Chapter 13- Cardiovascular System
what 2 structures perform function syncytium?
atrial and ventricular walls
what are the main vessels of the superficial network?
basilic and cephalic veins
pressure and volume changes during cardiac cycle
pressure changes open and close the valves
tachy-
rapid
schematic of a general reflex arc
receptor --> sensory or afferent neurons --> central nervous system --> motor or efferent neurons --> effector (muscle or gland)
electrocardiogram
record of the electrical activity of the heart
pulmonary circulation
send oxygen-poor blood to the lungs to pick up oxygen and unload carbon dioxide
systemic circuit
sends oxygen-rich blood and nutrients to all body cells and remove waste
baroceptor
sensory receptors in aortic arch and carotid arteries that sense changes in blood pressure
brady-
slow
Bradycardia
slow heart rate (less than 60 bpm)
venules
small vessels that gather blood from the capillaries into the veins
internal thoracic artery
branch of subclavian artery; supplies costal and mammary glands
if BP rises
cardiac output increases --> BP increases --> baroreceptors in aortic arch and carotid sinuses are stimulates --> sensory impulses to cardiac center --> parasympathetic impulses to heart --> SA node inhibited --> heart rate decreases --> BP returns towards normal
hepatic portal vein
carries nutrient-rich blood from the capillaries of the villi to the liver, then to the heart
vessels
carrying blood towards the heart
deeper portion of epicardium
contains adipose tissue along the coronary arteries and cardiac veins that provide blood flow throughout the myocardium
external carotid artery
courses upward on the side of the head, giving off branches to structures in the neck, face, jaw, scalp, and base of the skull
Veins from the upper limb and shoulder
deep venous begins in digital veins --> radial veins --> ulnar veins --> brachial veins -superficial veins connect in complex networks beneath the skin -communicate with deep vessels of the upper limb
diastol-
dilation
left and right common carotid arteries
diverge into the internal and external carotid arteries
common iliac artery
divides into internal and external branch
coronary sinus
enlarged vessel on the posterior surface of the heart that empties blood into the right atrium
wall of the heart
epicardium, myocardium, endocardium
capillaries
gas and nutrient exchange
internal iliac artery
gives off many branches to pelvic muscle and visceral structures, gluteal muscles, and external reproductive organs
cardiovascular system
heart and blood vessels make up the cardiovascular system
-gram
something written
cardiac muscle cells
intercalated discs join cardiac muscle cells --> action potential to spread throughout a network of cells --> cardiac muscles contract as a unit
how is BP determined?
(cardiac output) x (vascular resistance)
tricuspid valve
-has 3 tapered projections called cusp -lies between right atrium and right ventricle
What is the heart?
A muscular pump that generates force required for blood to move through the vessels
arteries
carry blood away from the heart
systol-
contraction
arteries
strong, elastic, vessels adapted for transporting blood away from the heart under high pressure
how many liters of blood is pumped per day?
-7,000 liters -2.5 million times in an average lifetime
average adult heart rate
-70-75 beats per minute at rest -60 to 100 beats per minute normal range
venous blood flow
-Blood pressure decreases as the blood moves through the arterial system and into the capillary network, so little pressure remains at the venular ends of the capillaries -instead, blow flow through venous system is only partly direct result of heart action and depends on other factors like skeletal muscle contraction, breathing movements, and vasoconstriction of veins
location of the heart
-In the mediastinum superior to diaphragm -bordered laterally by the lungs -shape of an upside down cone -apex on the bottom -left of the sternum at the level of the 5th rib
cardiac output
-The volume of blood per minute that the heart pumps -Stroke volume x heart rate
intercostal arteries
-arise from thoracic aorta -supply blood to intercostal muscle, the vertebrae, spinal cord, deep muscle of the deep
Factors that influence arterial blood pressure
-blood volume increase -heart rate increases -stroke volume increases -blood viscosity increases -peripheral resistance increases
3 major arteries originate from aortic arch
-brachiocephalic trunk -common carotid artery -left subclavian artery
subclavian artery
-branches toward the neck and continues into arm -passes between the clavicle and 1st rib and becomes the axillary artery
collateral circulation
-circulation formed by smaller blood vessels branching off from or near larger, occluded blood vessels -may supply oxygen and nutrients to the myocardium when coronary artery is blocked
blood vessels
-closed circuit tubes that carries blood from the heart to the body cells and back -consist of arteries, arterioles, capillaries, venules, and veins
brachial artery
-courses along humerus to the elbow -gives rise to deep brachial artery that curves posteriorly around the humerus and supplies triceps brachii muscle -divides into ulnar artery and radial artery
visceral pericardium
-covers the heart -innermost layer
fibrious pericardium
-fibrous bag composed of dense connective tissue -attached to central part of diaphragm, posterior sternum, the vertebral column, and large blood vessels
pulmonary valve
-has 3 cusp -allows blood to leave the right ventricle and prevents backflow into ventricular chamber
systolic pressure
-highest pressure generated by the heart during ventricular contraction. -upper number
endocardium
-inner layer of the wall -consist of epithelial and underlying connective tissue that contains elastic and collagen fibers -contains blood vessels and specialized cardiac muscle fibers(purkinje fibers) -inner lining of blood vessels attached to heart
