Functions of the circulatory system
Transportation, regulation, protection
Major components of the circulatory system
Cardiovascular system and lymphatic system
Components of the cardiovascular system
arteries, arterioles, veins, venules, capillaries
Components of the lymphatic system
Lymphatic vessels, lymphoid tissues, lymphatic organs (spleen, thymus, tonsils, lymph nodes)
Average adult blood volume is ___ liters.
5
bright red, oxygenated except for blood going to the lungs
Arterial Blood
dark red, deoxygenated except for blood coming from the lungs
Venous blood
Blood is made of __% formed elements and __% plasma (by volume)
45; 55
Plasma protein that creates osmotic pressure to help draw water from tissues into capillaries to maintain blood volume and pressure
albumin
Globulins that transport lipids and fat-soluble vitamins
alpha and beta globulins
Globulins are proteins found in the
plasma
Plasma proteins make up _% to _% of plasma
7 to 8
Globulins that are antibodies that function in immunity
Gamma globulins
Plasma without fibrinogen
Serum
Helps in clotting after becoming fibrin
Fibrinogen
What do osmoreceptors in the hypothalamus do
Cause the release of ADH from the posterior pituitary gland if fluid is lost or osmolality increases
Formed elements of the blood
Erythrocytes, Leukocytes, Platelets
Abnormally low hemoglobin or RBC count
Anemia
Erythrocytes characteristics (7)
Flattened, biconcave discs
Carry oxygen
Lack nuclei and mitochondria
Count – approximately 5 million/mm3 blood
Have a 120-day life span
Each contain about 280 million hemoglobin molecules
Iron heme is recycled from the liver and spleen; carried by transferrin in the blood to the red bone marrow
Granular leukocytes
neutrophils, eosinophils, and basophils
Agranular leukocytes
monocytes and lymphocytes
Leukocytes characteristics
Have nuclei and mitochondria
Count – approximately 5000 to 9000/mm3 blood
movement through the capillary wall into connective tissue
Diapedesis
How do leukocytes move
Amoeboid fashion
Smallest formed element, fragments of large cells called megakaryocytic
Platelets (thrombocytes)
Platelets characteristics
Lack nuclei
Very short-lived (5 to 9 days)
Clot blood with several other chemicals and fibrinogen
Release serotonin that stimulates vasoconstriction
Count: 130,000 to 400,000/mm3 blood
Formation of blood cellular components is called
Hematopoiesis (hemopoiesis)
embryonic cells that give rise to all blood cells
Hematopoietic stem cells
Where does Hematopoiesis (hemopoiesis) occur
Myeloid (red bone marrow) and lymphoid tissue
Formation of red blood cells is called
Erythropoiesis
Red bone marrow produces how much RBCs/Sec
2.5 million
Regulation of erythropoiesis occurs through
Process stimulated by erythropoietin from the kidneys that respond to low blood O2 levels
Process takes about 3 days
Most iron in RBC formation comes from
Recycled RBCs, the rest from diet.
Intestinal iron secreted into blood through
ferroportin channels
All iron travels in blood bound to
Transferrin
Iron homeostasis hormone which removes ferroportin channels to promote cellular storage of iron and lowers plasma iron levels
Hepcidin
Formation of white blood cells is called
Leukopoiesis
What stimulates the production of different leukocytes?
