circulatory system
consists of the heart, blood vessels, and blood
cardiovascular system
consists of only the heart and blood vessels
hematology
study of blood
functions of the circulatory system
1. transport 2. protection 3. regulation
plasma
a clear, light yellow fluid constituting a little over half of the blood volume
formed elements
cells and cell fragments
serum
remaining fluid once the blood clots and solids are removed from blood
albumin
smallest, most abundant plasma protein; responsible for blood's viscosity and osmolarity; formed in liver
globulins
antibodies; provide immune system defenses; come in alpha, beta and gamma; produced by plasma cells which descend from B lymphocytes
fibrinogen
precursor of fibrin threads that help form blood clots; formed in liver
nitrogenous wastes
toxic end products of catabolism
viscosity
the resistance of a fluid to flow
osmolarity
total molarity of dissolved particles that cannot pass through the bood vessel walls
hemopoiesis
production of blood
hemopoietic tissue
tissues that produce blood
myeloid hemopoiesis
production of blood in bone marrow
lymphatic hemopoiesis
production of blood in lymphatic organs
hemopoietic stem cell (HSC)
type of stem cells that create formed elements
colony-forming units (CFUs)
more specialized stem cells for formed elements
Erythrocytes
red blood cells (RBCs); two fuctions 1. pick up oxygen from the lungs and delivers it to other tissues and 2. pick up carbon dioxide from the tissues and unload it in the lungs
How long do RBCs last?
120 days
Erythropoiesis
produces 2.5 million RBCs/second from stem cells (hemocytoblasts) in bone marrow; need iron, vitamin B12, folic acid, vitamin C and copper; HSC->erythrocyte CFU->erythroblast->reticulocyte->erythrocyte
Contents of RBCs
1. hemoglobin: cytoplasm consists mainly of this; aids in oxygen transport
2. glycolipids: found on the plasma membrane; determines blood type
3. CAH: in the cytoplasm; catalyzes the reaction CO2+ H20=H2CO3
hemoglobin
consists of 4 protein chains (globins) -> 2 alpha & 2 beta + 4 hemes (binds oxygen to Fe++) in adult hemoglobin (HbA). In HbA2 2 alpha + 2 delta chains. In fetal hemoglobin (HbF) 2 alpha + 2 gamma chains.
polycythemia
excess of RBCs; primary polycythemia is due to cancer of erythropoietic cell line in the red bone marrow
RBC count as high as 11 million/uL hematocrit of 80%;
secondary polycythemia from dehydration, emphysema, high altitude, or physical conditioning. RBC
pernicious anemia
inadequate vitamin B12 from poor nutrition or lack of intrinsic factor from glands of the stomach
iron-deficiency anemia
lack of iron in blood
aplastic anemia
complete cessastion of erythropoiesis or hemoglobin synthesis
hemorrhagic anemia
blood loss
hemolytic anemia
RBC destruction
anemia effects
1. tissue hypoxia and necrosis (short of breath & lethargic)
2. low blood osmolarity (tissue edema)
3. low blood viscosity (heart races & pressure drops)
sickle cell disease
hereditary Hb defect of African Americans; HbS turns to gel in low oxygen concentrations causing cell elongation and sickle shape; cell stickiness causes agglutination and blocked vessels, intense pain, kidney and heart failure, paralysis, and stroke; enl
RBC antigens
called agglutinogens A & B; proteins, glycoproteins and glycolipids on red blood cell
Plasma antibodies
called agglutinins anti-A & -B; gamma globulins in blood plasma that recognize (stick to) foreign agglutinogens on RBCs; responsible for RBC agglutination in mismatched blood transfusions; appear 2-8 months after birth
Mismatched transfusion reaction
Agglutinated RBCs block blood vessels & rupture; free Hb can block kidney tubules & cause death
Rh factor
D antigens; not normally present in blood
hemolytic disease of newborn
Rh- pregnant woman carrying an Rh+ fetus or blood transfusion of Rh+ blood; no problems result with either the first transfusion or the first pregnancy, abortion or miscarriage; given RhoGAM or Gamulin Rh Ig during 2nd pregnancy so antibodies don't form;
Leukocytes
WBCs; protect against infections and other diseases
neutrophils
granulocytes; most abundant; destroys bacteria; rises with bacteria infections
eosinophils
granulocytes; secrete chemicals that weaken or destroy relatively large parasites and phagocytize and dispose of inflammatory chemicals, antigen-antibody complexes, and allergens; rises with allergies, parasitic infections, collagen diseases, and disease
basophils
granulocytes; rarest; secretes: 1. histamine: vasodilator so blood can get to tissues more quickly and 2. heparin: anticoagulant that inhibits blood clotting and promotes other WBCs to go to the area
Lymphocytes
agranulocytes; abundant after neutrophils; immune fuctions
monocytes
agranulocytes; largest of WBCs; count rises in inflammation and viral infections; transform into macrophages
Leucopoiesis
the production of white blood cells
leukopenia
deficiency of WBCs; below 5,000 WBCs/uL; indicates lead, arsenic and mercury poisoning, radiation sicknesses, and infections like measles, mumps, polio etc.
