Gabriela Samson P:1 Cardiovascular System
ABO, Rh blood types
Anatomy of the heart (including all chambers, and valves)
Major blood vessels (names arteries and veins)
Structural and functional differences between blood vessel types (arteries, veins,capillaries)
Cardiac cycle and the ECG
Layers of the heart
Vital signs (BP and Pulse)
Major functions of the cardiovascular system
Major components and functions of Blood
Blood flow through the heart and body
For example, if a recipient has type A blood, he/she has antigen A on RBCs and anti-B antibodies in the plasma; This person cannot be given a transfusion of RBCs containing the B antigen.
Eosinophils make up 1 to 3% of circulating leukocytes; kill certain parasites and moderate inflammation
Arteries transport blood away from the heart, veins transport
blood toward the heart, and capillaries are vessels that run
between arteries and veins
Right ventricle has a thinner wall than the left ventricle, because it must pump blood only as far as the lungs, compared to the left ventricle pumping to the entire body
Visceral pericardium (epicardium), the inner layer of the serous membrane, that covers the heart
The pulmonary arteries carry blood to the lungs, where it enters alveolar capillaries, the site of gas exchange with the alveoli of the lungs; here the blood drops off carbon dioxide and picks up oxygen
They consist only of a layer of endothelium, through which
substances are exchanged with tissue cells (diffusion)
During ventricular diastole, pressure inside them increases sharply, causing AV valves to close and the aortic and pulmonary valves to open
Capillary- Single layer of squamous epithelium
Cardiac output (CO): Directly affects blood pressure
The Rh blood group was named after the rhesus monkey.
Main concern is possible agglutination of donor RBCs by antibodies in the recipient's plasma.
In humans, group includes several Rh antigens or factors.
Antibodies of one type will react with antigens of the same type, and cause agglutination.
Most common antigen of the group is antigen D.
In blood transfusions, certain combinations must be avoided.
If the Rh factor (antigen D) is present on a person’s red blood cells, the blood is Rh positive; if absent, the blood is Rh negative
Type O blood has neither on RBC membranes, but both types of antibodies in the plasma; universal donor.
There are no corresponding antibodies in the plasma, unless a person with Rh-negative blood has physical contact with Rh-positive blood; the person will then develop anti-Rh antibodies
Type AB blood has both A and B antigens on RBC membranes, but both types of antibodies in the plasma; universal donor.
There are 2 ways in which an Rh-negative individual can have contact with Rh-positive blood: a transfusion or pregnancy
Type B blood has B antigens on RBC membranes and anti-A antibodies in the plasma.
Type A blood has A antigens on RBC membranes and anti-B antibodies in the plasma.
If an Rh-negative woman carries an Rh-positive baby, she may be exposed to the Rh-positive blood during delivery:
The mother will now make anti-Rh antibodies that could attack the blood of a future Rh-positive baby; this is called erythroblastosis fetalis, or hemolytic disease of the fetus or
newborn.
Blood types are inherited.
The problem can be prevented by giving the mother the drug, RhoGAM, a type of anti-Rh antibody that binds to and shields the fetus’s RBCs from the mother’s immune system; this can be given at week 28 of pregnancy, and prevents the mother from producing anti-Rh antibodies
Blood groups are based on presence or absence of 2 important antigen on RBC membranes: Antigen A and Antigen B.
During ventricular systole, papillary muscles contract, pulling on chordae tendineae and preventing the backflow of blood through the AV valves
Pressure inside atria rises further as they contract, forcing the remaining blood into the ventricles
As blood is pushed out of the ventricles, the pressure drops, and the ventricles relax
70% of blood flows passively from atria into ventricles before the atria contract
When the ventricular pressure is lower than the blood pressure in the aorta and pulmonary truck, the semilunar valves close
During early ventricular diastole, pressure in the atria is greater than that of the ventricles, which forces the AV valves open; this allows ventricles to fill
Once ventricular pressure is lower than atrial pressure, the AV valves open and the process begins again
Pressure changes open and close heart valves
Average adult resting heart rate: 70 to 75 beats/minute (bpm), with normal range of 60 to 100 bpm
During the cardiac cycle, pressure within the heart chamber rises and falls with the contraction and relaxation of atria and ventricles
Resting heart rate >100 bpm is tachycardia; <60 bpm is bradycardia
T Wave: Corresponds to ventricular repolarization, and leads to ventricular relaxation
The amount of blood pumped at any one time must adjust to the current needs of the body
QRS Complex: Corresponds to the depolarization of ventricles, which leads to contraction of the ventricles; the repolarization of the atria occurs during the QRS complex, but is hidden behind the larger ventricular event.
