Cardiovascular system: heart

cardiovascular system

trasnports blood throughout the body

• allows exchanges between capillary blood and body cells

perfusion

delivery of blood per time per gram of tissue

• mL/min/g

contains

arteries - oxygenated

veins - deoxinated

capillaries - exchange

what is the role of the right atrium

reveives deoxygenated blood from the body and pumps it to the lungs

Left ventricle

the role of the left ventricle s to pump oxygenated blood to the entire body

aortic semilunar valve

to stop the backflow of blood back into the left venticle

pulmonary trunk

carry oxugen from the right venticle to the lungs

what can cause unadequate perfusion and what would be the result of this

left and right heart failure, clots, plaque build up, failure of oxygne getting to the body

what is the mediastinum

seperates the heart from the lungs

where around the heart is serous fluid

pericardium

what is the inner layer of the ehart wall and what is its function

endocardium

• covers internal sufrace of heart and external sufrace of valves

• continous with lining of blood vessels

which type of heart valve is associated with tendinous cord? what is the function of the tendinous cord?

• attached to AV valves

• function of holds them to muscle, prevents them from flipping inside out

Two sides

• right side: reveives dexoygenated blood from the body and pumps it to the lungs

• left side: receives oxygenated blood from the lings and pumps it to the body

Great vessels

largest arteries and veins that are directly attached to heart

• arteires = away

  • pulmonary trunk transports from right ventricle

  • aorta transports from left venticle

• veins = towards

  • venae cavae (SVC and IVC) drain into right atrium

  • pulmonary viens drain into left atrium

valves

heart valves prevent backflow to ensure one-way blood flow

• atrioventircual (AV) valves are beween atrium and venticle

• semilunar valves are between a venticle and a arterial trunk

pulmonary circulation

• carries deoxygenated blood from right side of heart to lungs

• at lungs blood picks up oxygen and releases carbond dioxide

• returnes blood to left side of heart

Systemic circulation

majority of the systems

• moves oxygenated blood from left side of heart to systemic cells

• at systemic cells blood-exchanges gases, nutrients, and wastes

basic routes of circulation

right heart → lungs → left heart → systemic tissues → right heart

blood flow through pulmonary ciculation

1. deoxygenated blood enters the right atrium from the venae cave (SVC adn IVC) and then coronary sinus

2. this blood then passes through the right AV valve (tricuspid)

3. enters the right ventricular

4. passes through th epulmonary semilunar valve and

5. enters the pulmonary trunk

6. this blood continues throguh the right and left pulmonary arteries to both lungs and

7. enters pulmonary cappillaries of both lungs for has exchange

8. this blood which is now oxygenated, enters right and left pulmonary veins and is retured to

9. the left artium of the heart

Blood flow through systemic circulation

1. oxygenated blood enters the left atrium

2. passes through the left AV valve (bicuspid or mitril)

3. enters the left venticle

4. passes through aortic semilunar valve and

5. enters the aorta'

6. this blood is distributed by the systemic arteries and

7. enters systemic capillaries for nutirients and gas exchange

8. this blood, which is now deoxygenated ultimately drains into the SVC< IVC, and coronary sinus

9. enter left atrium

location and position of the heart

heart is enclosed in pericardium within thoracic cavity

• left of body midline

• seperated from lungs by mediastinum

• base - posterior-superior surface

• apex - inferior, concical end

pericardium:

three layered fibrouserous sac around the heart

1. fibrous, pericardiam → outermost layer, anchors heart and prevents it overfilling

2. pariatal layer of serous pericardium → middle, attaches to fibrous pericardium

3. visceral layer of serious pericardium → attaches direactly to heart

pericaridal cavity

space between serous membrane

external groves

sulci, marks borders of heart chambers

• coronary, interventicular (anterior and posterior)

grooves contain coronary vessels supplying blood to heart walls

Coronary sulcus

seperates atria from venticles

interventicular sulci

seperates left form right venticles

• anterior on anterior side

• posterior on posterior side r

anterior view

• right atrium and venticle appear prominent

• right auricle (wrikled extension of atrium is especially noticable)

• aorta and pulmoary trunk

posterior view

• left atrium and left venticle prominent

• left atrium forms base on posterior-superior surface

• pulmonary views attached to left atrium superior and inferior vena cava

• pulmoary artieres

heart wall variations

• venticles (pumps) have thicher walls that atria (receivers)