leukocytosis
high WBC count; above 10,000 WBCs/uL; indicates infection, allergy, or other diseases
leukemia
cancer of hemopoietic tissues that usually produces a high number of circulating leukocytes and their precursors
thrombopoiesis
production of platelets
hemostasis
cessation of bleeding
myeloid leukemia
uncontrolled granulocyte production
lymphoid leukemia
uncontrolled lymphocyte or monocyte production
acute leukemia
appears suddenly, progresses rapidly, and causes death
chronic leukemia
develops slowly, may go undetected for months
Fate of blood clots
1. Clot retraction occurs within 30 minutes (pseudopods of platelets contract condensing the clot)
2. Platelet-derived growth factor is secreted by platelets & endothelial cells which stimulates fibroblasts and smooth muscle cells to multiply and repair d
hemophilia
definiciency in any clotting factor that can shut down the coagulation cascade
lack of factor 8 causes A 83%; lack of 9 causes B 15%; lack of 11 causes C
Thrombosis
the abnormal clotting of clood in an unbroken vessel; most likely to occur in leg veins of inactive people
Embolism
unwanted clot traveling in a vessel; can travel into lungs causing a pulmonary embolism->death from hypoxia
hematoma
masses of clotted blood in the tissues
blood components
plasma-55%
leukeocytes and platelets-<1%
RBCs-45%
Hematocrit = 37-52%
Functions of blood
1. Transports O2, CO2, nutrients, wastes, hormones, and stem cells
2. Protection-Inflammation, limit spread of infection, destroy microorganisms and cancer cells, neutralize toxins, and initiate clotting
3. Regulation-Fluid balance, stabilizes pH of ECF,
pulmonary circuit
Superior vena cava->right atrium->tricuspid valve->right ventricle->pulmonary vein->lungs->pulmonary artery
carries deoxygenated blood to the lungs and brings it back to the heart
systemic circuit
left atrium->bicuspid valve and mitral valve->left ventricle->aorta->blood to the rest of the body
pumps blood to every organ of the body
myocardium
between epicardium and endocardium; thickest layer and performs the work of the heart; composed of spontaneously contracting cardiac muscle fibers
atria
2 upper chambers; thin walled; Receive blood from veins
Send blood to ventricles
ventricles
Thick walled; Receive blood from atria; Pump blood out through arteries
septum
wall that divides the heart into right and left halves
valves
prevents backflow of blood and keeps blood moving in one direction; between chambers and at junctions of arteries and chambers
Left coronary artery (LCA)
travels through coronary sulcus under the left auricle and divides into two branches: 1. Anterior Interventricular: supplies blood to ventricles, anterior 2/3rds of the interventricular septum AND 2. circumflex branch: supplies blood to LA and posterior w
Right coronary artery (RCA)
supplies the RA and sinoatrial node, continues along the coronary sulcus under the right auricle and gives off two branches: 1. right marginal branch: supplies lateral aspect of the RA and RV AND 2. posterior interventricular branch: supplies posterior po
Great cardiac vein
collects blood from the anterior aspect of the heart; carries blood from the apex toward the coronary sulcus and empties into the coronary sinus
Posterior interventricular (middle cardiac) vein
collects blood from the posterior aspect of the heart; carries blood from the apex toward the coronary sulcus and empties into the coronary sinus
left marginal vein
travels from the apex and into the coronary sinus
coronary sinus
a large transverse vein in the coronary sulcus on the posterior side of the heart; empties blood into RA
blood supply to myocardium
LCA->Ant. interventricular branch and circumflex branch (leads to left marginal branch)
RCA->right marginal branch and post. interventricular branch
angina
sense of heaviness or pain the chest resulting from temporary or reversible deficiency of blood flow to the cardiac muscle
heart attack
myocardial infarction; sudden death of a patch of myocardium resulting from long-term obstruction of the coronary circulation
nerve supply
sympathetic pathway to the heart originates in the lower cervical to upper thoracic segments of the spinal cord
parasympathic pathway begins with the nuclei of the vagus nerves in the medulla
both go to the cardiac plexus and continue via cardiac nerves
pacemaker
SA node triggers normal cardiac rhythm
AV node triggers slower heart rate when SA node is damaged
buncle of His
