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The Cardiovascular System Jessica Dorantes Period 2, ., ., ., .…
The Cardiovascular System
Jessica Dorantes Period 2
Blood Vessels: blood delivery system that starts + ends at the heart.
Blood Flow
: blood volume through a vessel,
organ, or full circulation given in a period.
Structure of Blood Vessels
All blood vessels have a
lumen
...
central space surrounded by a wall.
All have 3 wall
layers / turnics
(except capillaries)
1) Tunica intima
: innermost layer,
simple squamous epithelium lines lumen
& decreases friction.
Subendothelial layer:
CT basement membrane
epithelium (vessel 1mm>)
2) Tunica media
: smooth muscle
with elastin sheets & sympathetic
muscle fibers allow:
Vasolidation
: increases lumen diameter
Vasoconstriction
: increases lumen diameter
3) Tunica externa:
aka tunica adventitia!
reinforcing + protecting wall,
anchors to surrounding tissue,
made up of loose collagen fibers &
has nerve fibers + lymphatic structures.
Vascular System
Systemic Arteries
run deep within body
Systemic Veins
run deep & superficial
deep veins share names w/
corresponding artery..
superficial veins don't..
Arteries
: carry blood away from heart!
It'soxgenated except through Purlmonary circulation.
Elastic arteries
: thick-walled, low-resistance lumen... expands & recoils as blood is ejected from heart.
Muscular arteries
: distributing arteries...
deliver blood to organs
Arterioles
: small + lead to capillary beds... aka resistance arteries bc diameter changes in resistance to blood flow.
Veins
: carry blood towards heart,
oxygenated except through pulmonary circuit
CLINICAL
: varicose veins;
dilated + leaky valves
Contributing factors:
inherited, prolonged
standing, obesity, pregnancy, or elevated
venous pressure (streining during childbirth).
Veins that empty into
the right atrium
Superior Vena Cava
: returns blood from above diaphram region
Inferior Vena Cava:
returns blood from below the diaphram
Coronary Sinus
: returns from the coronary veins
Venules have endothelial lining = porous!
Let fluids & WBC's pass into tissues.
Formed when capillary beds merge at postcapillary venules!
Have
LOW BP
: so they need adaptation
to ensure blood return to heart
Venous valves
: prevent backflow in veins
Venous sinuses:
flattened veins w/ thin walls
Capillaries
: direct contact w/ tissue
cells (provide cellular needs)
function
: exchange gases, nutrients, water,
hormones, etc. w/ blood & interstitial fluid.
microscopic vessels
: only 1 RBC passes at a time!
Walls
: thin tunica intima only
Capillary Beds: interwoven capillary
network between arterioles + venules.
Found in mesenteries!
Vascular shunt:
channels that directly connects
arteriole w/ venule ~ BYPASSES capillaries.
Preapillary sphincter:
valve-regulating
blood flow into capillary bed.
The Heart
Function
Pulmonary Circuit
: RIGHT side receives O2 poor blood from the body, pumps it to the lungs to get rid of CO2 & pick up O2
Systemic Circuit
: LEFT side receives O2 rich blood from the lungs and pumps out to the rest of the body
Microscopic Anatomy
Cardiac Muscle Cells
: striated, short, branched, interconnected, 1 central nucleus, lots of mitochondria.
Intercalated
discs
: connecting junctions between cardiac cells!
Blood Pathway
Coronary
CLINICAL
Angina Pectoris
: cells = weakened, thoraic pain is caused by decrease of blood deficiency to myocardium.
Myocardial infarction
(heart attack): prolonged coronary blockage... areas with dead cells are repaired with scar tissue.
Cardiac veins
: collect blood from capillary beds!
Coronary Sinus:
empties into right atrium...
formed by merging cardiac veins!
Great Coronary Vein
: anterior interventricular sulcus.
Middle Cardiac Vein
: posterior interventricular sulcus.
Small Cardiac Vein
: from inferior margin.
RIGHT SIDE:
from the vena cavas > right atrium > tricuspic AV valve > right ventricle > Pulmonary SL valve > purlmonary arteries > lungs (pulmonary ciscuit).
LEFT SIDE
: from the pumonary veins > left atrium > bicuspic AV valve > left ventricle > aortic SL valve > aorta > body tissues (systemic circuit).
