Circulatory and Respiratory Systems. The Circulatory System.
The Circulatory System
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The Circulatory System Unit 4
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Transcript of The Circulatory System
The Circulatory System
Unit 4
I. Blood
A. Terms1. Agglutination:
the process by which cells stick together to form clumps
2. Antibody: a protein in the plasma produced by a type of activated WBC. Once produced, it binds to an antigen to neutralize it
3. Antigen: a protein on the plasma membrane of RBC that stimulate certain WBC to produce antibodies
4. Embolus: a substance transported by the blood. Examples: blood clots, air bubbles
5. Hemostasis: the stoppage of
bleeding6. Thrombus:
a blood clot that has formed in a blood vessel
B. Functions
Maintenance of homeostasis by:
1. Transportation of respiratory gases, nutrients, metabolic wastes and hormones
2. Protection against harmful microorganisms and toxins, and fluid loss
3. Regulation of acid-base balance and body temperature
C. PropertiesColor: red due to hemoglobinVolume: males 5 – 6 liters; females 4 – 5 litersViscosity: 5 times greater than waterpH: between 7.35 and 7.45
D. Components:
All of the following components of blood are produced in red bone marrow
1. Plasma: the liquid portion of blood. It is mostly water with some solutes such as plasma proteins (albumins, globulins & fibrinogen)
2. Red Blood Cells: RBCs: erythrocytes
Biconcave so that they can carry a maximum amount of hemoglobinHgb binds to O2 which is delivered to the cells andCarries away CO2
The production of RBCs is regulated by a hormone (erythropoietin) secreted by cells in the kidneys
3. White Blood Cells: WBCsLeukocytes
Protects the body from diseaseLymphocytes: produce antibodiesBasophils: cause inflammation
Neutrophils and monocytes: are phagocyticEosinophils: battle allergens through phagocytosis
4. Thrombocytes/Platelets
Plays an important role in blood clotting
Components 2, 3 and 4 are
formed elements
E. HemostasisThe stoppage of bleeding
1. Blood vessel spasm: the smooth muscle tissue in the walls of the blood vessels contractResulting in the temporary closure of the opening
2. Platelet plug formation
When platelets arrive at the site of blood vessel breakage, theyIncrease in size and become irregular in shapeAnd their surface becomes sticky
At the site of the break in the blood vessel, platelets stick to one another and to collagen fibers in the blood vesselForming a “clump” that can seal a small break
3. Coagulation
The most effective and complex of the blood clotting mechanismsIt involves a series of events that results in the formation of a network that traps the formed elements creating a barrier over the site
The process of coagulation takes approximately 2 to 8 minutes to completeA lack of any of the factors necessary can lead to an inability of the blood to clot
Dietary deficiencies (especially in vitamin K), liver disease or hemophilia can result in an inability to form clots
In some cases, a blood clot may form when it is not needed. This can happen if the inner wall of the blood vessel is rough or if it contains an accumulation of fatty deposits (as seen in atherosclerosis)
The blood clot that forms is called a thrombus which can cause death if it blocks the flow of blood to a vital organ
If the blood clot detaches and moves, it is called an embolus. It can be fatal if it lodges in a blood vessel feeding into a vital organ
F. Hemopoiesis
The process of blood cell formation in the red bone marrowAll of the formed elements originate from a single population of cells
called stem cells These cells differentiate to form the different cell lines, each of which lead to a particular type of formed element
G. Blood Groups
The blood groups are named based upon the antigens found in their blood.There are only two types of antigens: A and B
There are antibodies in the plasma that form early in life and react with the antigens not contained in blood
Blood type
antigen antibody
A A Anti-B
B B Anti-A
AB A & B Neither
O NONE Anti-A & Anti-B
A blood transfusion involves the introduction of blood from an alternate source. If the two blood types are not compatible, agglutination occurs creating a transfusion reaction
In a transfusion reaction, RBCs are destroyed, hgb and bilirubin enter the body eventually causing kidney failure and death
Compatibility
Blood type
Donate to
Receive from
A A & AB A & O
B B & AB B & O
AB AB ALL
O ALL O
Rh system
It was originally identified in, and named after, the Rhesus monkeyRh antigens are found on the RBC membranes
The presence of the Rh antigen is indicated by having a positive blood typeThe absence of the Rh antigen is indicated by a negative blood type
The antibodies (anti-Rh) for the antigens are not formed until the Rh-negative person becomes exposed to the antigen
Sensitization can occur through blood transfusions or through pregnancy.