AV bundle; pathway by which signals leave the AV node
purkinje fibers
nervelike processes that arise from the lower end of the bundle branches and turn upward to spread throughout the ventricular myocardium; distribute the electrical excitation to cardiocytes of the ventricles
How are pulmonary vein and artery different from the rest of the arteries and veins?
Pulmonary artery carries deoxygenated blood from right ventricle to lungs and pulmonary vein brings oxygenated blood from lungs to the left atrium
EKG
a test that measures the electrical activity of the heartbeat or one cardiac cycle
pacemaker physiology
SA node doesn't have a stable RMP; after depolarization the SA node produces one heartbeat
cardiac arrhythmias
any abnormal cardiac rhythm
ventricular fibrillation
serious arrhythmia caused by electrical signals arriving at different regions of the myocardium at widely different times
atrial flutter
occurs when ectopic foci in the atria set of extra contractions and the atria bears 200 to 400 times per minute
premature ventricular contractions
occur singly or in bursts as a result of early firing of ectopic focus; usually caused by heart irritation due to stimulants, emotional stress, or lack of sleep
heart sounds
S1 lubb-due to closure of the atrioventricular valves (mitral and tricuspid)
S2 dupp- to closure of the aortic valve and pulmonary valve
heart murmur
regurgitation of blood through the incompetent valves; caused by valvular insufficiency due to scar tissue or stiffened cusps or hereditary
cardiac output
the amount ejected by ventricle in 1 minute; heart rate x stroke volume; About 4 to 6 L/min at rest; Vigorous exercise increases CO to 21 L/min for a fit person and up to 35 L/min for a world-class athlete
How to measure heart beat
Usually it is calculated as number of contractions of heart (heart beats)in one minute and expressed as bpm; The pulse is the most straightforward way of measuring the heart rate
diastole
period of time when the heart relaxes after contraction
systole
contraction of the heart
exercise and cardiac output
proprioceptors in the muscles and joints transmit signals to cardiac centers, signfying that the muscles are active and will quickly need an increased blood flow, which makes the heart bear faster; by exercising your ventricles hypertrophy which allows th
coronary artery disease
constriction of the coronary arteries usually resulting from the accumulation of lipid deposits that degrade the arterial wall and obstruct the lumen
1. pathogenesis- hypertension, diabetes, etc, damages the arterial lining; monocytes penetrate the tissue
arteries
Receive blood from ventricles
Take blood away from the heart
Usually carry oxygenated blood
Thickest vessel walls
Withstand greater blood pressure
Are very elastic
Connect to capillaries
veins
Transport blood away from capillaries
Carry blood toward heart
Take blood to atria
Have valves
Thinner vessel walls with less smooth muscles
than arteries
Can stretch a great deal
Have larger diameters
Usually carry de-oxygenated blood
capillaries
Smallest of blood vessels
Only one cell thick (epithelial cell)
Connect arteries to veins
Bring oxygen and nutrients to cells
Removes CO2, urea, and other wastes from cells
Where blood is under low pressure and moving slowly
Continuous capillaries
occur in most tissues
Endothelial cells have tight junctions forming a continuous tube with intercellular clefts
Allow passage of solutes such as glucose
Fenestrated capillaries
in the kidneys, small intestine
Organs that require rapid absorption or filtration
Endothelial cells riddled with holes called filtration pores (fenestrations)
Spanned by very thin glycoprotein layer
Allows passage of only small molecules
Sinusoids (discontinuous capillaries)
in the liver, bone marrow, spleen
Irregular blood-filled spaces with large fenestrations
Allow proteins (albumin), clotting factors, and new blood cells to enter the circulation
aneurysm
a weak point in an artery or in the heart wall; forms a thin-walled, bulding sac that pulsates with each beat of the heart and may eventually rupture
perfusion of a capillary bed
when precapillary sphincters are open the capillaries are well perfused in blood and engage in exchanges with tissue fluid; when they are closed the blood bypasses the capillaries
Venous valves
infoldings of the tunica interna that meet in the middle of the lumen; in many medium veins, especially in the limbs
varicose veins