Gross Anatomy
Chambers
Internal features
2
atria
/receiving chambers:
thin walled, small
Right atria
: receives O2 poor blood from body
Left atria
: receives O2 rich blood from lungs
Autricles
: appendages that increase atrial volume
2
ventricles
/ releasing chambers:
thick, actual blood pumps of heart
RIGHT ventricle: pumps blood into pulmonary trunk
LEFT ventricle: pumps blood into aorta
Trabeculae Carnae
: irregular ridges on muscle inside ventricle walls
Papillary muscles
: project into ventricular cavity,
connect chordae to trabeculae
ChordaeTendineae
: attached to heart valves (white)
Interatial Space
Interventricular Septum
Surface features
Coronary Sulcus (atrioventricular groove)
Anterior interventricular septum
Posterior interventricular sulcus
Valves
Atrioventricular (AV) Valves
Tricuspic valve
(RAV): made of 3 cusps,
between right atria and right ventricle.
Bicuspic valve
(mitral, LAV): 2 cusps,
between left atrium & left ventricle.
Chordinae Tendinea
: anchors cusps to papillary
muscles so valve stays in position, prevents backflow.
Semilunar (SL) Valves
prevent backflow from arteries into ventricles.
Have 3 cusps, akak "half-moon"
Pulmonary SL
: between right ventricle & pulmonary trunk
Aortic SL
: between left ventricle & aorta.
Layers
Epicardium
: visceral layer of serous pericardium!
Myocardium
: circle/spiral of contractile muscle cells!
Endocardiu
m: innermost, continuous with Endothelial
lining of blood vessels... lines heart chambers!
Coverings
CLINICAL!
Pericarditis
: inflammation of pericardium... cardiac tamponade fluid goes into pericardial space. Heart pumping decreases.
Pericardium
: deep & serous double-walled
sack... surrounds heart
Parietal
layer lines internal surface!
Visceral
(epicardium) layer lines external surface!
Events of the heart
Electrical Events
Intrinsic Conduction System:
non-contractile (autorhythmic)
cell network that sets rhythm
CLINICAL! Defects in ICS.
Arrhythmia
: irregular heart rhythm
Fibrillation
: fast, irregular contractions, heart becomes
useless for pumping blood + no circulation + brain dead.
Excitation Sequence
2) Atrioventricular (AV) node
, at inferior interstitial septum
1) Sinoatrial node,
pacemaker of heart in right atria wall: generates impulse + transmits to AV node.
3) Atrioventricular (AV) bundle of his,
in superior interstitial septum.
4) Right & Left bundle branches
, 2 pathways of interstitial septum: carry impulse towards apex.
5) Subendocardial conducting network
: full pathway through interventricular septum towards apex & ventricular walls.
Electrocardiography
Electrocardiogram
: graphic recording
of heart's electrical activity.
Records all AP at a given time
by electrodes placed at many points
to measure voltage differences.
Features
P wave:
depolarization of SA node & atria.
QRS complex:
ventricular depolarization & atrial repolarization.
T wave:
ventricular repolarization.
P-R interva
l: beginning of atrial & ventricular excitation.
S-T segment
: entire ventricular myocardium depolarized.
Q-T interval
: beginning of ventricular depolarization
through ventricular repolarization.
Mechanical Events:
follow after electrical events
Heart Sounds
(lub-dub):
closing & opening of valves.
1st sound
: closing of AV valves @ start of ventricular systole
2nd sound
: closing of SL valves @ start of ventricular diastole.
CLINICAL!
Heart murmurs
; abnormal sounds
when blood hits obstructions.
incompetent/insufficient valve
: fails to close fully ~
allows backflow.. blood flow from ventricle to atrium
creates swishing sounds
stenotic valve
: fails to open fully ~
restricts flow.. blood is forced through narrow valve
causes high-putches or clicking sound
Pause
between sounds = heart relaxation
Cardiac Cycle
: blood flow
during 1 full heart beat.
Diastole
: heart relaxation period
Systole
: heart contraction period
Atrial systole + diastole is followed by
ventricular systole + diastole!
Pumping Regulation
CLINICAL
Tachycardia
: fast heart rate (>100/min)...
if persistent causes fibrillation
Bradycardia
: slow heart rate (<60/min)...
poor circulation in athletes but good for endurance training.
Cardiac Output
: amount of blood being
pumped by each ventricle per minute.
