ANS 331: Cardiovascular System
I. General
1. Function
A. Transport
a. Nutrients
b Waste
B. Blood or Lymph Fluid is transport media
2. Components
A. Vessels
a. Arteries
--Bring Blood Away from Heart
b. Capillaries
--In close contact with tissues for exchange
c. Veins
--Bring Blood Back to Heart
B. Heart
a. Pumps Blood thoughout the body
C. Lymphatic system
a. Auxillary system of vessels
b. Returns Fluids from interstitial spaces to
blood
II. Heart
1. Heart
A. Cone-Shaped, Hollow, Muscular Structure
B. Base of Cone (Dorsal-Cranial)
a. Enter Large Arteries and Veins
C. Other end is the Apex of Heart (Ventral-Caudal)
D. Located in Thoracic Cavity
2. Pericardium
A. Connective Tissue Sac in which the Heart Lies
a. Two Layers
i. Visceral (Epicardium)
ii. Parietal
B. Slightly Fluid Filled
a. Lubrication
C. Can become inflamed
a. Hardware Disease in Cattle
b. Washing Machine Sounds
3. Myocardium
A. Muscular Part of Heart
B. Forms walls of Chambers
C. Four Chambers
a. Left and Right Atria
--Receive Blood From Veins
--Left from Pulmonary Vein
--Right from Vena Cava
b. Left and Right Ventricles
--Receive Blood From Atria
--Left Pump Blood through Aorta
--Right Pump Blood throught Pulmonary Artery
4. Endocardium
A. Innermost Layer
B. Endothelium
4. Heart Valves
A. Atrioventricular Valves (A-V valves)
a. Located between Antria and Ventricles
b. Right valve is tricuspid
c. Left valve is bicuspid
--also called mitral valve
d. Prevent expulsion of ventricular blood in
the atria
during heart contraction
e. Cordae Tendinae keep valves from inverting
B. Semilunar Valves
a. Located at exits of Ventricles
b. Both Tricuspid
c. Right Valve
--Pulmonary Semilunar
d. Right Valve
--Aortic Semilunar
5. Blood flow through the Heart
A. Vena Cava
a. Venous Blood
i. Lost Oxygen
ii. Gained Carbon Dioxide
B. Right Atrium
C. Right Ventricle
D. Pulmonary Artery
a. Still Venous Blood
E. Lungs
F. Pulmonary Vein
a. Oxygenated (Arterial Blood)
G. Left Atrium
H. Left Ventricle
I. Aorta
III. Blood Vessels
1. General Structure
A. Continuation of Heart
a. Lined with endothelium
2. Order
A. Arteries
B. Arterioles
C. Capillaries
D. Venules
E. Veins
3. Arteries
A. Most Mass
B. Elastic C.T.
a. Help with pumping
C. Smaller arteries gain more smooth muscle
a. Control Blood Flow
4. Arterioles
A. Muscular just prior to Capillaries
a. Precapillary Sphincters
b. Regulate Blood Flow to Capillary beds
5. Capilaries
A. Endothelial Tubes
B. Contain Slit Pores (Clefts)
a. Diffusion
b. Transport of small particles (<4 nm)
C. Pinocytotic Vescicles
a. Transport of larger particles (Proteins)
6. Venules and Veins
A. Contain Smooth Muscle
a. Increase resistance to regulate blood flow
b. Increase Blood Pressure
B. Backflow prevented by Valves
5. Blood Circulatory System
A. Systemic Circulation
A. Whole body except Lungs
B. Aorta
a. First Branch--Coronary Arteries
(to Heart)
b. Second Branch--Carotids (to Brain)
B. Pulmonary Circulation
A. Lungs
C. Portal Systems
A. Vein Capillary Vein
B. Few Examples
a. Hepatic Portal System
--Liver
--Blood Cleansing (Kuppfer Cells)
b. Hypothalamic-Pituitary Portal System
--Hormones Transport
IV. Lymphatic System
1. Lymph Vessels
A. Blind beginnings in interstitial space
a. Lymph Capillaries
B. Vessels tend to parallel veins
C. A few large vessels empty into veins
D. Contain Valve to inhibit backflow
2. Lymph
A. Fluid of Lymph Vessels
B. Composition is similar to interstitial fluid
C. Return proteins to Veins
