Chapter 13- Cardiovascular System

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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


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