circulation is blood supply to the heart
• Heart as a very active muscle needs lots of O2
  and nutrients
• Many connections between arteries supplying blood
  to the same region, provide alternate routes if
  one artery becomes occluded

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Major Veins

• All empty into the right atrium of the heart
• superior vena cava drains upper body
• inferior vena cava drains lower body
• coronary sinus drains blood from heart

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Major Veins
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BLOOD VESSELS

• Blood vessels form a closed system of tubes
• Arteries carry blood from the heart to the
  tissues.
• Arterioles are small arteries that connect to
  capillaries.
• Capillaries are the site of substance exchange
  between the blood and body tissues.
• Venules connect capillaries to larger veins.
• Veins convey blood from the tissues back to the
  heart.

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Arteries

• The wall of an artery consists of three major
  layers
• Tunica interna
• simple squamous epithelium
• basement membrane
• internal elastic lamina
• Tunica media
• circular smooth muscle elastic fibers
• Tunica externa
• elastic collagen fibers

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Arteries
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Capillaries

• Microscopic vessels that connect arterioles to
  venules
• Found near every cell in the body
• Function is exchange of nutrients wastes
• Capillary walls are composed of only a single
  layer of cells (endothelium) and a basement
  membrane

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Capillaries
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Veins

• Proportionally thinner walls than same diameter
  artery
• tunica media less muscle
• lack elastic lamina
• Still adaptable to variations in volume
  pressure
• Valves are thin folds of tunica interna designed
  to prevent backflow

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Veins
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Venous Return
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Blood Distribution

• Veins function as blood reservoir
• blood is diverted from it intimes of need

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Arterial Branches of Systemic Circulation
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Veins of the Systemic Circulation

• Drain blood from entire body return it to right
  side of heart
• Deep veins parallel the arteries in the region
• Superficial veins are found just beneath the skin
• All venous blood drains to either superior or
  inferior vena cava or coronary sinus

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Blood

• Blood inside blood vessels, interstitial fluid
  around body cells, and lymph inside lymph vessels
  constitute ones internal environment.
• To obtain nutrients and remove wastes, cells must
  be serviced by blood and interstitial fluid.
• Blood, a connective tissue, is composed of plasma
  and formed elements.

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Functions of Blood

• Transportation
• O2, CO2, metabolic wastes (urea), nutrients,
  heat, antibodies hormones
• Regulation
• pH through buffers
• body temperature
• water content of cells
• Protection from disease loss of blood

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Physical Characteristics of Blood

• Thicker (more viscous) than water
• Temperature of 100.4 degrees F
• pH 7.35-7.45
• 8 of total body weight
• Blood volume
• 5 to 6 liters in average male
• 4 to 5 liters in average female

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• 55 plasma
• 91.5 water
• 7 proteins
• 1.5 other solutes
• 45 formed elements
• 99 RBCs
• lt 1 WBCs and platelets

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Blood Plasma

• 0ver 90 water
• Acts as a solvent and Regulates heat
• 7 plasma proteins
• Maintains water balance
• Albumin - Transports steroid hormones
• globulins (immunoglobulins) - antibodies bind to
  foreign substances called antigens
• Fibrinogen - for clotting
• 2 other substances
• electrolytes, nutrients, hormones, gases, waste
  products

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Formed Elements of Blood

• Red blood cells ( erythrocytes )
• White blood cells ( leukocytes )
• Cell Fragments
• Platelets (thrombocytes)

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Red Blood Cells

• Contain hemoglobin that gives blood its red color
• Biconcave disk 8 micrometers in diameter
• increased surface area/volume ratio
• flexible shape for narrow passages
• no nucleus or other organelles
• Possess glycolipids that account for blood groups
• Normal RBC count
• male 5.4 million/drop ---- female 4.8
  million/drop
• new RBCs enter circulation at 2 million/second

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Hemoglobin

• Globin protein consisting of 4 polypeptide chains
• One heme pigment attached to each polypeptide
  chain

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WHITE BLOOD CELLS

• Have surface proteins that can be used to
  identify a tissue.
• Combat inflammation and infection
• Less numerous than RBCs
• 5000 to 10,000 cells per drop of blood
• 1 WBC for every 700 RBC
• Most live only a few days

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Platelet (Thrombocyte)

• Help stop blood loss from damaged vessels by
  forming a platelet plug and contain chemicals
  that promote blood clotting
• Disc-shaped, 2 - 4 micron cell fragment with no
  nucleus
• Only live 5-9 days
• Normal platelet count is 150,000-400,000/drop of
  blood