• left venticle has thicker wall then right venticle

epicardium

• deep to viseral layer of serous pericardium

• outermost heart layer

myocardium

• middle layter of heart wall (thickest)

• cardiac muscle tissue that contracts to pump blood

endocardium

• covers interal surface of heart and exteranl surface of valves

• continous with lining of blood vessels

Seperation of chambers

• interatrial septum seperates left and right atrium

• interventricular septum seperates left and right venticles

right atrium

• pectinate muscle → ridges on anterior wall and within atrium

• fossa ovalis → oval depression on interatrial septum

entrences

right atrium entrences

1. coronary sinus (carrying blodd from heart wall)

2. superior vena cava

3. inferior vena cava

exit to right venticle through AV valv

right venticle

• trabeculae carnea: irregular muscular ridges inside venticular wall

• papillary muscles: cone-shaped proections extending from interal venticle wall

• chordae tendineae (tendinous cords): heart stings

  • thin strands of collagen fibers attaching to AV valves

• superior exit to pumlonary trunk through pulmoary semilunar valve

left atrium

• has pectinate muscle in its auricle

• entrances from pulmonary veins

• exit to left venticle through left AV valve

left ventical

• trabeculea carnea on interal wall surface

• two papilarry muselce anchor chordea teninease

• superior exits to aorta to aortic semilunar valve

Ligamentum arterosium

• dense CT anchoring pulmonary trunk to aortic arch

atrioventricular valves

prevent backflow to atria

• when open, cups extend into venticles

• they close when venticles contract and push blood upward

  • papillary muscle and tendinous cords prevent flipping up into atria

semilunar valves

prevent backflow to venticles

• open when venticles contract and blood goes to arteries

• close when venticles relaz

  • arterial pressure becomes greater than venticular pressure

  • as blood starts to slide backward it catches cusps and closes valves

cardiac muscles

• short

• branched

• 1 - 2 nuclei

cardic muscle in depth

short, branched, one to two nucelu

• sarcolemma (plasma membrane)

  • invaginates to form T-tubules extending into cell

• sarcoplasmic reticulum

  • surrounds bundles of myofilaments

• myofiliments arranged in sarcomeres

metabolism of cardiac muscle

• high demand for energy

  • extensive blood supply

  • numerous mitcohondria

• able to use different types of fuel molecules

• relies mostly on aerobic cellular respiration metabolism

fibrous skeleton

• dense irregular connective tissue between the boundires of atria and venticles

• framework for msucle attachment

• electrical insulator

  • prevents venticles from contracting at same time as atria

spiral arrangement

• muscle cells are attached to fibrous skeleton and arranged in spiral bundles

• atrial contaction moves wall inward

• venticular contaction resemble wringing a mop

coronary circulation

deleives blood to heart walls

• coronary arteries - oxugenated blood

• coronary veins - deoxygenated blood

right and left cronary artiers sit in coronary sulcus

• branches off of the ascending aorta

right branches of coronary arteries (RMP)

• right marginal artery

• posterior interventicular artery

left branches (LAC)

• anterior interventicular artery

• circumflex artery

coronary veins

several cardiac veins drain heart muscle

• great cardiac vein

• middle cardia vein

• small cardia vein

ultimatly drained into

• coronary sinus

returned to

• right atrium

coronary blood flow is intermitted with heart contractions

Conduction system

initiates and conducts electrical events to ensure prper timing of contractions

• specialized cardia muslce cells that have action potientials but do not contract

• controlled by the autonomic nercous system

Flow of condiction

Sinoatrical (SA) node initates heart beat (pacemaker) → atrioventicular (AV) node → Atrioventicular (AV) bundle → purkinje fibers

medulla oblongata

• contains cardioacceleratory and cardioinhibitory centers

• receives signals from baroreceptors (stretch) and chemorectpros (chemical) in cardiovascualr system

  • modfies heart activity - does not initate it

parasympathetic innervation

• starts at medulla cardioinhibitory center (CN X)

  • decreases heart rate

sympathetic innervation

• starts at medulla’s cardioacceleratory center (cardiac plexus)

  • increases heart rate

  • increases force of contraction

cardiac cells are arranged in what typf of patter? why?