If a person is exercising, more blood is needed by the skeletal muscles, and the heart rate increases
Components of the ECG: P Wave: The first wave, which corresponds to the depolarization of the atria; this leads to the contraction of the atria
Heart rate changes in response to the autonomic nervous system:
Recording results from the summed action potentials of many cardiac muscle cells, which can be detected through electrical currents in the body fluids
Sympathetic impulses increase the speed and strength of heart contractions
Electrocardiogram (ECG): a recording of the electrical changes that occur during a cardiac cycle
Heart rate is decreased by parasympathetic impulses
A constant exchange of respiratory gases, nutrients, and metabolic wastes occurs between capillaries and tissue fluid near the body cells, via mostly diffusion
They connect small arterioles to small venules
Blood entering capillaries contains high concentrations of oxygen and nutrients, that diffuse from the capillaries into the tissues
Capillaries are blood vessels with the smallest diameter
Carbon dioxide and metabolic wastes diffuse from the tissue fluid into the capillaries
Walls of arterioles get thinner as they approach the capillaries
Direction of diffusion depends on concentration gradients
This sympathetic control of arteries and arterioles is used to
regulate blood flow and blood pressure
Blood pressure (BP) moves blood through lumen of arteries and arterioles
When vasomotor impulses are inhibited, vasodilation results
BP decreases with distance from heart, so BP is greatest in arteries, lower in arterioles, and even lower in capillaries (and lowest in veins)
Sympathetic stimulation causes muscle contraction, resulting in vasoconstriction of arteries
BP is higher in arteriolar end of capillaries than in the venular end
Tunica externa: Outermost connective tissue layer; relatively
thin; attaches the artery to surrounding tissues
Venules leading from capillaries merge to form larger veins, that return blood to the heart
Tunica media: Thick middle layer, composed of smooth muscle
Walls of veins have the same three layers as arteries, except that the muscle layer is thinner, and they have flap-like valves to prevent backflow of blood
Tunica interna: Innermost endothelial layer composed of simple squamous epithelium; creates a smooth surface to prevent clots; secretes biochemicals to prevent platelet aggregation; secretes substances to regulate blood flow
Lumen of a vein is larger than that of an artery
The wall of an artery consists of 3 layers:
Blood pressure in a vein is lower than that of an artery
Arteries become smaller as they divide and give rise to arterioles
Veins also function as blood reservoirs; vasoconstriction of veins in times of blood loss can almost restore normal BP after 25% of blood being lost to a hemorrhage
Arteries usually transport blood away from the heart
Contractions of skeletal muscle squeeze blood back up veins one valve section at a time
Arteries are strong, elastic vessels adapted for carrying high-
pressure blood
Blood vessels: Arteries, Arterioles, Capillaries, Venules, Veins
The blood vessels form a closed circuit that carries blood away from the heart, to the cells, and back again
disorders of the cardiovascular system
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Cerebrovascular Accident (Stroke)- Blood flow to a portion of the brain is interrupted (stroke).
Endocarditis & Myocarditis- Inflammation of the heart.
Peripheral Artery Disease (PAD)- Arteries harrow and reduce blood flow to extremities.
Congenital Heart Disease- Issue with heart structure and function present from birth.
Myocardial Infarction (Heart Attack)- Blood flow to part of the heart is blocked (Heart attack).
