-
Blood Pressure
Force the blood exerts against the inner walls of all blood vesse
-
Arterial Blood Pressure
- Rises when the ventricles contract
- Falls when the ventricles relax
-
Systolic pressure
Maximum pressure during ventricular contraction
-
Diastolic pressure
Minimum pressure when the ventricles relax
-
Creation of a pulse
- Blood enters the arterial system during ventricular systole, the elastic walls of the arteries stretch
- Pressure begins to dec. almost immediately at end of the ventricular contraction & the artery walls recoil
- Strong radial pulse indicates high b.p. & weak radial pulse indicates low b.p.
-
Factors that Influence Arterial B.P.
Heart Action
- Heart rate = Pulse rate
- Stroke vol =Vol of blood discharged frm the ventricle w/ each contraction, abt 70 ml for an avg. male @ rest
- Cardiac output = Vol of blood discharged frm the ventricle in 1 min = Stroke vol X H.R.
-
Factors that Influence Arterial B.P.
Blood Volume
- Blood vol = Vol of formed elements + Vol of plasma
- ~5 liters for avg adult
- Directly proportional to vol of blood w/in cardiovascular sys
- Changes in vol initially change b.p., then body attempts to return body to normal b.p.
-
Factors that Influence Arterial B.P.
Peripheral resistance
- Cause=friction btw blood & walls of blood vessels
- Slows blood flow
- Must overcome by b.p. so blood continues to flow
- Contraction of walls of arteries & arterioles raises b.p., but helps to move blood against peripheral resistance
- Elastic recoil of artery walls maintains some b.p. during diastole & converts intermittent flow of blood in arteries to smoother flow in capillaries
-
Factors that Influence Arterial B.P.
Viscosity of blood
- Ease of flow of blood components past each other
- Blood cells and some blood proteins increase viscosity
-
Control of Blood Pressure
- B.P. is determined by cardiac output (CO) & peripheral resistance (PR)
- BP = CO x PR
- Maintenance of b.p. requires regulation of CO & PR
- C.O. limited by venous return to ventricles
-
Control of Blood Pressure
Cardiac Output (CO)
- Can be influenced by contractility, the force produced during a contraction when a given vol of blood is in the ventricle immediately prior to contraction
- Influenced by autonomic nervous sys & hormones
- EX: epinephrine, norepnephrine, & thyroid hormones
- Influenced by arterial blood pressure detected by baroreceptors in the aortic arch & the carotid sinuses
-
Venous Blood Flow
- B.P. decreases as the blood moves through the arterial sys & into the capillary network, so little pressure remains at the venular ends of the capillaries
- Only partly a directresult of heart action
- Dependent on:
- Skeletal Muscle Contraction
- Breathing
- Venoconstriction
- Only partly a direct
- result
of heart action
-
Central Venous Pressure
- Pressure in the right atrium
- All veins, except those returning to the heart from the lungs, drain into the right atrium
- Affects pressure within the peripheral veins
- Weak heart beat increases central venous pressure
- Increase in central venous pressure causes blood to back up into the peripheral veins
-
Paths of Circulation
2 Major pathways
- The pulmonary circuit
- The systemic circuit
-
Paths of Circulation
Pulmonary Circuit
- Between heart & lungs only
- Pulmonary trunk divides into lt & rt pulmonary arteries, which divide into lobar branches, which enter the lungs
- After further divisions, arterioles continue into
- capillary networks associated w/ the walls of the alveoli, aka, air sacs
- Gas exchange occurs btw air in alveoli & blood in the capillary networks
- Slightly different hydrostatic osmotic forces push fluid
- out of the capillary and into alveolar tissues
- Epithelial lining of alveoli prevents transfer of ions & H20 frm the interstitial fluids into the alveoli
- Excess interstitial fluids drawn back into capillary by
- osmosis or into lymphatic vessels
-
Systemic Circuit
- Composed of vessels that lead frm the heart to all body parts (except the lungs) & back to the heart
- Includes the aorta & its branches
- Includes the sys of veins that return blood to the rt atrium
-
Characteristics of Venous Pathways
- Return blood to the heart after gas, nutrient, & waste exchange in the tissues of the body
- Vessels of the venous sys originate w/ the merging of capillaries into venules, venules into small veins, & small veins into larger ones