pulling of the cusps of the venous valves farther apart until the valves become incapable of sealing the vessel and preventing the backflow of blood causing walls to become weak; caused by obesity and standing on your feet for long periods of time
blood pressure
the force exerted by circulating blood on the walls of blood vessels; Normal value, young adult: 120/75 mm Hg
hypertension
high blood pressure; Chronic is resting BP > 140/90
Consequences: Can weaken small arteries and cause aneurysms
hypotension
low blood pressure; Caused by blood loss, dehydration, anemia
How to measure BP
Blood pressure is most commonly measured using a sphygmomanometer (blood pressure cuff)
It uses the height of a column of mercury to reflect the circulating pressure
Factors that regulate BP
cardiac output, blood volume, and peripheral resistance (determined by viscosity, vessel length and radius)
edema
the accumulation of excess fluid in a tissue; Occurs when fluid filters into a tissue faster than it is absorbed
Stroke
cerebrovascular accident (CVA); sudden death (infarction) of brain tissue causes by ischemia (can be produced by atherosclerosis, thrombosis, or a ruptured aneurysm
Functions of the lymphatic system
1. fluid recover
2. immunity
3. lipid absorption
lymph
a usually clear, colorless fluid, similar to blood plasma but low in protein
lymphoid tissue
Specialized connective tissue with vast quantities of lymphocytes
lymph vessels
system of vessels similar to blood vessels that lymph flows through
lymphatic capillaries
penetrate nearly every tissue of the body but are absent from CNS, cartilage, bone, cornea, and bone marrow; similar to blood capillaries, but closed at one end
collecting vessels
formed by converging lymphatic capillaries; often travel alongside arteries and veins; empty into lymph nodes
lymph nodes
where bacteria are phagocytized and immune cells monitor the lymph for foreign antigens and site of T and B cell activation
lymphatic trunks
made by converging collecting vessels; each drains a major portion of the body; 1. jugular, 2. subclavian, 3. bronchomediastinal, 4. intercostal, 5. intestinal and 6. lumbar
collecting ducts
made by converging lymphatic trunks; right lymphatic duct-in the right throacic cavity; thoracic duct-just below diaphragm
lymph organs
red bone marrow, thymus, lymph nodes, tonsils, and spleen
red bone marrow
where B lymphocytes are able to recognize and respond to antigens
thymus
houses developing lymphocytes and secretes hormones that regulate their later activity; located between the sternum and aortic arch
tonsils
patches of lyphatic tissue located at the entrance of the pharynx; guards against ingested and inhaled pathogens
spleen
inferior to diaphragm and posterolateral to the stomach; Removes blood-borne antigens (white pulp), Removes & destroys aged or defective blood cells (red pulp) and Stores platelets
3 levels of protection
1. external barriers (skin and mucous membranes)
2. non-specific defense mechanisms against pathogens that break through the 1st lever (leukocytes, macrophages, antimicrobial proteins, immune surveillance, inflammation and fever)
3. immune system-defeats
antigen
any large molecule capable of binding to an antibody and triggering an immune response
pathogen
virsuses, bacteria, fungi, and other microbes that cause disease
tolerance
Non-reactivity of the immune system, usually refers to "self" but may include foreign tissue in organ transplants
autoimmunity
A failure of tolerance, the immune system reacts to self
chemokine
Molecules released by pathogens and infected tissues to attract cells of the immune system
cytokines
Signaling molecules released by one cell to cause a response in another. Signaling is extremely important in our immune response
innate immunity
Immunity we are born with. Dendritic cells, macrophages, B cells etc
adaptive immunity
Protection that arises by an immune response, including humoral immunity producing antibodies and cellular immunity
Immune cells development
pluripotent stem cell->lymphoid stem cell
in bone marrow LSC turn into Natural killer cells or B cells
otherwise they migrate to thymus and turn into mature T cells or production and differentiation of T cells
complement system
Inflammation
Immune clearance
Phagocytosis
Cytolysis
Interferons
secreted by certain cells infected by viruses; Alert neighboring cells and protect them from becoming infected; Activate NK cells and macrophages
How is secondary immune response different from the primary response?
