CIRCULATION
CIRCULATION
• THE CIRCULATORY SYSTEM ASSOCIATES
INTIMATELY WITH ALL BODY TISSUES
– CIRCULATORY SYSTEM
• A SYSTEM OF INTERNAL TRANSPORT; TRANSPORTS
OXYGEN AND CARBON DIOXIDE, DISTRIBUTES
NUTRIENTS TO BODY CELLS, AND CONVEYS THE WASTE
PRODUCTS OF METABOLISM TO SPECIFIC SITES FOR
DISPOSAL
CIRCULATION
• SEVERAL TYPES OF INTERNAL TRANSPORT HAVE
EVOLVED IN ANIMALS
– SIMPLE ANIMALS HAVE NO TRUE CIRCULATORY
SYSTEM (WHY DON’T THEY NEED ONE??)
• EX. HYDRA
– BLOOD
• SPECIALIZED CIRCULATORY FLUID FOUND IN MORE
COMPLEX ANIMALS
– TWO BASIC TYPES OF SYSTEMS
• OPEN CIRCULATORY SYSTEM
• CLOSED CIRCULATORY SYSTEM
CIRCULATION
• TWO BASIC TYPES OF SYSTEMS
CIRCULATION
• TWO BASIC TYPES OF SYSTEMS
– OPEN CIRCULATORY SYSTEM
• BLOOD LEAVES THE VESSELS AND BATH THE CELLS
DIRECTLY (EX. GRASSHOPPER)
– CLOSED CIRCULATORY SYSTEM (A.K.A.
CARDIOVASCULAR SYSTEM)
• CONSISTS OF A HEART AND TUBE-LIKE VESSELS; THE
BLOOD IS ALWAYS CONFINED TO THESE VESSELS (EX.
FISH, HUMANS)
CIRCULATION
• CLOSED CIRCULATORY SYSTEM
– THREE KINDS OF VESSELS
• ARTERIES
– CARRY BLOOD AWAY FROM THE HEART
– ARTERIOLES  SMALL VESSELS, OFF ARTERIES, THAT GIVE RISE
TO CAPILLARIES
• VEINS
– CARRY BLOOD TO THE HEART
– VENULES  RESULT OF CONVERGING CAPILLARIES THAT
EVENTUALLY FORM VEINS
• CAPILLARIES
– CONVEY BLOOD BETWEEN ARTERIES AND VEINS WITHIN EACH
ORGAN
– CAPILLARY BEDS  NETWORKS OF CAPILLARIES THAT INFILTRATE
EVERY ORGAN AND TISSUE IN THE BODY
CIRCULATION
• VERTEBRATE CARDIOVASCULAR SYSTEMS
REFLECT EVOLUTION
CIRCULATION
• VERTEBRATE CARDIOVASCULAR SYSTEMS
– PULMONARY CIRCUIT
• CARRIES BLOOD BETWEEN THE HEART AND THE GAS
EXCHANGE TISSUES IN THE LUNGS
– SYSTEMIC CIRCUIT
• CARRIES BLOOD BETWEEN THE HEART AND THE REST
OF THE BODY
CIRCULATION
• HUMAN HEART
AND
CARDIOVASCULAR
SYSTEM TYPIFY
THOSE OF
MAMMALS
CIRCULATION
• FOLLOWING THE PATH OF BLOOD
–
–
–
–
–
–
–
–
–
–
RIGHT VENTRICLE
*PULMONARY ARTERIES*
CAPILLARIES IN LUNGS
*PULMONARY VEIN*
LEFT ATRIUM
LEFT VENTRICLE
AORTA