- Unlike arterial pathways, those of the venous sys are difficult to follow due to irregular networks & unnamed tributaries
- Larger vessels usually parallel arteries
-
Lifespan Changes
- Cholesterol deposit in the blood vessels
- Heart enlargement caused by cardiovascular disease
- Death of cardiac muscle cells
- Increase in fibrous connective tissue of the heart
- Increase in adipose tissue of the heart
- Valves may thicken or calcify
- S-A & A-V nodes and A- V bundle become more elastic & may alter the ECG
- Inc. in b.p. due to dec. diameter of blood vessels & dec. elasticity of arteries
- Decrease in resting heart rate
- Number of capillaries decreases
- Veins change less with age than do arteries
-
Lymphatic System
- Is a vast collection of cells & biochemicals that travel in lymphatic vessels & the organs & glands that produce them
- Is a network of vessels that assist in circulating fluids
- Is closely associated with the cardiovascular system
- Transports excess fluid away from the interstitial spaces
- Transports fluid to the bloodstream
- Transports fats to the bloodstream
- Helps defend the body against diseases
-
Lymphatic Pathways
- Begin as lymphatic capillaries
- Merge to form larger lymphatic vessels
- Largest lymphatic vessels unit with veins in the thorax
-
Lymphatic Capillaries
- Microscopic, closed-ended tubes
- Located in interstitial spaces
- Networks parallel networks of blood capillaries
- Walls similar to those of blood capillaries
- The fluid in the vessels is called lymph
- Special lymphatic capillaries in the lining of the sm. intestine absorb digest fats & transport them to venous circulation
-
Lymphatic Vessels
- Walls are similar to but thinner than those of veins
- Lymphatic vessels are composed of three layers
- Have semilunar valves to help prevent backflow
- Larger vessels lead to lymph nodes and then to larger lymphatic trunks
-
What are the three layers of the lymphatic vessels?
- An endothelial lining (inner)
- Smooth muscle & elastic fibers (middle)
- Connective tissue (outer)
-
Lymphatic Trunks and Collecting Ducts
- Trunks drain lymph from the lymphatic vessels
- Named for the regions they serve.such as lumbar, intestinal, intercostal, bronchomediastinal, subclavian, & jugular
- Rt lymphatic duct starts at the union of the right jugular, right subclavian, & right bronchomediastinal trunks & dumps into the subclavian vein near the junction of the rt jugular vein
- Lt lymphatic duct begins in the abdomen, passes upward through the diaphragm beside the aorta, ascends anterior to the vertebral column through the mediastinum, & empties into the lt subclavian vein near the junction of the lt jugular vein
-
Tissue and Fluid Lymph
- Lymph is essentially tissue fluid that has entered a lymphatic capillary
- Lymph formation depends on tissue fluid formation
-
Tissue Fluid Formation
- Capillary b.p. filters H20 & sm molecules frm plasma
- Fluid contains:
- Much the same composition as plasma
- Includes nutrients, gases, and hormones
- Contains water and dissolved substances
- Smaller proteins which create plasma colloid osmotic pressure
- Lacks plasma proteins due to their large size
-
Lymph Formation
- Filtration from the plasma normally exceeds reabsorption, leading to the net formation of tissue fluid
- This increases the tissue fluid hydrostatic pressure within interstitial spaces forcing fluid into lymphatic capillaries forming lymph
- This process prevents accumulation of excess tissue fluid (edema)
-
Lymph Function
- Absorption of dietary fatsDelivery of fats to the bloodstream
- Collection of small proteins filtered out of the blood capillaries
- Delivery of these small proteins to the blood stream
- Collection of excess interstitial fluids
- Delivery of excess fluids to the bloodstream
- Delivery of foreign particles, such as bacteria & viruses, to the lymph nodes
-
How much blood does the heart pump through the body each day?
7,000 liters
-
What is the amount of contractions the heart does in an average lifetime?
2.5 billion times
-
What does the pulmonary circuit do?
O2 depleated blood goes to lungs to release CO2 and gain O2
-
What does the systemic circuit do?
- O2 rich blood goes to all body cells
- Wastes collected from body cells
-
What is the size of the heart?