Cytokines
What are the different subtypes of leukocytes (5)
Multipotent growth factor-1 Interleukin-1 Interleukin-3 Granulocyte colony stimulating factor Granulocyte-monocyte colony-stimulating factor
stimulates growth of megakaryocytes and maturation into platelets
Thrombopoietin
has the A antigen (RBC)
Type A
has the B antigen (RBC)
Type B
has both the A and B antigens (RBC)
Type AB
has neither the A nor the B antigen (RBC)
Type O
found on the surface of cells to help immune system recognize self cells
Antigens
secreted by lymphocytes in response to foreign cells
Antibodies
has anti-B antibodies (plasma)
Type A
has anti-A antibodies (plasma)
Type B
has no antibodies (universal recipient) (plasma)
Type AB
has anti-A and anti-B antibodies (universal donor) (plasma)
Type O
Transfusion reaction
If a person is given wrong blood, antibodies bind to erythrocytes and cause agglutination
Antigen for Rh factor
Antigen D
Will not have antibodies unless exposed to Rh+ either through blood transfusion or pregnancy
Rh-
Rh- mothers are treated with what in future pregnancies if their first child was Rh+
RhoGAM. Antibodies cross placenta and attack Rh+ RBCs of new fetus.
cessation of bleeding when a blood vessel is damaged
Hemostasis
Damage exposes collagen fibers to blood, producing (3)
Vasoconstriction
Formation of platelet plug
Formation of fibrin protein web
Prostacyclin, nitric acid, and CD39 are secreted by
intact endothelium
Prostacyclin and nitric acid in endothelium do what?
Vasodilate and inhibit platelet aggregation
CD39 do what?
Breaks down ADP into AMP and Pi to inhibit platelet aggregation further
What holds platelets at damaged endothelium
von Willebrand factor
Damaged endothelium exposes
collagen
Platelet release reaction molecules (3)
ADP (sticky platelets) Serotonin (vasoconstriction) Thromboxane A (sticky platelets and vasoconstriction)
Intrinsic conversion of fibrinogen to fibrin
Activated by exposure to collagen. Factor VII activates a cascade of other blood factors.
Extrinsic conversion of fibrinogen to fibrin
Induced by tissue thromboplastin (factor iii). More direct pathway.
Steps of formation of fibrin (3)
Fibrinogen is converted to fibrin via one of two pathways.
Calcium and phospholipids (from the platelets) convert prothrombin to the active enzyme thrombin, which converts fibrinogen to fibrin.
Vitamin K is needed by the liver to make several of the needed clotting factors.
Drug that blocks thrombin to prevent clots
Heparin
Drug that inhibits vitamin K
Coumadin
What digests fibrin after a blood clot
Plasmin
Right atrium of heart does what
Receives deoxygenated blood from body
Right ventricle of heart does what
Pumps deoxygenated blood to lungs
Left atrium of heart does what
Receives oxygenated blood from lungs
Left ventricle of heart does what
Pumps oxygenated blood to body
Annuli fibrosi rings do what?
Hold the heart valves
Circulation between heart and lungs
Pulmonary
Circulation between heart and body
Systemic
Blood pumps to lungs via
Pulmonary arteries
Blood returns to heart from lungs via
Pulmonary veins
Blood pumps to tissues via
aorta
Blood returns to heart from tissues via
Superior and inferior vena cava
Valve located between the atria and the ventricles
Atrioventricular valves
AV located between right atrium and right ventricle
Tricuspid valve
AV located between between left atrium and left ventricle
Bicuspid valve
Prevent heart valves from inverting
Papillary muscles and chordae tendineae
Valves located between the ventricles and arteries leaving the heart
Semilunar valves
SV between right ventricle and pulmonary trunk
Pulmonary valve
SV between left ventricle and aorta
aortic valve
“Lub”
closing of AV valves; occurs at ventricular systole
“Dub”
closing of semilunar valves; occurs at ventricular diastole
Rheumatic fever (from strep throat) can cause mitral valve flaps to thicken or fuse.
Mitral stenosis
Causes for a heart murmur (3)
Mitral stenosis.
Incompetent valves.
Septal defects.