ARTERIES BRANCH OFF AORTA
SUPERIOR VENA CAVA / INFERIOR VENA CAVA
RIGHT ATRIUM
– *VAVA L VAVA*
CIRCULATION
• THE STRUCTURE OF BLOOD
VESSELS FITS THEIR
FUNCTION
– ARTERIES
• THICKEST
– VEINS
• VALVES
– CAPILLARIES
• THINNEST
CIRCULATION
• THE HEART CONTRACTS AND RELAXES RHYTHMICALLY
– CARDIAC CYCLE
• A COMPLETE SEQUENCE OF
FILLING AND PUMPING OF
THE HEART
• DIASTOLE
– ENTIRE HEART IS RELAXED; BLOOD
FLOWS INTO ALL FOUR
CHAMBERS
» AV VALVES ARE OPEN,
ALLOWING BLOOD TO GO
FROM ATRIUM TO VENTRICLES
• SYSTOLE
– BRIEF CONTRACTION THAT FORCES
ALL BLOOD INTO VENTRICLES (0.1 SEC)
– VENTRICLES CONTRACT FOR ABOUT
0.3 SEC, CLOSING AV VALVES AND OPENING
SEMI-LUNAR VALVES WHICH PUMPS
BLOOD INTO ARTERIES
CIRCULATION
• THE HEART CONTRACTS AND RELAXES RHYTHMICALLY
– CARDIAC OUTPUT
• THE VOLUME OF BLOOD PER
MINUTE THAT THE LEFT
VENTRICLE PUMPS INTO THE
SYSTEMIC CIRCUIT
– VALVES PREVENT BACKFLOW
AND KEEP BLOOD FLOWING
IN RIGHT DIRECTION
• RESPONSIBLE FOR “LUB-DUB”
SOUND HEART MAKES
• WHEN DEFECTIVE, RESULTS IN
A MURMUR
– EXTRA HEART SOUNDS
CIRCULATION
• THE PACEMAKER SETS THE TEMPO OF THE
HEARTBEAT
CIRCULATION
• THE PACEMAKER SETS THE TEMPO OF THE HEARTBEAT
– PACEMAKER  A.K.A. SA (SINOATRIAL) NODE; SPECIALIZED
REGION OF CARDIAC MUSCLE THAT MAINTAINS THE
HEARTS PUMPING RHYTHYM BY SETTING THE RATE AT
WHICH ALL THE MUSCLE CELLS OF THE HEART CONTRACT
• PACEMAKER GENERATES ELECTRICAL SIGNALS
• SIGNALS SPREAD THROUGHOUT ATRIA; 0.1 SEC TO REACH AV
(ATRIOVENTRICULAR) NODE
• SPECIALIZED MUSCLE FIBERS RELAY SIGNALS AND CAUSE
VENTRICLE CONTRACTION THAT PUMPS BLOOD
– ARTIFICIAL PACEMAKER
• A TINY ELECTRONIC DEVICE SURGICALLY IMPLANTED NEAR THE AV
NODE; EMIT ELECTRICAL SIGNALS THAT TRIGGER NORMAL
HEARTBEATS
CIRCULATION
• WHAT IS A HEART ATTACK?
– HEART ATTACK
• FAILURE OF THE HEART TO FUNCTION PROPERLY; DUE TO LACK OF
OXYGEN BEING DELIVERED TO CARDIAC CELLS
– CARDIOVASCULAR DISEASE
• DISEASES OF HEART AND BLOOD VESSELS; ACCOUNTS FOR 40% OF
ALL DEATHS IN U.S.