-
Coverings of the Heart
- Fibrous pericardium
- Visceral pericardium
- Parietal pericardium
-
Fibrous pericardium
- Outer sac
- Fibrous and tough
-
Visceral pericardium
Inner of two layers of serous membrane
-
Parietal pericardium
- Inner lining of the fibrous pericardium
- Contiguous with visceral pericardium
-
Pericardial cavity
location and funtion
- between visceral and parietal pericardia
- Contains serous fluid, reduces friction b/t membrane layers during movement
-
Layers of the Wall of the Heart
- Epicardium (outer layer)
- Myocardium
- Endocardium
-
Epicardium (outer layer of heart)
- Aka, visceral pericardium
- Protects the heart by reducing friction
- Serous membrane of connective tissue covered by epithelium
- Has nerve fibers & blood and lymph capillaries
- Has fat in deeper layers, especially near coronary
- arteries & cardiac veins
-
Myocardium (middle layer of heart)
- Thick
- Responsible for pumping action of heart
- Mostly cardiac muscle tissue
- Muscle fibers are arranged in planes separated by connective tissue &richly supplied with nerve fibers & blood & lymph capillaries
-
Endocardium (inner layer of heart)
- •Epithelium & underlying connective tissue
- Lines all heart chambers, covers valves, & is continuous w/ inner linings of blood vessels
- Contains blood vessels
- Contains specialized cardiac muscle fibers called Purkinje fibers
-
Septa
- Separate parts of the heart
- Interatrial septum separates right and left atrium
- Interventricular septum separates right and left ventricle
-
Sulci
- Grooves on surface of heart marking divisions b/t chambers of heart
- Contains major arteries & veins that supply heart tissue
- Atrioventricular sulcus encircles heart between atria & ventricles
- Interventricular sulci separate right and left ventricle
- Anterior & posterior
-
Chordae tendineae
- Strong, fibrous strings attached to cusps on ventricular side
- Originate frm papillary muscles, which contract when ventricle contracts to prevent cusps frm swinging backward into atrium during contraction
-
Anastomoses
Provide alternate routes of blood flow in case a capillary becomes blocked
-
Heart Action
- Heart actions are regulated so that atria contract (atrial
- systole) while ventricles relax (ventricular diastole); followed by ventricles contract (ventricular systole) while atria relax (atrial diastole)
-
What % of blood in the atrium flows into the ventricle based on creation of a vacuum?
30%
-
What causes heart sounds and a murmur?
- Heat sound:
- The “lubb”
- The first heart sound
- Occurs during ventricular systole
- The A-V valves are closing
- The “dupp”
- The second heart sound
- Occurs during ventricular diastole
- The pulmonary and aortic semilunar valves are closing
- Murmur: abnormal heart sound frm the cusps not completely closing
-
What are syncytia and what is their importance?
Cardiac muscle fibers form a functional syncytium, a mass of merging cells that act as a unit
-
Cardiac Conduction System
- SA Node -
- Atrial Synctium -
- Junctional Fibers -
- AV Node -
- AV bundle -
- Bundle Branches
- Purkinje fibers
- Ventricular synctium
-
Which is known as the "pacemaker"?
Sinoatrial node (SA Node)
-
What is an electrocardiogram?
Recording of electrical changes that occur in the myocardium during the cardiac cycle
-
P wave
Slow atrial depolarization triggered by a cardiac impulse frm the S-A node
-
QRS complex
- Rapid depolarization
- Walls are thick so greater change in electrical potential so stronger deflection/signal
-
T wave
Slow ventricular repolarization
-
What regulates the heart rate?
- SA node controls heart rate
- Sympathetic and parasympathetic fibers that control the heart rate
- Regulatory reflex centers that influence heart rate
- Additional factors that may influence heart rate include:
- Physical exercise
- Body temperature
- Concentration of various ions including:
- Potassium
- Calcium
-
Blood Vessels
- Arteries - carry blood away from the ventricles of the
- heart
- Arterioles - receive blood from the arteries and carry blood to the capillaries
- Capillaries - sites of exchange of substances between the blood and the body cells
- Venules -receive blood from the capillaries
- Veins - carry blood toward the atria of the heart
-
Arteries
- Thick strong wall (three layers or tunics)
- Endothelial- tunica interna
- Middle layer- tunica media
- Thickest layer of arterial wall
- Outer layer- tunica externa or adventitia
- Thin
-
Artery
Type of Wall
- Thick, strong wall with three layers
- -Endothelial lining
- -Middle layer of smooth muscle & elastic tissue
- -Outer layer of connective tissue
-
Artery
Function
Carries blood under relatively high pressure from heart to arterioles
-
Arteriole
Type of Wall
- Thinner wall than an artery but w/ 3 layers
- Smaller arterioles have:
- -endothelial linning
- -some smooth muscle tissue
- -small amt of connective tissue
-
Arteriole
Function
- Connects an artery to a capillary
- helps control the blood flow into a capillary by vasoconstricting or vasodilating
-
Capillary
Type of Wall
Single layer of squamous epithelium
-
Capillary
Function
- Provides a membrane through which nutrients, gases, & wastes are exchanged b/t the blood & tissue
- Connects an arteriole to a venule
-
Venule
Type of Wall
- Thinner wall than an arteriole
- less smooth muscle & elastic tissue
-
Venule
Function
Connects a capillary to a vein
-
Vein
Type of Wall
- Thinner wall than an artey but with smaller layers