...
cell mediated immunity cells
1. Cytotoxic T cells-effectors of cellular immunity that carry out the attack on foreign cells
2. Helper T cells-promote the action of Tc cells as well as playing key roles in humoral immunity and nonspecific resistance
3. Regulatory T cells-limit the imm
humoral immunity cells
1. B cells-
2. antibodies
3. memory B cells
immunoglobulins (Igs)
1. IgA-monomer in plasma; dimer in mucus, saliva, tears, milk, and intestinal secretions; Prevents pathogen adherence to epithelia and penetrating underlying tissues
2. IgD-monomer; B cell transmembrane antigen receptor; Thought to function in B cell acti
antigen presenting cells
when it encounters and processes an antigen, it typically migrates to the nearest lymph node and displays it to the T cells which go out and look for the cells
MHC-I
proteins that occur on every nucleated cell of the body; they pick up small peptides in the cytoplasm and display them once they are installed in the membrane; if peptides are normal self-antigens they don't elicit a T cell response; if they are not norma
MHC-II
proteins that occur only in APCs and display only foreign antigens; Th cells respond to these
immune surveillance
phenomenon in which natural killer cells continually patrol the body "on the lookout" for pathogens or diseased host cells
vaccine
consists of either dead or weaked pathogens that can stimulate an immune response but cause little or no discomfort or disease
attack by T cells
Th cells recognize pathogens and secrete interleukinds that attact neutrophils, NK cells, and macrophages and stimulate T and B cell mitosis and maturation
Tc cells directly attack and kill other cells
attack by B cells
B cells clone; plasma cells secrete antibody and makes antigens harmless
hypersensitivity
an excessive immune reaction against antigens that most people tolerate
1. Type I (acute)-most common allergies
2. Type II (antibody dependent cytotoxic)-IgG or IgM attacks antigens bound to cell surfaces which leads to lysis or opsonization of target cel
causes of autoimmunity
1. cross-reactivity: foreign antigen has similar structure to our own cells and some antibodies attack our own cells
2. abnormal exposure to self-antigens to the blood (like in blood-testis barrier)
3. change in the structure of self-antigens-viruses and
severe combines immunodeficiency disease (SCID)
group of disorders caused by recessive alleles that result in a scarcity of absense of both T and B cells
AIDS
Signs and symptoms
Early symptoms: flulike symptoms of chills and fever
Progresses to night sweats, fatigue, headache, extreme weight loss, lymphadenitis
Normal TH count is 600 to 1,200 cells/uL of blood, but in AIDS it is less than 200 cells/uL
Person su
anaphylaxis
immediate and severe allergy happens when an allergen goes into the blood stream (like medication or venom)
perforins
released by NK cells; polymerize in a ring and create a hole in its plasma membrane
costimulation
helps to ensure that immune system doesn't launch an attack in the absence of an enemy
effector
a molecule, cell or organ that carries out a response to a stimulus
primary response
the immune reaction when a person is exposed to a particular antigen for the first time
secondary response
anamnestic response; quick response when a person is reexposed to a particular antigen
asthma
local inflammatory reaction to inhaled allergens; type I hypersensitivity