– ATHERIOSCLEROSIS
• GROWTH OF PLAQUE
DEVELOPS ON THE INNER
WALLS OF THE ARTERIES,
NARROWING THE PASSAGES
THROUGH WHICH BLOOD
CAN FLOW
CIRCULATION
• BLOOD EXERTS PRESSURE ON VESSEL WALLS
– BLOOD PRESSURE
• THE FORCE THAT BLOOD EXERTS AGAINST THE WALLS
OF OUR BLOOD VESSELS
– PULSE
• THE RHYTHMIC STRETCHING OF
THE ARTERIES
CIRCULATION
• MEASURING BLOOD PRESSURE CAN REVEAL
CARDIOVASCULAR PROBLEMS
– HYPERTENSION
• HIGH BLOOD
PRESSURE; MAY
INDICATE A
SEVERE
CARDIOVASCULAR
DISEASE
CIRCULATION
• SMOOTH MUSCLE CONTROLS
THE DISTRIBUTION OF BLOOD
– SPHINCTERS EXIST THAT LIMIT
BLOOD FLOW THROUGH
CAPILLARY BEDS IF BLOOD IS
NOT NEEDED IN THOSE AREAS
(EX. DIGESTIVE TRACT DURING
EXERCISE)
CIRCULATION
• CAPILLARIES ALLOW THE TRANSFER OF
SUBSTANCES THROUGH THEIR WALLS
– THE THIN WALLS MAKE THIS THE ONLY VESSEL
WHERE TRANSFER OF SUBSTANCES CAN TAKE
PLACE
CIRCULATION
• BLOOD CONSISTS OF CELLS SUSPENDED IN
PLASMA
CIRCULATION
• BLOOD CONSISTS OF CELLS SUSPENDED IN
PLASMA
– ADULT HUMAN ON AVERAGE HAS 4 – 6 LITERS OF
BLOOD
– 4 PARTS TO BLOOD
•
•
•
•
PLASMA
RED BLOOD CELLS
WHITE BLOOD CELLS
PLATELETS
CIRCULATION
• PLASMA
– LIQUID MADE UP OF 90% WATER, 10%
INORGANIC SALTS
• 55% OF BLOOD IS PLASMA
• WORKS TO MAINTAIN OSMOTIC BALANCE AND PH
CIRCULATION
• RED BLOOD CELLS
– A.K.A. ERYTHROCYTES
– MOST NUMEROUS BLOOD CELLS
– LACK NUCLEI AND MITOCHONDRIA
– FORMED IN BONE MARROW
– CYCLE FOR 3-4 MONTHS BEFORE BROKEN DOWN
AND RECYCLED IN THE LIVER
– *ANEMIA*
• AN ABNORMALLY LOW AMOUNT OF HEMOGLOBIN OR
A LOW NUMBER OF RED BLOOD CELLS
CIRCULATION
• WHITE BLOOD CELLS
– A.K.A. LEUKOCYTES
– HELP DEFEND THE BODY
– 5 TYPES
• BASOPHILS
– RELEASE CHEMICALS TO FIGHT INFECTION
• NEUTROPHILS
– PHAGOCYTES
• MONOCYTES
– PHAGOCYTES
• EOSINOPHILS
– KILL PARASITIC WORMS, HELP REDUCE ALLERGIES; NOT FULLY UNDERSTAND
• LYMPHOCYTES
– KEY CELL IN IMMUNITY
– WILL DISCUSS IN MORE DETAIL DURING “IMMUNE SYSTEM”
CIRCULATION
• PLATELETS
– BITS OF CYTOPLASM PINCHED OFF FROM LARGE
CELLS IN THE BONE MARROW
– IMPORTANT IN BLOOD CLOTTING
CIRCULATION
• BLOOD CLOTTING
– PLATELETS AND THE PLASMA PROTEIN
FIBRINOGEN ACT AS SEALANTS
– PROTHROMBIN IS CONVERTED TO THROMBIN
WHICH CONVERTS FIBRINOGEN TO FIBRIN
• FIBRIN
– THREAD-LIKE PROTEIN THAT TRAPS BLOOD CELLS; FORMING
PATCH UNTIL CONNECTIVE TISSUE CAN HEAL
– CLOTTING MECHANISM DEFECTS CAN BE SERIOUS
• HEMOPHILIA
• THROMBOSIS CLOTS WHEN THERE IS NO INJURY
CIRCULATION
• STEM CELLS OFFER A POTENTIAL CURE FOR
LEUKEMIA AND OTHER BLOOD CELL DISEASES
– STEM CELLS
• UNSPECIALIZED CELLS
– LEUKEMIA
• CANCER OF THE WHITE BLOOD CELLS (LEUKOCYTES)
CIRCULATION
• SPEAKING OF DISEASES…HOW DOES THE
HUMAN BODY PROTECT ITSELF??
• THE IMMUNE
SYSTEM IS
NEXT!!!