- middle layer is poorly developed
- some have flaplike valves
-
Vein
Function
- Carries blood underrelatively low pressure from a venule to the heart
- Valves prevent a backflow of blood
- Serves as blood reservoir
-
Capillaries
- Smallest diameter blood vessels
- Semi-permeable to allow exchange of substances b/t blood & interstitial fluid
-
Capillary Exchanges
- Methods of exchange:
- Diffusion
- Most important
- O2, nutrients, CO2, wastes
- Lipid solubility determines if diffusion is directly through the cell wall or through pores
- Plasma proteins trapped in capillary b/c they are not lipid soluble & too large to pass through pores
- Filtration
- Hydrostatic pressure frm ventricular contractions forces molecules through membranes
- Force reduced w/ greater distance frm heart due to friction
- Osmosis
- Due to impermeable solute on one side of membrane
- Plasma proteins
-
Vessels associated with the heart
- Superior vena cava
- Inferior vena cava
- Pulmonary trunk
- Left and right pulmonary arteries
- Left and right pulmonary veins
- Aorta/Aortic arch
- Left and right coronary arteries
-
Branches of the aorta
- Brachiocephalic
- Common carotid arteries
- Subclavian arteries
- Celiac arteries
- Phrenic arteries
- Mesenteric arteries
-
Arteries of the limbs
- Radial arteries
- Femoral arteries
-
Veins
- Brachiocephalic veins
- Internal jugular veins
- External jugular veins
- Subclavian veins
- Hepatic portal vein
- Mesenteric veins
-
Veins of the limbs
- Radial arteries
- Femoral arteries
-
The lymphatic system
- Vast collection of cells and biochemicals that travel in lymphatic vessels and the organs and glands that produce them
- Network of vessels that assist in circulating fluids
- Closely associated with the cardiovascular system
- Transports excess fluid away from the interstitial spaces
- Transports fluid to the bloodstream
- Transports fats to the bloodstream
- Helps defend the body against diseases
-
Basic Lymphatic pathway
- Begin Lymphatic capillaries
- Merge to form larger lymphatic vessels
- Largest lymphatic vessels unite w/ veins in the thorax
-
What is lymph?
Fluid in the lymph vessels
-
Lymph Movement
- Hydrostatic pressure of tissue fluid drives the lymph into the lymphatic capillaries
- Epithelial cells of walls of lymphatic capillaries overlap but are not attached to each other creating flap-like valves
- Valves are pushed open when fluid pressure is greater in the interstitial spaces than in the lymph vessel & close when the pressure is greater inside the vessel
- Epithelial cells of capillary wall are attached to surrounding connective tissue cell by thin protein filaments
-
Lymph Nodes
- Blood vessels and nerves enter through the concave region called the hilum
- Afferent lymph vessels enter nodes separately and at various locations on the node’s convex surface
- Efferent vessels leave the node from the hilum
- A capsule of connective tissue with numerous fibers encloses the node and subdivides it into compartments called lymph nodules
- Germinal centers within nodules contain actively
- dividing lymphocytes and monocytes
- Lymph nodules occur singly and in groups associated w/ mucous membranes of the respiratory & digestive tracts
- Lymph sinuses are spaces w/in the nodes that provide a complex network of chambers & channels through
- which the lymph circulates
-
Locations of Lymph Nodes
- Lymph nodes are found in groups or chains along the paths of the larger lymphatic vessels throughout the body, including the:
- Cervical region
- Axillary region
- Supratrochlear region
- Inguinal region
- Pelvic cavity
- Abdominal cavity
- Thoracic cavity
-
Functions of Lymph Nodes
- Lymph nodes have two primary functions:
- Filter potentially harmful particles from the lymph before returning it to the blood stream
- Provide immune surveillance using macrophages & lymphocytes
- Attack viruses, bacteria, & other parasites that reach the lymph nodes
- Macrophages phagocytize foreign substances, damaged cells, & cellular debris
- Along with the red bone marrow, the lymph nodes are centers for lymphocyte production
-
Two other lymphatic organs w/ functions similar to those of the lymph nodes
Thymus and Spleen
-
Thymus
- Larger in infancy and during puberty
- Small in an adult
- Replaced by fat and connective tissue in the elderly
- Subdivided into lobules by connective tissue extending inward frm the surface
- Site of T lymphocyte (or T cell) production
- Secretes protein hormones called thymosins that induce maturation of T cells after they migrate to other lymphatic tissues
-
Spleen
- largest lymphatic organ
- Located in the upper left abdominal quadrant
- Has sinuses filled with blood (the major difference from large lymph nodes)
- Contains two tissue types:
- White pulp
- -In tiny islands throughout spleen
- -Contains lymphocytes
- Red pulp
- -Rest of lobules
- -Contains red blood cells, lymphocytes & macrophages
-
Mechanical Barriers
- The skin & mucous membranes create mechanical barriers
- Considered the first line of defense (all other non-specific defenses are part of the second line of defense)
-
Second Line of Defense
- Chemical barriers
- Natural killer cells
- Inflammation
- Phagocytosis
- Fever
-
Chemical Barriers
- Enzymes in body fluids provide a chemical barrier to pathogens, and they may include:
- Interferons are horomone-like peptides and stimulate phagocytosis
- Defensins are peptides produced by neutrophils & other granulocytes. They cripple microbes.