Contraction of heart muscles
Systole
Relaxation of heart muscles
Diastole
total volume of blood in the ventricles at the end of diastole
End-diastolic volume
the amount of blood left in the left ventricle after systole (1/3 of the end-diastolic volume)
End-systolic volume
isovolumetric contraction
Ventricles begin contraction, pressure rises, and AV valves close (lub)
After isovolumetric contraction,
pressure builds, semilunar valves open, blood is ejected into arteries
After blood is ejected into arteries,
Pressure in ventricles falls; semilunar valves close (dub); isovolumetric relaxation
slight inflection in pressure during isovolumetric relaxation
Dicrotic notch
Cardiac muscle cells are interconnected by gap junctions called
Intercalated discs
The area of the heart that contracts from one stimulation event is called a
myocardium or functional syncytium
automatic nature of the heartbeat
Automaticity
is the “pacemaker”; located in right atrium
Sinoatrial node (SA node)
secondary pacemakers (ectopic pacemakers); slower rate than the “sinus rhythm”
AV node and Purkinje fibers
Slow spontaneous depolarization after a rapid hyperpolarization
Pacemaker potential (diastolic depolarization)
At -40mV, what happens
Ca2+ gated channels open, triggering contraction
Repolarization occurs with the opening of voltage-gated
K+ channels
HCN channels
Speeds heart rate due to increased Na+
Parasympathetic releases acetylcholine which,
opens K+ channels to slow the heart rate
Cardiac muscle cells have a resting potential of
-85 mV
ECG atrial depolarization
P wave
ECG atrial systole
P-Q interval
ECG ventricular depolarization
QRS wave
ECG plateau phase, ventricular systole
S-T segment
ECG ventricular repolarization
T wave
Lead I
Between right arm and left arm
Lead II
between right arm and left leg
Lead III
Between left arm and left leg
AVR Lead
Right arm VS Left arm and Left leg
AVL Lead
Left arm VS Right arm and Left foot
AVF Lead
Left leg VS Right arm and Left Arm
“Lub” occurs after
The QRS wave as the AV valve closes
“Dub” occurs at the beginning
T wave as SL valve closes
abnormal patterns of electrical activity that result in abnormalities of the heartbeat
Arrhythmias
Group 1 Arrhythmia drugs
drugs that block the fast Na+ channels (quinidine, procainamide, lidocaine)
Group 2 Arrhythmia drugs
drugs are beta-blockers (propranolol, atenolol)
Group 3 Arrhythmia drugs
drugs block K+ channels (amiodarone)
Group 4 Arrhythmia drugs
drugs block the slow Ca2+ channels (verapamil, diltiazem)
inner layer; composed of simple squamous endothelium on a basement membrane and elastic fibers
Tunica interna
middle layer; composed of smooth muscle tissue
tunica media
outer layer; composed of connective tissue
tunica externa
Arteries closer to the heart; allow stretch as blood is pumped into them and recoil when ventricles relax
Elastic arteries
Arteries farther from the heart; have more smooth muscle in proportion to diameter; also have more resistance due to smaller lumina
Muscular arteries
Arteries 20 to 30 µm in diameter; provide the greatest resistance; control blood flow through the capillaries
Arterioles
blood flow to capillaries is regulated by
vasoconstriction and vasodilation of arterioles
precapillary sphincters
Capillaries Adjacent cells are close together; found in muscles, adipose tissue, and central nervous system (add to blood-brain barrier)
Continuous capillaries
Capillaries have pores in vessel wall; found in kidneys, intestines, and endocrine glands
Fenestrated capillaries
Capillaries have gaps between cells; found in bone marrow, liver, and spleen; allow the passage of protein
Discontinuous capillaries
Ensure one-directional flow of blood returning to heart
Venous valves
Muscle surrounding the veins to help pump blood
Skeletal muscle pumps
carry cholesterol to arteries
Low density lipoprotein (bad)
carry cholesterol away from the arteries to the liver for metabolism
High density lipoprotein (good)
better predictor for atherosclerosis than LDL levels
C-reactive proteins
condition characterized by inadequate oxygen due to reduced blood flow
Ischemia
Common cause for ischemia
Atherosclerosis
Angina pectoris
Referred pain due to increase build up of lactic acid due to ischemia
Ischemia leads to necrosis in some parts of the heart which leads to
Myocardial infarction (heart attack or MI)
Detecting ischemia
Depression of S-T on ECG. Plasma concentration of blood enzymes. Creatine phosphokinase. Lactate dehydrogenase. Troponin I (sensitive). Troponin T.
slow heart rate, below 60 bpm is called
bradycardia
fast heart rate, above 100 bpm
tachycardia
AV Node Block
Damage to the AV node can be seen in changes in the P-R interval of an ECG
AV Node Block First Degree
Impulse conduction exceeds 0.2 secs.