Function- Allows nutrients, gases, and wastes to be exchanged between the blood and tissue fluid; connects an arteriole to a venule
Function- Connects an artery to a capillary; helps control blood flow into a capillary by vasoconstriction or vasodilating
Venule- Thinner wall than in an arteriole, less smooth muscle and elastic connective tissue
Arteriole- Thinner wall than an artery but with three layers; smaller arterioles have an endothelial lining, some smooth muscle tissue, and a small amount of connective tissue
Function- Connects a capillary to a vein
Function- Transports blood under relatively high pressure from heart to arterioles
Vein- Thinner wall than an artery but with similar layers; the vein middle layer is much thinner; some veins have flap like valves
Artery- Thick, strong wall with three layers—an endothelial lining, a middle layer of smooth muscle and elastic connective tissue, and an outer layer of connective tissue
Function- Transports blood under relatively low pressure from a venule to the heart; valves prevent backflow of blood; serves as a blood reservoir
Cardiac output = stroke volume × heart rate
Arterial pressure depends on many factors, including cardiac
output, blood volume, peripheral resistance, and blood viscosity
Stroke volume: amount of blood discharged from each
ventricle with each contraction (about 70 mL)
Common pulse points include the radial artery, carotid artery,
brachial artery, and femoral artery
Heart rate: number of heart beats per minute (average is 72
beats/min)
The alternating expansion and recoil of the wall of an artery as the ventricles contract and relax can be felt at certain points in the body as a pulse
Average CO = 70 mL/beat × 72 beats/min = 5040 mL/min
BP decreases as distance from the left ventricle increases
If stroke volume or heart rate increases, so does the cardiac
output
A BP of no greater than 120/80 (systolic/diastolic) at rest is
considered normal
Peripheral resistance: Friction between blood and the walls of blood vessels is a force called
A sphygmomanometer is used to measure arterial blood pressure
Peripheral resistance (PR) hinders blood flow; blood pressure (BP) has to overcome PR in order to keep flowing
Diastolic pressure: minimum arterial pressure reached during ventricular relaxation (diastole), just before the next contraction
Viscosity: Difficulty with which molecules in a fluid flow past each other
Systolic pressure: maximum arterial pressure reached during ventricular contraction (systole)
The greater the blood viscosity, the greater its resistance to flow, and the greater the blood pressure
Arterial blood pressure rises and falls according to a pattern established by the cardiac cycle:
Blood pressure is determined by cardiac output (CO) and peripheral resistance (PR) BP = CO × PR
The term "blood pressure" usually refers to systemic arterial
pressure
The body maintains normal blood pressure by adjusting cardiac output and peripheral resistance
BP exists all through the cardiovascular system
Frank-Starling law of the heart is the relationship between cardiac muscle cell length and force of contraction:
Force blood exerts against the inner walls of blood vessels
As venous blood returns to the heart, the greater the length of stretched cardiac muscle fibers (cells), the stronger the ventricular contraction that will follow
Therefore, the volume of blood that is pumped out of the heart is the same as the volume that enters the heart
A stronger contraction increases stroke volume and cardiac output
Basophils account for <1% of leukocytes; promote inflammation by secreting heparin and histamine
Neutrophils comprise 50 to 70% of leukocytes; strong
phagocytes
Agranulocytes: Do not have granular cytoplasm, have a longer life-span
Granulocytes: Have granular cytoplasm, short life-span (about 12 hours)
Monocytes make up 3 to 9% of circulating leukocytes; are
strong phagocytes; migrate to some tissues and differentiate
into macrophages
WBCs can leave the bloodstream to fight infection, by squeezing between cells of wall of small blood vessels
Lymphocytes are long-lived (many years); account for 25 to 33% of circulating leukocytes; responsible for immunity; attack specific foreign pathogens
They are formed from hemocytoblasts (hematopoietic stem cells) in red bone marrow
Platelets or thrombocytes are fragments of large cells in the red bone marrow
White blood cells (WBCs, leukocytes) help defend the body against disease
Platelets help repair damaged blood vessels by adhering to their broken edges; the stoppage of bleeding is called hemostasis
When oxygen is released, deoxyhemoglobin is darker in red color
Low platelet count increases risk of internal bleeding
When oxygen combines with hemoglobin, it forms oxyhemoglobin, which gives blood its bright red color
Plasma is the clear, straw-colored liquid part of the blood
Hemoglobin transports oxygen and some carbon dioxide through the blood
Cells and platelets are suspended in the plasma
RBCs contain one-third hemoglobin
Plasma is mostly water (92%) but contains a variety of substances
Red Blood Cells (Erythrocytes, RBCs): Biconcave disks; this shape makes the RBCs flexible as they travel through
