A&P 2 Lecture 11

P wave

atrial depolarization; occurs just prior to atrial contraction

intercalated discs

between cardiac muscle cells contain desmosomes for structural support, and gap junctions to spread action potentials through a network of cells

venules

receive blood from the capillaries, and conduct it to veins

left ventricle

receives blood from the left atrium; pumps blood to systemic circuit

left atrium

receives blood from the pulmonary veins; pumps blood to left ventricle

right ventricle

receives blood from the right atrium; pumps blood to lungs

right atrium

receives blood returning from systemic circuit (from the superior and inferior vena cave and coronary sinus); pumps blood to right ventricle

diastole

relaxation of a heart chamber

superior and inferior venae cavae

return oxygen poor blood to the heart

pulmonary veins (4)

return oxygen rich blood from lungs to left atrium

interatrial septum

separates left and right atria

inter ventricular septum

separates left and right ventricles

mitral (bicuspid) valve

separates left atrium from left ventricle

aortic semilunar valve

separates left ventricle from aorta

tricuspid valve

separates right atrium from right ventricle

pulmonary semilunar valve

separates right ventricle from pulmonary trunk

1. right atrium 2. tricuspid valve 3. right ventricle 4. right atrioventricular orifice 5. pulmonary semilunar valve 6. pulmonary trunk 7. lungs 8. left atrium 9. pulmonary veins 10. mitral valve 11. left ventricle 12. left atrioventricular orifice 13. aortic semilunar valve 14. aorta

blood flow through the heart, lungs and tissues: -oxygen poor blood from the vena cave and coronary sinus enter _____1______ -blood flows from right atrium, through _____2____, into ____3____ -right atrium contracts, sending remaining blood into right ventricle -right ventricle contracts -tricuspid valve closes _______4______ -as pressure rises in right ventricle, ____5______ opens -blood flows into ____6____ -blood flows to ___7___, drops off carbon dioxide, picks up oxygen -blood returns to ___8____ via ____9____ -blood flows from left atrium, through ____10____ into ____11___ -left atrium contracts, sending remaining blood into left ventricle -left ventricle contracts -mitral valve closes ____12_____ -as pressure rises in left ventricle, _____13_____ opens -blood flows into _____14____ transporting oxygen rich blood to body cells

circumflex branch and anterior inter ventricular artery

branches of left coronary artery

posterior inter ventricular artery and right marginal branch

branches of right coronary artery

precapillary sphincters

capillary blood flow regulated mainly by _________ _______: smooth muscle surrounding capillary when it branches off arteriole or metarteriole

functional syncytium -in the atrial walls; called the atrial syncytium -in the ventricular walls; called the ventricular syncytium

cardiac muscle cells can form a ___________ _______, mass of merging cells that function as a unit

pulmonary circuit

carries oxygen poor blood from heart to lungs, drops off carbon dioxide, picks up oxygen, flows back to the heart

junctional fibers

conduct impulses from SA node to AV node

internodal atrial muscle

conducts impulses from SA node to atria

AV (atrioventricular) node

conducts impulses to AV bundle; delays impulse, so that atria finish contracting before ventricles contract

cardiovascular system

consists of the heart and blood vessels

systole

contraction of a heart chamber

parietal pericardium

deep to fibrous pericardium; outer layer of serous membrane

cardiac veins

drain blood from myocardium; paths of veins lie nearly parallel to those of coronary arteries

coronary sinus

enlarged vein into which other cardiac veins drain; drains into right atrium

auricles

flap like projection from atria, which also atrial expansion

regulation of the cardiac cycle

heart rate and volume of blood pumped change to meet requirements

pericardial cavity

space between visceral and parietal layers of serous pericardium

cardiac conduction system

specialized group of cardiac muscle cells, which initiate and distribute cardiac action potentials through myocardium

visceral pericardium

inner layer of serous membrane; attached to surface of heart; also called the epicardium

endocardium

inner layer of the heart, thin; Membrane of epithelium and underlying connective tissue, and includes blood vessels and specialized fibers; Forms a protective inner lining of the chambers and valves