AV Node Block Second Degree
Not every electrical wave can pass to ventricles
AV Node Block Third/Complete Degree
No stimulation gets through. A pacemaker in the Purkinje fibers takes over, but this is slow (20 to 40 bpm).
Functions of the Lymphatic System
Transports excess interstitial fluid (lymph) from tissues to the veins.
Produces and houses lymphocytes for the immune response.
Transports absorbed fats from intestines to blood.
formed from merging lymphatic capillaries
Lymphatic ducts: lymph is filtered through lymph nodes
smallest lymphatic vessel; found within most organs
Lymphatic capillaries: Interstitial fluids, proteins, microorganisms, and fats can enter.
Lymph is delivered to what veins
Left and right subclavian veins
the volume of blood pumped each minute by each ventricle is called
Cardiac output
Cardiac output =
stroke volume x heart rate
Spontaneous depolarization occurs at SA node when
HCN channels open, allowing Na+ in
Sympathetic norepinephrine and adrenal epinephrine keep HCN channels open
Increasing heart rate
Parasympathetic acetylcholine opens K+ channels
Slowing heart rate
Spontaneous depolarization occurs at SA node and is controlled by
cardiac center of medulla oblongata that is affected by higher brain centers
Positive chronotropic effect
Increases rate
Negative chronotropic effect
Decreases rate
Stroke volume increases with increased (2)
EDV and contractility
Stroke volume regulated by
EDV, arterial blood pressure, contractility
Arterial blood pressure is inversely related to
stroke volume
Strength of ventricular contraction
contractility
How much of the EDV is normally ejected
60%, Ejection fraction
Frank-Starling Law of the Heart
Increased EDV results in increased contractility and thus increased stroke volume
myocardial stretch
Increased EDV stretches the myocardium, which increases contraction strength.
Due to increased myosin and actin overlap and increased sensitivity to Ca2+ in cardiac muscle cells.
Increased peripheral resistance will decrease
Stroke volume
2/3 of our body water is found in
the cells
of remaining 1/3 of water, 80% is found in and 20% in
Intersitial and blood plasma
Net filtration pressure
hydrostatic pressure of the blood in the capillaries minus the hydrostatic pressure of the fluid outside the capillaries
Combination of hydrostatic pressure and oncotic pressure that predicts movement of fluid across capillary membranes
Starling forces
(pc + πi) - (pi + πp); (fluid out)-(fluid in)
fluid movement
predict the movement of fluid out of the capillaries at the arteriole end (positive value) and into the capillaries at the venule end (negative value)
Starling forces
Excessive accumulation of interstitial fluid
Edema
Causes of edema (6)
High arterial blood pressure
Venous obstruction
Leakage of plasma proteins into interstitial space
Myxedema (excessive production of mucin in extracellular spaces caused by hypothyroidism)
Decreased plasma protein concentration
Obstruction of lymphatic drainage
Capillaries in the kidneys are called
Glomeruli
Kidney arterioles dilate
increasing blood flow and increases urine production that will decrease blood volume
ADH is produced where
Hypothalamus and released in the post pituitary
Secreted by adrenal cortex indirectly when blood volume and pressure are reduced
Aldosterone
Stimulates reabsorption of salt and water in kidneys
Aldosterone
When blood pressure is low, cells in the kidneys (juxtaglomerular apparatus) secrete the enzyme
Renin
Arterial blood pressure =
cardiac output x total peripheral resistance