Transcript Chapter 12

Lecture PowerPoint to accompany
Inquiry into Life
Twelfth Edition
Sylvia S. Mader
Chapter 12
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
12.1 The Blood Vessels
• Three Types of Blood Vessels
– Arteries
(carry blood away from the heart)
– Capillaries (permit exchange of materials with tissues)
– Veins
(carry blood toward the heart)
12.1 The Blood Vessels
• The Arteries
– Three layers to an arterial wall
• Inner layer - simple squamous epithelium with basement
membrane
• Middle layer- thickest layer, contains smooth muscle
• Outer layer - fibrous and loose connective tissue
Blood Vessels
12.1 The Blood Vessels
• The Capillaries
– Capillaries join arterioles to venules
– Capillary walls are one-cell in thickness
– Capillaries form vast networks in all regions of the
body
– Capillary beds can be bypassed by a arteriovenous
shunt
Anatomy of a Capillary Bed
12.1 The Blood Vessels
• The Veins
– The walls of veins are structured similarly to the walls
of arteries, but there is less smooth muscle and
connective tissue in veins.
– Veins often have valves to prevent the backflow of
blood.
– Veins have a greater capacity to expand, they serve
as blood reservoir.
12.2 The Heart
• The heart is a muscular organ that lies between
the lungs directly behind the sternum.
– Myocardium: The major portion of the heart that
consists mainly of cardiac muscle.
– Pericardium: A serious membrane that surrounds the
heart.
– Endocardium: A membrane consisting of connective
tissue and endothelium that lines the inner surface of
the heart.
12.2 The Heart
• The Human Heart
• Four-chambers
• Two atria and two ventricles
• A septum separates the right and left sides
• Four valves prevent the backflow of blood
• Two atrioventricular valves
• Two semilunar valves
External Heart Anatomy
12.2 The Heart
• The Human Heart Continued
– Heart is described as a double pump
• Right ventricle sends oxygen-poor blood into the pulmonary
circuit
• Left ventricle sends oxygen-rich blood into the systemic
circuit
– Blood must travel through the lungs to go from the
right side of the heart to the left side
– Oxygen-rich blood does not mix with oxygen-poor
12.2 The Heart
• Path of Blood Through the Heart
Vena cava right atrium tricuspid valve
right ventricle pulmonary semilunar valve
pulmonary trunk pulmonary arteries lungs
pulmonary veins left atrium bicuspid valve left
ventricle aortic semilunar valve aorta body
Internal View of the Heart
12.2 The Heart
• The Heartbeat (Cardiac Cycle)
• Each time the heart beats:
– The two atria contract simultaneously
– Then the two ventricles contract simultaneously
– All the chambers then relax
• Systole: Contraction of the heart muscle
• Diastole: Relaxation of the heart muscle
12.2 The Heart
• The Heartbeat
– Heart Sounds
• Described as a “lup-dup” sound
– “Lup” sound - atrioventricular valves closing
– “Dup” sound - semilunar valves closing
• A heart murmur (swishing sound) may be due to a leaky
valve
Heart Sounds / Cardiac Cycle
12.2 The Heart
• Intrinsic Control of Heartbeat
– The SA (sinoatrial node)
• Located in the upper portion of the right atrium wall
• Initiates the heartbeat, sends out an excitatory impulse every
0.85 seconds
• This causes the atria to contract
• The excitatory impulses travels to the AV node
• Called the “pacemaker” of the heart
Conduction System of the Heart
12.2 The Heart
• Intrinsic Control of Heartbeat
– The AV (atrioventricular node)
• Located in the base of the right atrium wall
• When impulses (that originated in the SA node) reach the AV
node, there is a slight delay that allows the atria to finish their
contraction
• An impulse travels from the AV node through the branches of
the atrioventricular bundle before reaching the Purkinje
fibers.
• Purkinje fibers are specialized muscle cells that cause the
ventricles to contract.