- Collectins are proteins w/ broad protection against bacteria, yeast & some viruses
- Complement is a group of proteins in plasma & other body fluids that stimulate inflammation, attract phagocytes & enhance phagocytosis
-
Natural Killer (NK) Cells
- NK cells are a small population of lymphocytes defending against viruses & cancer by secreting cytolytic substances called perforins that destroy the infected cell
- NK may also enhance inflammation
-
Inflammation
Inflammation produces local redness, swelling, heat and pain
-
Phagocytosis
- Removes foreign particles from the lymph
- In the blood vessels and in the tissues of the spleen, liver or bone marrow
- The most active phagocytic cells are neutrophils and monocytes
- Chemicals attract these phagocytic cells to the injury and this is called chemotaxis
-
Fever
Begins when a viral or bacterial infection stimulates lymphocytes to proliferate, producing cells that secrete a substance called interleukin-1 (IL-1)
-
Adaptive (Specific) Defenses or Immunity
- Third line of defense and known as immunity
- It is resistance to particular pathogens or to their toxins or metabolic by-products
- It is based on the ability to distinguish molecules that are part of the body (“self” from “non-self”)
- Antigens are molecules that can elicit an immune response
-
Antigens
- Antigens may be:
- Proteins
- Polysaccharides
- Glycoproteins
- Glycolipids
- The most effective antigens are large and complex
- Haptens are small molecules that are not antigenic by themselves, but when they combine with a large molecule can stimulate an immune response
-
T Cells and the Cellular Immune Response
- A lymphocyte must be activated before it can respond to an antigen
- T cell activation requires antigen-presenting cell (accessory cell) and may include macrophages, B cells and several other types of cells
- Requires major histocompatibility complex (MHC) or human leukocyte antigens (HLA) to recognize “non-self”
- T cells can synthesize and secrete polypeptides called
- cytokines
- Types of specialized T cells include:
- -Helper T cells
- -Cytotoxic T cells
- -Memory T cells
-
B Cells and the Humoral Immune Response
- B cells can be activated when an antigen fits the shape of its receptor
- Most of the time B cell activation requires T cells
- T cells release cytokines that stimulate B cells
- Some B cells may become memory B cells while others differentiate into plasma cells and produce and secrete large globular proteins called antibodies or immunoglobulins
-
Allergic Reactions
- Type I
- -Immediate-reaction allergy
- -Occurs minutes after contact with allergen
- -Symptoms include hives, hay fever, asthma, eczema, gastric disturbances, and anaphylactic shock
- Type II
- -Antibody-dependent cytotoxic reaction
- -Takes 1-3 hours to develop
- -Transfusion reaction
- Type III
- -Immune-complex reaction
- -Takes 1-3 hours to develop
- -Antibody complexes cannot be cleared from the body
- -Damage of body tissues
- Type IV
- -Delayed-reaction allergy
- -Results from repeated exposure to allergen
- -Eruptions and inflammation of the skin
- -Takes about 48 hours to occur
-
Transplantation and Tissue Rejection
- Successfully transplanted tissues and organs:
- -Cornea
- -Kidney
- -Liver
- -Pancreas
- -Heart
- -Bone marrow
- -Skin
- When the donor’s tissues are recognized as foreign there is a tissue rejection reaction
- -Resembles the cellular immune response against antigens
- -Important to match MHC antigens
- -Immunosuppressive drugs used to prevent rejection
-
Transplant Types
- Isograft
- Donor: Identical twin
- EX: Bone marrow transplant from a healthy twin to a twin who has leukemia
- Autograft
- Donor: Self
- Ex: Skin graft from one part of the body to replace burned skin
- Allograft
- Donor: Same species
- Ex: Kidney transplant from a relative or close matched donor
- Xenograft
- Donor: Different species
- Ex: Heart valves from a pig
|
|