a. Proteins don't normally diffuse well back
through the capillaries
D. Movement through vessels is controlled by:
a. Smooth muscle contraction
b. Skeletal muscle movement
--Inactive people can get edema
3. Lymph Nodes
A. Nodular structures located along lymph vessels
B. Functions:
a. Lymphocyte production
b. Clean-up lymph
--Contain Fixed Macrophages
C. Enlarge during infection
a. Entrapment of bacteria and infection
by-products
b. Increase Lymphocyte production
D. Cancer cells can get intrapped
a. Metastisis
4. Spleen
A. Larges lymphoid organ of the body
B. Circulates blood rather than lymph
C. Functions
a. Filtration
--Removes old red blood cells
b. Lymphocyte production
c. RBC storage and release
--Spleen release can increase PCV 10%
V. Cardiac Contractility
1. Origin of a Heart Beat
A. Sinoatrial (S-A) Node
a. Pacemaker
b. Specialized cardiac muscle cells in the
right atrium
--Fire rhythmically
2. Conduction of the Impulse
A. Two Syncytia
a. Atrial Syncytium
b. Ventricular Syncytium
c. Arrangement of muscle fibers that are
fused to form one unit
d. Separated by Fibrous ring around A-V valve
i. Insulator
ii. Allows for independent contraction
--Needed for proper heart function
B. Purkinje Fibers
a. Facilitate rapid conduction
b. Coordinate conduction between syncytia
c. Conduction pathway from atria to ventricles
C. Conduction
a. S-A node stimulates internodal pathways
i. Stimulate atrial depolarization
ii. Facilitated by intercalated disks
b. A-V node stimulated
i. Slow impulse to 10% normal
depolarization
--Smaller Purkinje Fibers
ii. Permits delay in ventricular
depolarization
c. Right and Left Bundle Fibers Stimulated
i. Large Purkinje Fibers
--Signal increase 2 to 3 times
faster than normal cardiac muscle
depolarization
ii. Stimulate coordinated Ventricular
contraction
D. Cardiac vs. Skeletal Muscle
a. Contraction Slower
b. Refractory period longer
i. Complete impulse travel through
each syncytium
ii. Complete Relaxation
E. Fibrillation
a. Contraction and Relaxation occur in same
syncytium
b. Defibrillation (Electrical Impulse)
--Cause whole heart to depolarize
--Starts new cycle with S-A node
depolarization
3. Cardiac Cycle
A. Sequence of events that occur during one complete
heart beat
a. One "Lub-Dup"
B. Two periods
a. Diastole
i. Relaxation of heart chamber
ii. Filling of chamber
b. Systole
i. Contraction of heart chamber
ii. Process of emptying
c. Usually refer to ventricular diastole
and systole
VI. Electrocardiogram
1. General
A. Voltage changes in the heart are conducted through
body fluids
a. Body Fluids act as conductors
B. Measured by electrocardiogram (EKG or ECG)
a. Amplifies voltage changes
b. Different placement of leads can give
important information about different
areas of the heart
--Lead II most common (Right arm/Left Leg)
c. Measurements made on recorder
--Show up as waves (or blips)
2. Wave Forms
A. P wave
a. Depolarization of atria
b. Atrial Contraction starts
B. QRS Complex
a. Ventricular Depolarization
b. Ventricular Contraction starts
c. Atrial Repolarization
C. T wave
a. Ventricular Repolarization
3. Isoelectric line
A. Line in which waves occur
B. Space between and within waves can be diagnostic
a. Long QRS = Ventricular Hypertrophy
b. Short ST segment = Hypoxia
VII. Heart Sounds
1. Caused by closing of valves
A. A-V valves
a. First sound--"Lub"
B. Semilunar valves
a. Second sound--"Dup"
C. Third sound
a. Hard to hear
b. Rapid Filling of Ventricles
D. Murmurs