During a first pregnancy, an Rh-negative female carrying an Rh-positive fetus, presents no major health risk.During delivery, the placental membrane may tear allowing the two bloods to mix
This exposure may sensitize the mother’s immune system causing her to create anti-Rh antibodies
In subsequent Rh-positive pregnancies, the antibodies will cross the placenta and cause agglutination with the fetal RBCs
This causes a condition called hemolytic disease or erythroblastosis fetalisBrain damage or death may result unless blood transfusions are performed before birth
If the situation is detected with the first pregnancy, sensitization can be avoided through treatment with a substance called RhoGAM
II. The Cardiovascular System
A. Structure of the Heart1. Pericardium
The outer covering of the heart
Layers of the pericardium:Parietal Pericardium: tough outermost layerVisceral Pericardium: innermost, thin layerPericardial Cavity: the space in between
2. Heart Wall
Consists of 3 layers:Epicardium: thin, outer membrane
Myocardium: middle layer forming the bulk of the heart; the primary functional tissueEndocardium: thin, inner layer
3. Heart Chambers
2 Atria:Superior chambersThin walledReceiving chambers for incoming bloodSeparated by interatrial septum
2 VentriclesInferior chambersThick walledServe as pumps for pushing blood out of the heartSeparated by interventricular septum
http://www.youtube.com/watch?v=P_d0ykpzQgY
4. Heart Valves
Atrioventricular (AV) valvesAllow one-way flow of blood from the atria to the ventricles
They close during ventricular contractionTricuspid valve:Between the right atrium and right ventricleBicuspid or Mitral valve:Between the left atrium and left ventricle
Semilunar (SL) Valves
Allow the one-way flow of blood from the ventricles to the pulmonary trunk and aortaThey close during ventricular relaxation
Pulmonary valve:Between the right ventricle and the pulmonary trunkAortic valve:Between the left ventricle and the aorta
5. Blood Flow
Through the heart:Right atrium through the tricuspid valve toright ventricle
through the pulmonary valveto the lungs through the pulmonary arteriesblood re-enters the heart through the pulmonary veins intothe left atrium
through the mitral valve intothe left ventriclethrough the aortic valve intothe aorta
To the Heart
Right and left coronary arteries branch from the base of the aorta to supply the heart wall.
B. Physiology
1. Cardiac cycleContraction of both atriaContraction of both ventricles
Pressure changes following the contraction/relaxation cyclesprovides the force necessary to move the blood
2. Heart Sounds
LUB: AV valves closingDUB: SL valves closing
3. Regulation of heart activity
The heart does not require external stimulation for contractions to occurThere is an intrinsic regulating system within the heart wall
Specific pace-setting cells in heart muscle send electrical signals to adjacent cellsEvery cardiac muscle cell is initiated by these pace-setting cells
The main site of pace-setters is in the sinoatrial node.Because of this, the SA node is also known as the pacemaker as it initiates each cardiac cycle.
C. Blood Vessels
Tubes that carry bloodIncluding:arteries, arteriolescapillariesveins, venules
1. Arteries and Arterioles
Carry blood away from the heartMiddle layer has smooth muscles and elastic fibers
Because of this, arteries are able to contractand “flex” with the flow of blood
As arteries extend from the heart, they become progressively smallerbecoming arterioleswhich are much thinner Arterioles branch into tiny capillaries
2. Capillaries
The smallest vessels in the bodyThin-walled tubes that permit the exchange of materials between the blood and interstitial fluid
The capillary wall is composed of a single layer of flattened cellsCapillaries are so small that only one RBC can pass through at a time
Capillaries have pores that allow fluid from the bloodstream to leak through to the areas surrounding the cellsThis is interstitial fluid
3. Venules and Veins
Three-layered tubes that carry blood toward the heartCapillaries join to venules which enlarge to form veins
The walls of veins are much thinner than arteriesVeins contain less smooth muscle and elastic fibers than arteries
Because of this, veins are much less elastic and do not contract and flex as easily as arteries doThe large size of veins allows them to hold large amounts of blood
~65% of the total blood supply is within the veins at any given timeEven still…they are usually only partially filled and are slightly collapsed
At other times, veins may fill completely causing the wall to become distendedThis change in blood volume causes a corresponding change in blood pressure
Because of this, when the flow of blood reaches the veins from the venules, the pressure may not be high enough to push the blood upwards towards the heart
To maintain a one-way direction of blood movement,
1. Veins contain valves similar to the semilunar valves of the heart
2. Respiratory and skeletal muscles “squeeze” veins preventing the backflow of blood
D. Circulatory Pathways
I. Pulmonary circulationThe pathway between the heart and the lungsThe purpose of this pathway is for the oxygenation of blood
Blood lower in oxygen and higher in CO2 leaves the heart from:
1. the right ventricle2. through the pulmonary
semilunar valve3. to the pulmonary trunk
4. which branches into the right and left pulmonary arteries
5. Which branch into smaller arteries,
6. then into arterioles, 7. then into pulmonary
capillaries
8. which form networks that surround the air sacs of the lungs
9. Gas exchange occurs between the pulmonary capillaries and the air sacs…O2 is loaded onto the RBCs and CO2 is released
10.pulmonary capillaries drain into venules which unite to form the two pulmonary veins exiting each lung
11. the four pulmonary veins enter the left atrium
II. Systemic Circulation
The vessels that extend from the left ventricle through the body to the right atrium of the heartproviding fresh blood to all body tissues (except the lungs)
Bringing:oxygenated bloodnutrients from the digestive tracthormones from endocrine glandsenzymes and proteinsWBCs to fight infectionto the tissues
Taking:Carbon dioxidenonprotein nitrogenous wasteaway from the tissues
1. Blood leaves the left ventricle
2. through the aortic semilunar valve
3. into the aorta4. through the thoracic
and abdominal cavities5. branching off
throughout the body
6. subdividing into arterioles and capillaries
7. joining together into venules, then veins
8. Draining into the superior and inferior vena cava
9. Which enter into the right atrium