12.2 The Heart
• Extrinsic Control of Heartbeat
– Medulla oblongata (brain)
• Influences heart beat via the autonomic nervous system
– Sympathetic division increases heart rate
– Parasympathetic system decreases heart rate
12.2 The Heart
• Electrocardiograms (ECG)
– A recording of the electrical changes
occurring in the heart
An Electrocardiogram
• P Wave occurs just prior
to atrial contraction
• QRS complex occurs just
prior to ventricular
contraction
• T wave occurs after
ventricular contraction
12.3 The Vascular Pathways
• The cardiovascular system has two
circuits:
– The Pulmonary Circuit
• Circulates blood through the lungs
– The Systemic Circuit
• Circulates blood through the rest of the body
12.3 The Vascular Pathways
• The Pulmonary Circuit
– Blood from the body
collects in the right atrium
– Right Atrium
Right
Ventricle Pulmonary
Arteries
Arterioles
Capillaries
Venules
Pulmonary Veins
Left
atrium
12.3 The Vascular Pathways
• The Systemic Circuit
– Blood leaves the left
ventricle, travels through
the body and is returned to
the heart
– aorta
arteries
arterioles
capillaries
venules
veins
vena cava
12.3 The Vascular Pathways
12.3 The Vascular Pathways
Coronary arteries supply
blood to the heart muscle.
In the hepatic portal system,
blood travels from the
intestines through the liver and
to a vena cava.
12.3 The Vascular Pathways
• The beat of the heart supplies pressure that keeps blood
moving in the arteries
– Systolic Pressure results from blood forced into the arteries
during ventricular systole.
– Diastolic Pressure is the pressure in the arteries during
ventricular diastole.
• Blood pressure
– Normally measured with a sphygmomanometer on the brachial
artery.
– Expressed in the form: Systolic “over” Diastolic (120/80)
• Skeletal muscle contraction pushes blood in the veins
toward the heart.
Velocity and Blood Pressure Related to
Vascular Cross-Sectional Area
Cross Section of Valve in a Vein
12.4 Blood
• Plasma
– Liquid portion of the blood
• Formed Elements
– Red blood cells
– White blood cells
– Platelets
12.4 Blood
• Blood has:
– Transport functions
– Regulatory functions
– Protective functions
Composition of Blood
12.4 Blood
• Plasma
– Contains inorganic and organic substances dissolved
or suspend in water
– Plasma proteins
• Various functions
– Transport of substances, blood clotting, fighting disease
• Help maintain blood volume
12.4 Blood
• Red Blood Cells (Erythrocytes)
–
–
–
–
Manufactured in red bone marrow
4-6 million per mm3 of whole blood
Shape is biconcave disc, they also lack a nucleus
Contain hemoglobin
• Red iron-containing pigment
• Heme portion binds oxygen
• Carbon monoxide (a pollutant) can also bind at heme sites
– Combines more readily than oxygen
– Can be lethal
Physiology of Red Blood Cells
12.4 Blood
• Red Blood Cells Continued
– Red blood cells last around 120 days and then are
destroyed in the liver and spleen
– Too few red blood cells results in anemia
– A lack of iron also causes anemia
12.4 Blood
• White Blood Cells (Leukocytes)
– Nucleated
– Lack Hemoglobin
– 4,000 - 11,000 cells per mm3 of whole blood
– Role is to fight infection and provide immunity
12.4 Blood
• White Blood Cells
– Granulocytes-have visible granules in cytoplasm
• Neutrophils- most abundant leukocyte, phagocytic
• Basophils-granules stain deep blue and release histamine
• Eosinophils-granules stain red, fight parasitic worms
– Agranulocytes- lack visible granules
• Lymphocytes-T and B cells, play roles in immunity
• Monocytes-largest WBC’s, phagocytic
12.4 Blood
• White Blood Cells
– The number or cell count of specific types of
leukocytes can be used in diagnosing disease.
• Infectious mononucleosis
• AIDS
• Leukemia
12.4 Blood
• The Platelets and Blood Clotting
– The Platelets
• Form as a result of fragmentation of large cells in the red
bone marrow
• 150,000-300,000 per mm3 of whole blood
• Involved in the process of clotting
12.4 Blood
• The Platelets and Blood Clotting
– Blood Clotting
• Platelets form a plug for immediate stoppage of bleeding
• Vessels release prothrombin activator and injured tissues
release thromboplastin
– Thromboplastin stimulates further release of prothrombin
activator
•
•
•
•
– Requires calcium
Prothrombin activator activates the plasma protein
prothrombin to thrombin
Thrombin activates fibrinogen to fibrin which forms a clot
Clot is composed of network of fibrin threads and trapped
cells
As damage heals, plasmin breaks down the clot
Blood Clotting
12.4 Blood
• The Platelets and Blood Clotting
– Hemophilia
• Inherited disorder
• Deficiency in a clotting factor
• Internal bleeding can cause serious damage to cells and
tissues
• Hemophilia is treated by blood transfusions and injections of
clotting factors.