a. "Shhh" sound after "Lub" or "Dup"
b. Leakage from valve
VIII. Heart Rate and its Control
1. Metabolic Rate
A. Smaller Animals faster rate (beats per minute)
than Larger animals
B. Younger faster than Older animals
2. Autonomic Nervous System
A. Sympathetic--Increases rate
B. Parasympathetic--Decreases rate
3. Autoregulation
A. Starling's Law
a. Larger Volume of Diastole, Greater Strength
of Contraction
4. Reflexes
A. Stretch and Pressure Receptors cause heart to
increase or decrease rate
a. Carotid Sinuses
b. Aortic Arch
c. Right Atrium
IX. Blood Pressure
1. Pressure Generation and Flow
A. Aorta has Highest Pressure
a. Due to Elastic Connective Tissue in the
Artery Walls
i. Rebound Tendency
b. Pressure exerted even after ventricular
contraction
c. Permits continuous flow through body
B. Vena Cava has Lowest Pressure
2. Systolic and Diastolic Pressures
A. Systolic Pressure
a. Pressure at peak of Ventricular Systole
(Contraction)
B. Diastolic Pressure
a. Pressure at Ventricular Diastole
(Relaxation)
3. Measurements
A. Measures
--Units = mm Hg or torr
a. Systolic/Diastolic
b. Pulse Pressure = Systolic - Diastolic
c. Mean Blood Pressure
= Diastolic + 1/3 Pulse Pressure
B. Animals are difficult to measure
a. Humans--Syphgomanometer
b. Animals--Cannulation
()
X. Blood Flow
1. Factors
A. Pressure
a. Difference between intake and output
b. Heart and Elasticity of Arteries
B. Resistance
a. Vasoconstriction
--increases resistance
b. Vasodilation
--decreases resistance
2. Autoregulation
A. Controlled by oxygen
a. Dilation--Low oxygen
b. Constriction--High oxygen
3. Cardiac Output and Blood Diversion
A. Resting
a. Blood is pumped mostly to internal organs
(Kidneys, Intestine)
B. Increase Activity (Exercise)
a. Blood is pumped to skeletal muscle
4. Breathing and Blood Flow
A. Breathing helps pump blood through vena cava
a. Increases thoracic cavity pressure
5. Circulation Time
A. Time it takes for blood to pump from left ventricle
to right atrium
B. Range = 40 to 60 seconds
XI. Capillary Dynamics
1. The Physical Factors associated with the exchange between
the blood and interstitial fluid
A. Simple Diffusion
a. Lipid Soluble
--Oxygen, Carbon Dioxide
B. Diffusion through Slit Pores (Clefts)
a. Water
b. Small lipid-insoluble
--Electrolytes, glucose, urea
c. Large lipid-insoluble
--Proteins
--Diffuse through slit pores with great
difficulty
2. Diffusion and Bulk Flow
A. Water exchanged in capillaries 80X as it
transverses capillaries
B. Bulk Flow
a. Substances transported by Pressure
i. Osmotic
ii. Hydrostatic
3. Mechanisms of Bulk Flow
A. Capillary Pressure
a. Hydrostatic Pressure of Capillary
i. Arterial end = 25 mm Hg
ii. Venous end = 10 mm Hg
B. Interstitial Fluid Pressure
a. Hydrostatic Pressure of Interstitial Fluid
i. -6 mm Hg
b. Vacuum created by return of fluids to veins
and lymphatics
C. Plasma Colloidal Osmotic Pressure
a. Osmotic Pressure of the Plasma
i. 28 mm Hg
b. Due to Proteins and Cations
D. Interstitial Fluid Colloidal Osmotic Pressure
a. Osmotic Pressure of the interstitial Fluid
b. Due to Proteins in Interstitial Fluid that
haven't been returned to blood via
Lymph Vessels
E. Flow
a. Arterial End
--Bulk flow towards interstitial fluid
b. Venous End
--Bulk flow toward capillaries
4. Capillary Imbalances
A. Fluid accumulation in interstitial space = edema
a. High Capillary Pressure
b. Low Blood Protein
c. Lymphatic Blockage
d. Increases Porosity
--Protein escapes
~~~~~Revised 10/16/98~~~~~ TAW