The Heart
Location: thoracic cavity, between lungs, size of clenched
fist, 2/3rds on left side of sternum
Pericardium: double layered serous membrane
Outer layer: parietal pericardium, pericardial sac
Inner layer: visceral pericardium or epicardium
Pericardial cavity: fluid filled space between the
pericardial layers
Heart Chambers
Atria: receiving chambers for blood
Right atria: incoming blood from superior vena cava
Drains blood from superior portions of body
And inferior vena cava/ blood from regions
below the heart
Coronary sinus: drains blood from heart wall
UNOXYGENATED
Ventricles: provide the force to push blood out of the heart
Myocardium much thicker in ventricles than atria
Forcefull contractions
Right ventricle : pulmonary trunk then to lungs
Left ventricle : into aorta which branches
Oxygenated blood to body
Valves of heart: permit blood to move in one direction
Atrioventicular valves: 2 to 3 flaps(cusps), point
down, located between atria and ventricles
Tricuspid valve: between right atria and ventricle
Bicuspid valve: between left atria and ventricle(mitral
valve)
Heart murmur: if valves aren’t anchored properly to
muscular wall of ventricle(chordae tendinae)
Blood re -enters atrium when ventricle contracts
Semilunar valves: located between ventricles and vessels
carrying blood away from heart(shaped like 3 half moon
bowls, convex side facing ventricle)
Pulmonary valve: right ventricle to pulmonary trunk
Aortic valve: from left ventricle to aorta
Blood flow through heart:
Unoxygenated blood from superior and inferior vena cavae,
coronary sinus to RIGHT ATRIUM - tricuspid valve –
RIGHT VENTRICLE – pulmonary valve – to Pulmonary
Trunk – pulmonary arteries -LUNGS – OXYGEN Pulmonary veins(4) – LEFT ATRIUM –mitral valve –
LEFT VENTRICLE – aortic valve –AORTA to all
body(except lungs)
Anatomy of Heart Tissue
Location: thoracic cavity, between lungs, size of clenched
fist, 2/3rds on left side of sternum
Pericardium: double layered serous membrane
Outer layer: parietal pericardium, pericardial sac
Inner layer: visceral pericardium or epicardium
Pericardial cavity: fluid filled space between the
pericardial layers
Pericardial cavity: between epicardium and serous layer
Filled with serous fluid
Pericarditis: pericardium becomes infected
Fluid production stops
Increase friction
Decrease heart function
Heart Wall:
Epicardium: serous membrane
Fat deposits along channels of BV which
Provide oxygen to heart wall
Myocardium: bulk of heart wall
Cardiac muscle cells : striated b/c of
Intercalated discs
Points of attachment between cardiac
Muscle cells – facilitates
conduction, so that all cells function together
Contracts to propel blood
Bundles of cells interwoven with CT
CT= “fibrous skeleton
Endocardium(endothelium)
Smooth white membrane
Lines heart chambers and is continuous into
BV and heart valves
Heart Chambers
Heart Chambers:
2 thin walled atria = receiving chambers
2 thick walled ventricles = pumping chambers
Left wall is thicker than R wall(WHY?)
Atria: very little myocardium
External structure = auricle(little ears)
Help to increase volume of atria
Underlying endocardium = pectinate muscles
Resemble teeth of comb
Interatrial septum: separates both atria
Posterior wall = fossa ovalis = remnant
Of foramen ovale= hole in septum
To allow fetal blood to bypass lungs
Right Atrium: incoming blood(unoxygenated)
3 sources: superior vena cava
Inferior vena cava
Coronary sinus
Left Atrium: collects blood from 4 pulmonary veins
From lungs(oxygenated)
Ventricles: inner walls – trabeculae carnae (ridges of
muscles) and Papillary muscles(individual cones) which
assist valves – “tug on heart strings” once these muscles
contract they “tug” on chordae tendonae which open the
valves
Interventricular septum: separates ventricles
Interventricular sulcus: exterior groove
Coronary sulcus: exterior groove separates
Atria from ventricles
Both grooves lines with fat and BV
Pectinate muscles: Atria:: Trabeculae carnae: ventricle
Right atria
Receives blood
From body
Left Atria
receives blood
from lungs(PV)
Right Ventricle
Sends blood
To lungs
Pulmonary trunk to
LPA and RPA
Left Ventricle
sends blood to body
Aorta
Blood Pressure: The force exerted by blood against the
interior walls of the BV
Highest in arteries and arterioles
Negligible in veins, venules, and capillaries
Skeletal muscle, valves, and respiratory
Activity moves blood back to heart
Arterial Blood Pressure:
Arterial Blood Pressure:
Pressure gradient: move from high P to low P
Systolic Pressure: (120mg) (contraction)
From heart to Aorta
Elastic walls of aorta
Diastolic Pressure: (relaxation) (70-80mg)
Beyond the junction of heart and aorta
Sphygmomanometer: measures bp
Brachial artery compressed
Release valve on cuff allows blood to flow
through brachial artery
Stethoscope picks up tapping sound as blood
moves back through Brachial artery
(systolic pressure)
Once the tapping becomes inaudible (diastolic Pressure)
Regulation of BP
Factors that control BP: nervous system, endocrine
system, kidney function
Nervous system: Medulla oblongata – vasomotor center
Supplies the nerves that innervate smooth muscle of
arterioles to control vasoconstriction or dilation
Receives info from baroreceptors in aorta and carotid
arteries – also chemoreceptors send info on oxygen content
and pH levels
Endocrine system: epinephrine and norepinephrine
Secreted during stress
From adrenal medulla(above kidneys)
Epinephrine – increases cardiac output
Norepinephrine – increases peripheral resistance
Antidiuretic hormone: hypothalamus
Stimulates kidneys to conserve water(increase
Blood Volume, ie, blood pressure)
Atrial natriuretic factor: secreted by atria
Reduces Blood volume
Stimulates kidneys to excrete Na+ and water
Kidney Control:
Arterial blood pressure drops – kidney cells secrete
RENIN- Renin triggers AGIOTENSIN II a vasoconstrictor
Triggers ALDOSTERONE produced by adrenal
gland(above kidney) causes Na+ to be reabsorbed by blood
– results in water also moving into BV, increases Blood
Pressure
Factors that INFLUENCE BP:
(1) Cardiac output: heart rate and stroke volume
(2) Blood Volume: Plasma volume and hematocrit
(3) Peripheral resistance: BV diameter and viscosity
1,2,3 determine blood pressure which influences Blood
Flow
Work together to ensure proper blood volume