tunica interna

innermost layer of arteries, endothelium

heart

is a hollow, cone shaped, muscular pump; generates force to transport respiratory gases, nutrients, and wastes through body

atria

thin walled upper chambers; receive blood returning to heart

filtration

•Hydrostatic pressure forces molecules through membrane •Pressure is derived from ventricular contraction

major components of the cardiac conduction system

- SA (sinoatrial) Node - Internodal Atrial Muscle - Junctional fibers - AV (Atrioventricular) Node - AV (Atrioventricular) Bundle (of HIS) - Left & Right bundle branches - Purkinje fibers

blood vessels

-are organs of the cardiovascular system -form a closed circuit, transporting blood from heart to body cells (or lungs) and back to the heart

arteries

-carry blood away from the ventricles of the heart -thick, strong wall -transport blood under high blood pressure -3 layers: tunica interna, media and externa -can undergo vasoconstriction and vasodilation

pericardium (pericardial sac)

-covering over heart and proximal ends of large blood vessels -made up of serous membranes and connective tissue

pressure and volume changes of a cardiac cycle

-during a cardiac cycle, the pressure in the heart chambers rises and falls -pressure changes open and close the valves

fenestrated capillaries

-have large openings in cell membranes and between endothelial cells -found in endocrine glands, kidneys, small intestine

sinusoidal capillaries

-have largest openings; spaces between cells are small cavities -discontinuous -found in liver, spleen, and red bone marrow

continuous capillaries

-have small openings -found in muscle, connective and nervous tissues, and skin

other factors that affect heart rate

-impulses from hypothalamus and cerebrum -body temperature -levels of K+ and Ca+2

stretch receptors in vena cavae

-increase in blood pressure stretches receptors -sympathetic cardioaccelerator reflex increases heart rate and force of contraction, to lower venous pressure

capillary permeability

-openings in walls of capillaries are thin slits found where endothelial cells overlap -sizes of openings may vary among tissues; permeability varies with size of slits

arterioles

-receive blood from the arteries and carry it to the capillaries -smaller and thinner walled -3 same layers or tunic -can undergo vasoconstriction and vasodilation

veins

-receive blood from venules, and carry it back to the atria of the heart

skeleton of the heart

-rings of dense of connective tissue surround origins of pulmonary trunk and aorta, and orifices between atria and ventricles -provide attachments for heart valves and muscle fibers -prevent excess dilation of heart chambers during contraction -These rings, along with other fibrous masses in the interventricular septum, make up the _______ ___ ______ ______

"Lubb"

-the first heart sound (S1) -occurs during ventricular systole -associated with closing of the AV valves

"dupp"

-the second heart sound (S2) -occurs during ventricular diastole -associated with closing of the pulmonary and aortic semilunar valves

epicardium, myocardium, endocardium

3 layers of the heart wall

coronary arteries

left and right ______ ______ supply blood to tissues of the heart -the ______ ______ are first 2 branches of the aorta

aortic valve

location: entrance to aorta; Prevents blood from moving from the aorta into the left ventricle during ventricular relaxation

pulmonary valve

location: entrance to pulmonary trunk; Prevents blood from moving from the pulmonary trunk into the right ventricle during ventricular relaxation

mitral valve

location: left atrioventricular orifice; Prevents blood from moving from the left ventricle into the left atrium during ventricular contraction

tricuspid valve

location: right atrioventricular orifice; prevents blood from moving from the right ventricle into the right atrium during ventricular contraction

murmur

Abnormal heart sound derived from incomplete closure of cusps of a valve

greater

At arteriolar end of capillary, H2O and other substances leave capillary by filtration because hydrostatic pressure is _______ than colloid osmotic pressure

tunica media

middle layer of arteries, made up of smooth muscle and elastic tissue

myocardium

middle thickest layer of heart; Cardiac muscle tissue separated by connective tissue and includes blood and lymph capillaries and nerve fibers; Contracts to pump blood from the heart chambers

exchanges in the capillaries

Capillaries exchange gases, nutrients, and metabolic byproducts between blood and tissue around cells. Exchange occurs by these 4 methods: diffusion, filtration, osmosis, transyctosis

capillary arrangement

Higher the metabolic rate in a tissue, the denser its capillary networks •Rich capillary supply in muscle and nerve tissue, since they use a large amount of O2 and nutrients •Tissues with lower metabolic rate, such as cartilage, have fewer capillaries Capillary patterns differ; some directly connect arterioles to venules, others branch out into complex networks