blood vessels, puts oxygen in close proximity to the hemoglobin, and increases surface area for gas exchange
Plasma functions: transport nutrients and gases, regulate fluid and electrolyte balance, and maintain an optimal pH
Red blood cells, white blood cells, and platelets are called the formed elements of the blood
The blood contains red blood cells (for respiratory gas transport), white blood cells (for fighting infection), platelets (for stoppage of bleeding), and plasma (the liquid matrix)
Blood transports nutrients and oxygen to the body cells, and
removes metabolic wastes and carbon dioxide
Blood transports substances throughout the body, helps to
maintain homeostasis and distributes heat
Blood, heart, and blood vessels make up the circulatory system
Blood: a type of connective tissue with a fluid matrix (plasma)
Pericardial cavity, the space between the visceral and parietal layers,which contains serous fluid for reducing friction between the layers
Parietal pericardium, the outer layer of the serous membrane, which lines the inner surface of the fibrous pericardium
The wall of the heart is composed of 3 layers:
The inner, more delicate, double-layered serous pericardium,
which consists of:
Epicardium (visceral pericardium): the outermost layer; a
serous membrane made up of connective tissue and
epithelium; decreases friction in the heart
The outer, tough, connective tissue fibrous pericardium
Myocardium: the middle layer; consists of cardiac muscle, and is the thickest layer of the heart wall; pumps blood out of heart chambers
The pericardium is a membranous sac that encloses the heart. Pericardium consists of 2 portions:
Endocardium: the inner layer; made up of connective tissue and epithelium; continuous with the endothelium of major vessels joining the heart; contains the Purkinje fibers (part of the cardiac conduction system)
Oxygen-poor blood is carried by the pulmonary circuit to the
lungs, where it picks up oxygen and drops off carbon dioxide
A functional cardiovascular system is vital for supplying oxygen and nutrients to tissues and removing wastes from them
The systemic circuit sends oxygen-rich blood to all body cells,where it drops of oxygen and picks up carbon dioxide
Cardiovascular system: a closed circuit that consists of the heart and blood vessels (arteries, capillaries, and veins)
Each side of the heart has a semilunar valve between the ventricle and the blood vessel into which blood is pumped:
Coronary sinus drains blood from the myocardium (coronary circulation) into the right atrium
Right ventricle pumps blood to the lungs through the pulmonary trunk; at the base of the pulmonary trunk is the pulmonary semilunar valve, which prevents backflow of blood into the right ventricle
Superior and inferior vena cava(e) bring blood back from the systemic circuit to the right atrium
Left ventricle pumps blood to the systemic circuit through the aorta; at the base of the aorta is the aortic semilunar valve, which prevents backflow of blood into the left ventricle
Chordae tendinae are attached to papillary muscles in the inner wall of the heart; these muscles contract during ventricular contraction to prevent the backflow of blood through the AV valves
The right AV (tricuspid) valve and left AV (bicuspid or mitral) valve have cusps to which chordae tendinae attach
Each side has an atrioventricular (AV) valve to ensure one-way flow of blood from atria to ventricle
The interventricular septum separates the ventricle on the right from the left
The thick-muscled ventricles pump blood out of the heart
Atria receive blood returning to the heart; have thin walls and ear-like auricles projecting from their exterior
The heart contains 4 chambers: 2 upper chambers called atria, and 2 lower chambers called ventricles
Oxygen-rich blood flows back to the left atrium of the heart via pulmonary veins
The right ventricle contracts, closing the tricuspid valve, and forcing blood through the pulmonary semilunar valve into the pulmonary trunk and arteries
The left atrium pumps blood through the mitral (bicuspid) valve into the left ventricle
The right atrium contracts, forcing blood through the tricuspid valve into the right ventricle
The left ventricle contracts, closing the mitral valve, opening the aortic semilunar valve, and pumping blood into the aorta for distribution to the systemic circuit of the body.
Oxygen-poor blood returns to the right atrium via the superior and inferior venae cava and coronary sinus
Right and left coronary arteries: first branches off the aorta, which carry oxygen-rich blood to the heart
Systemic circuit: Blood flow between heart and body tissues
Branches of the coronary arteries feed many capillaries of the myocardium
Pulmonary circuit: Blood flow between heart and lungs
Branches of coronary arteries often have connections called
anastomoses; these provide alternate pathways for blood, in case a pathway becomes blocked
Two circuits, or subdivisions, for blood flow with respect to gas exchange:
Cardiac veins drain blood from the heart muscle, and carry it to the coronary sinus, a large vein that empties into the right atrium
Blood flow proceeds in a continuous circle