12.4 Blood
• Bone Marrow Stem Cells
– Cells which are capable of dividing and differentiating
into particular cell types
• Red and white blood cells
• Some may even be able to give rise to liver, bone, fat,
cartilage, heart, and nerve cells
• May provide solutions for diseases such as Alzheimer’s and
Parkinson’s
– Many researchers prefer to work with embryonic stem
cells since they are totipotent (can become any cell
type)
Blood Cell Formation in
Red Bone Marrow
12.4 Blood
• Capillary Exchange
– Two forces control movement through capillary wall
• Osmotic pressure tends to cause water to move from tissues
to blood; due to presence of plasma proteins and salts
• Hydrostatic pressure (blood pressure) tends to cause water
to move from blood to tissues
– At arterial end of capillary hydrostatic pressure is
higher so water moves out-contributes to tissue fluids
– Midway through capillary these forces are equalized
so no net movement of water
• Solutes now move down their gradients
12.4 Blood
• Capillary Exchange
– At the venous end osmotic pressure is greater than
hydrostatic pressure so water moves into capillary
– Almost the same amount of water gets reabsorbed
that left the capillary at the arterial end
– The small amount of fluid remaining behind can be
absorbed by lymphatic vessels
Capillary Exchange in the
Systemic Circuit
Lymphatic Capillaries
12.5 Cardiovascular Disorders
• Atherosclerosis
– Plaque formation in vessels caused by fats and
cholesterol
– Interferes with blood flow
– May be hereditary
– Prevention
• Diet high in fruits and vegetables
• Low in saturated fats and cholesterol
– Plaques can cause clots to form thrombus
• If clot breaks loose it becomes a thromboembolism
12.5 Cardiovascular Disorders
• Stroke, Heart Attack, and Aneurysm
– Stroke (CVA): small cranial arteriole bursts or
becomes blocked
• Lack of oxygen to brain can cause paralysis or death
• Warning signs: numbness in hands or face, difficulty
speaking, temporary blindness in one eye
– Heart attack (myocardial infarction)
• A portion of the heart muscle deprived of oxygen
• Angina pectoris-chest pain from partially blocked coronary
artery
• Heart attack occurs when vessel becomes completely
blocked
12.5 Cardiovascular Disorders
• Stroke, Heart Attack, and Aneurysm
– Aneurysm- ballooning of a blood vessel
• Most often in abdomen or brain
• Atherosclerosis and hypertension can weaken walls of
vessels leading to an aneurysm
• Bursting of blood vessels can be fatal
12.5 Cardiovascular Disorders
• Coronary Bypass
Operations
– Bypass blocked areas
of coronary arteries
– Can graft another
vessel to the aorta and
then to the blocked
artery past the point of
blockage
– Gene therapy may be
a future treatment
12.5 Cardiovascular Disorders
• Clearing Clogged
Arteries
– Angioplasty
• Catheter is placed in
clogged artery
• Balloon attached to
catheter is inflated
• Increases the lumen of
the vessel
• Stents can be placed to
keep vessel open
12.5 Cardiovascular Disorders
• Heart Transplants and Artificial Hearts
– Usually successful but shortage of donors
– LVAD-left ventricular assist device
•
•
•
•
Alternative to heart transplant
Tube passes blood from left ventricle to the LVAD
Blood is pumped to the aorta
LVAD are used as temporary measures until a donor heart
becomes available
– TAH-total artificial heart
• Generally only used to very ill patients
• Survival rates are not good but may be because patients are
so ill
12.5 Cardiovascular Disorders
• Hypertension (High blood pressure)
– Affects about 20% of all Americans
– Usually caused by a narrowing of the arteries
– Age, gender, and lifestyle can influence blood
pressure
• Obesity
• Smoking
• High dietary salt intake
– Medications can be used to treat this disease