Purkinje fibers

Large fibers that conduct impulses to ventricular myocardium; conduct impulses to apex first; whorled pattern of muscle in ventricles contract with twisting motion

•Physical exercise •Body temperature •Fight-or-flight response •Concentration of various ions, such as K+ and Ca+2

SA node (pacemaker) normally controls the heart rate, and heart rate changes occur due to factors that influence the SA node Sympathetic and parasympathetic fibers modify the heart rate in response to changing conditions, such as:

structure of the heart

Size and location of heart: •Size of fist, varies with body size, averages 14 cm long, 9 cm wide •Located inside thoracic cavity, in mediastinum, behind sternum, above diaphragm, near lungs •Broad base lies beneath the 2nd rib •Pointed apex lies at the 5th intercostal space •Hollow, cone-shaped organ, containing double pump •Divided into left and right halves

1. right, 2. left 3. left, 4. right

organization of the heart: - ___1___ side pumps to pulmonary circuit, blood return to ____2___ side - ___3___ side pumps to systemic circuit, blood returns to __4__ side

tunica externa

outer layer of arteries, connective tissue

epicardium

outer layer of heart, thin; also called visceral pericardium; reduces friction; Serous membrane of connective tissue covered with epithelium and includes blood and lymph capillaries and nerve fibers; adipose tissue around large blood vessels of the heart; Forms a protective outer covering; secretes serous fluid

SA (sinoatrial) node

pacemaker; initiates rhythmic contractions of the heart

SA node → atrial syncytium → junctional fibers → AV node → AV bundle → bundle branches →purkinje fibers → ventricular syncytium

path of a cardiac impulse

two closed circuits

______ _____ _____ are included in cardiovascular system which are pulmonary and systemic circuit

cardiac center

_______ _____ in medulla oblongata performs neural regulation of heart

blood flow distribution to capillaries

_____________________ can change with situation: •During exercise, muscle capillaries receive more blood flow, and digestive system capillaries receive less •After a meal, digestive system capillaries receive more blood flow, and muscles receive less

heart sounds

a heartbeat through a stethoscope sounds like "lubb-dupp"; sounds are due to closing of heart valves and vibrations associated with a sudden slowing of blood flow during contraction/ relaxation of chambers

chord tendineae

are fibrous strings that attach cusps of tricuspid and mitral valves to papillary muscles in wall of heart

circumflex branch

supplies left atrium and ventricle

posterior interventricular artery

supplies posterior ventricles

right marginal branch

supplies right atrium and ventricle

anterior interventricular (left anterior descending) artery

supplies walls of ventricles

P wave, QRD complex, T wave

the deflection in the normal ECG, or waves include

chambers

the heart ______ function in regulated, coordinated manner

ventricles

thick walled lower chambers; pump blood into arteries

fibrous pericardium

tough outer layer that surrounds double layered serous membrane

arteries

transport blood away from the heart

capillaries

transport blood between arteries and veins, and perform nutrient, gas, and waste exchange

blood vessels

transport blood throughout the body

veins

transport blood toward the heart

systemic circuit

transports oxygen rich blood and nutrients to body cells, removes wastes from cells, flows back to heart

QRS complex (3 waves)

ventricular depolarization; occurs just prior to ventricular contraction

T wave

ventricular repolarization; occurs just prior to ventricular relaxation

cardiac cycle

•(the events that occur during a heartbeat): •Atria contract (atrial systole) while ventricles relax (ventricular diastole) •Then ventricles contract (ventricular systole) while atria relax (atrial diastole) •Then both chambers relax briefly

electrocardiogram (ECG, EKG)