endothelium(tunica interna)
-innermost layer of artery -composed of squamous epithelium -helps prevent blood clotting by providing smooth surface
aorta
-largest artery in body -extends upward from left ventricle -arches over the heart and to the left -anterior to left of vertebral column
pericardium
-membranous sac enclosing the heart -at proximal end of the large blood vessels
tunica media
-middle layer of artery -includes smooth muscle cells
myocardium
-middle layer of the heart -consist of cardiac muscle tissue that pumps blood out of the heart chambers -lies in planes that are separated by connective tissue richly supplied w/ blood capillaries, lymph capillaries, and nerve fibers
abdominal viscera
-originate in the capillary networks of the stomach, intestines, pancreas, and spleen -carry blood through hepatic portal vein to the liver
azygos vein
-originates from dorsal abdominal wall and ascends through mediastinum on right side of vertebral column to join superior vena cava -drains muscular tissue from most of abdominal and thoracic wall
tunica externa
-outer layer of artery -relatively thin -irregular elastic and collagen fibers -attaches artery to surrounding tissues
epicardium
-outer layer of the heart -protect the heart -serous membrane consist of connective tissue covered by epithelium
parietal pericardium
-outer layer of the pericardium -covers the inner surface of the fibrous pericardium
blood pressure (BP)
-pressure in arteries supplied by branches of aorta (systemic arteries) -clinical blood pressure
skeleton of the heart
-rings of dense connective tissue surrounding the pulmonary trunk and aorta at proximal ends -provide firm attachment for heart valves and muscle fibers -prevent outlets of the atria and ventricles from dilating during contraction
veins from the lower limb and pelvis
-sets of deep and superficial veins drain these regions -popliteal vein --> femoral vein --> external iliac vein
capillaries
-smallest diameter blood vessels -connects the smallest arterioles and smallest venules -extensions of inner linings of arterioles -form semipermeable layer
pericardial cavity
-space between the parietal and and visceral serous layers of the pericardium -contains a small amount of serous fluid
axillary artery
-supplies branches to structure in axilla and chest wall -become brachial artery
diastolic pressure
-the lowest pressure that remains in the arteries before the next ventricular contraction -bottom number
stroke volume
-the volume of blood pumped out by a ventricle with each heartbeat -equals 70 millimeters in an average-weight male at rest
What happens when the muscular wall of the right ventricle contracts
-tricuspid valve is pushed closed by the pressure -blood exits through pulmonary trunk -divides to form left and right pulmonary arteries -leads to
external jugular vein
-veins drain blood from the face, scalp, and superficial regions of the neck -empty into right and left subclavian veins
characteristic of venous pathway
-vessel originate from merging of the capillaries into venules -venules merge into small veins -meet to form larger ones -hard to follow due to irregular networks -larger veins are less variable
heart sounds
1)First sound is lubb, which originates during ventricular systole when AV valve closes 2)Second sound is dubb, which occurs during ventricular diastole when pulmonary and aortic valves close
function syncytium
mass of cells performing as a unit
systole
Contraction of the heart
septum
Divides the right and left chambers of the heart
blood supply to the heart
myocardial cells require a constant supply of oxygen-rich blood. branches of the coronary arteries feed the many capillaries of the myocardium. smaller branches of these arteries typically have connections have collateral circulation
aorta
Largest artery in the body
aortic valve
Opens and allows blood to leave the left ventricle as it contracts
papill-
nipple
diastole
Relaxation of the heart
baroceptor reflex
Rise in arterial pressure stretches the baroreceptors and causes them to transmit signals to reduce HR/CO and vasodilate vessels
path of cardiac impulse
SA node --> atrial syncytium --> junctional fibers --> AV node --> AV bundle --> bundle branches --> purkinje fibers --> ventricular syncytium
atrioventricular valves
Valves located between the atrial and ventricular chambers on each side of the heart, prevent backflow into the atria when the ventricles are contracting.
What is the purpose of the SA node?
pacemaker of the heart
viscosity
a fluid's resistance to flow
cardiac conduction system
a system of specialized muscle tissues that conducts electrical impulses that stimulate the heart to beat
tachycardia
abnormally fast heart rate (>100 bpm)
Blood flow through the heart
superior/inferior vena cava --> right atrium --> tricuspid valve --> right ventricle --> pulmonary valve --> pulmonary trunk --> left and right pulmonary valve --> alveolar capillaries in left and right lung --> left and right pulmonary veins --> left atrium --> mitral valve --> left ventricle --> aortic valve --> aorta --> systemic capillaries in upper, myocardium, and lower body tissues
coronary arteries
supply blood to the tissues of the heart
heart action
systole and diastole
blood volume
the amount of fluid in blood
arteriole
the smallest kind of artery
hepatic portal system
the veins that carry blood from the digestive organs to the liver
syn-
together
veins from the abdominal and thoracic wall
tributaries of the brachiocephalic and azygos veins drain these walls
heart chambers
upper chamber(atria): thin walls and receive blood returning to the heart lower chamber(ventricles): receive blood from the atria and contract to force blood out of the heart into arteries
mitral valve
valve between the left atrium and the left ventricle; bicuspid valve
veins vs arteries
veins have thinner walls that have less smooth muscle and less elastic connective tissue. lumens of veins have a greater diameter