arragned in a spiral so they can twist up and not jsut out

which coronary artery gives rise to the circumflex artery

left coronary artery

what two types of strucutres drain the heart muscle

vein and sinus

into what chamber is deoxygenated blood from the heart tissue retured

right atrium

which of the two autonomic nervous system divisions has an effect on the force of heart contraction

sympathetic nervouse

heart contraction involves two different events

• the conduction sustem intitates and propagates an action ptoeitnal from nodal cell

• cardiac muscle cell fire action potientals and contract

  • signal moves from atria to venticles

conduction system : nodal cell

1. initation, SA node iniates action ptoeintal

2. spread of action potential, an action potiental is propagated througout the atria and the conduction system

conduction: cardiac muscle

1. the action potiental, propagated across the sarcolemma of cardia muscle cells

2. muscle contraction, thin filaments slide past thick filaments and sarcomeres shorten withthin cardia muscle cells

Nodal cell

iniatate heart beat

• spontaneoulsy depolarize and generate action peotienatal

• these cells do not contract themselves

resting membrane potiental about -60 mV

• have Na+/K+ pumps, Ca2+ pump and leak channels

Electrical events at the SA node

1. reaching threshold → slow voltage-gated Na+ channels open, inflow of Na” changes membrane potiental from -60 mV to 40 mV

2. depolarization → fast voltage-gated Ca2+ channels open, inflow of Ca2+ changes membrane potiental from -40 mV to just above 0 mV

3. depolarization → fast voltage gated Ca channels close, voltage channels open allow K+ outflow. Membrane potiental returens to RMP -60 mV and K+ channels close

Calcium

in cardiac cells, calcium mediates firing and no outside signals is necessary

concentrations

banna in a pool of salty milk

outside: Na, Cl, Ca

inside: K

Spread of cation potiental

1. an action ptoeitnal is generated at the SA node, it spreads via gap junctions between cardiac muscle cells througout the atria to the AV node

2. the action potiental is delayed at the AV node before it passes to the AV bundle within the interventtricual septum

3. the AV bundle conducts the action ptoeitnal to the left and right bundle branches and then to the Purkinje fibers

4. the action potietnal is spread via gap junction between cardia muscle cells througoput the ventricles

Cardiac muscle at rest

RMP 90-

1. deporlarization → fast voltage-gated Na+ channels open and Na+ rapidly enters the cell, reversing the polarituy from negative to postive (-90 to +30). These channels then close

2. plateau → voltage-gated K+ channels open and K+ flows out of cardiac muscle cells. Slow voltage-gated Ca+ channels opena nd Ca+ enters the cell with no electrical change and the depolarized state is maintained

3. repolarization → volatage-gated Ca+ channels close, voltage-gated K+ channels remain open, and K+ moves out fo the cardiac muscle cell, and polarity is reversed from postive to negative (+30 to -90)

true or false: cells of the cardiac node initiate heart contraction by being the first to contract

false

deplarization of the nodal cell membrane begins with the entrance of what posivity charged molecule

Na+

By what means does the action potential spread through the atriums?Venticels?

atriums → gap junctions

ventical → gap junctions

between → AV bundle to purkinje fibers

descirbe the plateau phase of cardiac muscle cells and why it occurs

open two channels at the same time, both Ca+ K+, both postive charges so they cancel out, still squeezing, potassium stays open longer and why it repolarizes

EKG

measure direction of charge change across the surface of the skin

• skin electrodes detec signals of cardiac msucle cells

Waves and segments

• p wave

• QRS complex

• T wave

• P-Q segment

• S-T segement

• P-R interval

• Q-T interval

Waves

P wave - refelcts electrical changes of atrial depolarization orginiating in SA node

T wave - electrical change associated with venticular repoalization

QRS complex

• electrical changes associated with venticualr depolarization

• atria also simultaenoulsy repolarizing

segments

P-Q → assoicated with atrial cell plateau (atria are contracting)

S-T → associated with venticular plateau (venticles are contracting)

interval

P-R → time from beginning of P wave to beginning of QRS deflection

• from atrial deoilarization to beginning of venticualr depoalrization

• time to transmit action potential throughout entire conduction system

Q-T → time from beginning of QRS to end of T wave

• refelcts time of ventricualr action potentials

• length depends upon heart rate

cardiac cycle

all events in heart from the start of heart beat to start of next

• contraction - systole (increase pressure)

• diastole (decrease pressure)

Pressure

contraction increases pressure; relaation decrease it

• blood moves down it pressure gradient (high to low)

• valves ensure that flow is forward (closure prevents backflow)