•A recording of electrical changes that occur in the myocardium during the cardiac cycle •Used to assess ability of heart to conduct impulses

greater

•At venular end of capillary, H2O is reabsorbed into capillary because colloid osmotic pressure is _______ than hydrostatic pressure

during atrial systole and ventricular diastole

•Atria contract and ventricles are relaxed •The AV valves open and the semilunar valves close •Atrial systole pushes remaining 30% of blood into the ventricles, causing ventricular pressure to increase

example of baroreceptor reflex response

•Baroreceptors in aortic arch and carotid artery sinuses detect blood pressure •Increased pressure stretches receptors •Parasympathetic cardioinhibitory reflex lowers heart rate and blood pressure

AV (atrioventricular) bundle (of His)

•Conducts impulses rapidly between SA node and bundle branches

characteristics of cardiac muscle cells

•Have 1 central nucleus, and form branching networks •Intercalated discs between cells contain desmosomes for structural support, and gap junctions to spread action potentials through a network of cells •Form a functional syncytium, mass of merging cells that function as a unit: 2 such masses exist in the heart: •In the atrial walls; called the atrial syncytium •In the ventricular walls; called the ventricular syncytium

baroreceptor reflexes

•Involve cardiac control center in medulla oblongata •Balance inhibitory and excitatory effects of parasympathetic and sympathetic fibers •Contains a cardioinhibitor reflex center and a cardioaccelerator reflex center

transcytosis

•Large substances (antibodies and lipoproteins) use this method •Substances enter endothelial cell by endocytosis, and leave other side of cell by exocytosis

diffusion

•Most important method of transfer •Lipid-soluble substances diffuse through cell membrane; water-soluble substances diffuse through membrane channels and slits

osmosis

•Presence of impermeant solute, such as plasma proteins, inside capillaries creates osmotic pressure •Osmotic pressure draws water into capillaries, opposing filtration •Colloid osmotic pressure refers to pressure due to plasma proteins •At arteriolar end of capillary, H2O and other substances leave capillary by filtration because hydrostatic pressure > colloid osmotic pressure •At venular end of capillary, H2O is reabsorbed into capillary because colloid osmotic pressure > hydrostatic pressure •More fluid leaves capillaries at arteriolar end than returns at venous end •Lymphatic vessels return excess fluid through the lymphatic system to the venous blood

sympathetic impulses that innervate heart

•Reach heart on accelerator nerves •Increase heart rate, due to influence on SA and AV nodes, atrial and ventricular myocardium

parasympathetic impulses that innervate heart

•Reach heart via vagus nerves •Lower SA node rate of 100 beats/min to 60 to 80 beats/min •Decrease heart rate, due to influence on SA and AV nodes

larger

•Record of atrial repolarization is "hidden" in the large QRS complex, since ventricular depolarization is a much ______ event

capillaries

•Smallest-diameter blood vessels •Connect the smallest arterioles and the smallest venules •Extensions of the inner lining of arterioles •Walls consist of endothelium (simple squamous epithelium) only •Semipermeable; exchange substances between blood and tissue fluid •________ blood flow regulated mainly by precapillary sphincters: smooth muscle surrounding capillary when it branches off arteriole or metarteriole

left and right bundle branches

•Split off from AV bundle, conduct impulses to Purkinje fibers on both sides of heart

early in ventricular diastole

•Ventricular pressure is lower than atrial pressure •Atria and ventricles are relaxed •AV valves open, and semilunar valves are closed •About 70% of blood flows passively from atria into ventricles

during ventricular systole and atrial diastole

•When ventricular pressure rises above atrial pressure, AV valves close •Chordae tendineae prevent the cusps of the valves from bulging too far backward into the atria •Atria relax •Blood flows into atria from venae cavae and pulmonary veins •Ventricular pressure continues to increase, and opens the semilunar valves •Blood flows into the pulmonary trunk and aorta