Homeostatic Imbalance!
Congestive heart failure (CHF),
not enough CO2 being circulated to supply to tissue needs.
Coronary atherosclerosis
: weak myocardium bc of fat
buildup in arteries: doesn't allow O2 delivery to cardiac cells.. heart becomes hypoxic & contracts inefficiently.
High blood pressure
: aortic pressure greater than 90mmHg: myocardium exerts unnecessary force... causes it to become weak (hypertrophy).
Multiple myocardial infarcts
: heart becomes weak bc contractile cells are replaced with scar tissue.
Dilated cardiomyopathy (DCM)
: ventricles stretch,
become flabby: myocardium deteriorates.
Stroke volume
: blood volume
being pumped out by 1
ventricle per heartbeat.
Size & Location
Size of a fist, < 1lb.
Found in
mediastinum
: 2nd rib & 5th intercostal space
Base
: leans toward right shoulder, widest part of heart.
Apex
: leans toward left hip, tip of heart
Blood
Function
Circulates in arteries and veins
Carries oxygen and carbon dioxide to and from organs
Also transports water, waste,
gases, nutrients, hormones, etc.
Defense tissue! Fights against foreign
particles and stops bleeding via blood clotting.
Types of Blood
genetically
inherited antigens
B
AB
O
A
RH Factor
If present:
(+)
If absent:
(-)
Universal Donors!
Blood
: O-
Plasma
: AB+
Contains
WBC
leukocytes
: fight foreign particles
RBC
erythrocytes
: carry O2 & remove CO2
Plasma
yellow liquid: 90% water, 10% protein
Platelets
bits of RBC's that make fragments
promote clotting & make bruises
Disorders
Sickle Cell
: misshapes RBC's + breaks
them down.. no oxygen is circulated
Thalassemia
: less oxygen-carrying RBC & shortage.
Anemia
: caused by kidney disease
& leads to unhealthy + weak RBC's
Hemophilia
: inability to form blood cloths.
Blood Transfiusions
Due to loss of blood, inability to make it,
or to prevent blood disorder complications
If wrong blood type during this.. blood
can cloth boos vessels = fatal!
Blood Pressure: force per unit area exerted by blood on a blood vessel wall.. measured in mmHg.
Systemic Blood Pressure
: highest in aorta, decreases through pathway ~ steepest drop @ arterioles.
Arterial Blood Pressure
Systolic Pressure
: exerted in aorta during ventricular contraction ~ (L)ventricle pumps into aorta + aorta stretches!
Diastolic Pressure
: lowest aortic
pressure level when heart's at rest.
Pulse
: arteries throbbing due to
different pulse pressures (felt on skin).
Monitoring
Circulation
Efficiency
Vital signs
: pulse, BP, respiratory rate, and body temperature.
Taking pulse!
Radial pulse
: @ wrist, most common
Pressure points
: arteries close to skin surface
(compressed to stop blood flow).
Measuring Arterial BP: indirectly measured by
AUSCULTATORY
methods,
sphygmomanometer
.
systolic
~ when sounds 1st occurs
when blood starts to spur through artery.
diastolic
~ when sounds are gone because
artery is no longer constricted (blood flows freely).
Venous Blood Pressure
: low pressure!
needs adaptation for venous return...
muscular pump
: skeletal muscle contracts
& "milks" blood back to the heart
respiratory pump
: pressure changes during
breathing make blood move towards heart by squeezing abdominal veins & expanding thoracic veins.
sympathetic vasoconstriction
: smooth muscle
constricts and pushes blood to heart.
Goal of BP
: be high enough so needed perfusion
to tissues occurs, but not too high it causes stroke.
Homeostatic Imbalances
in BP...
caused by posture, physical exertion,
emotions, fever, age, sex, weight, race.
Hypertension
: high pressure of 140/90mmHg... can lead to heart or renal failure, vascular disease, or stroke (myocardium working harder = weakens faster)
Hypotension
: low pressure < 90/60mmHg... only concerning if tissues don't receive enough blood ~ could mean long life or less cardiovascular illnesses!
Circulatory shock
: blood vessels fill up
and can't circulate blood properly.
Hypovolemic
shock
: too much blood loss.
Vascular shock
: too much vasolidation
and decreasing peripheral resistance.
Cardiogenic shock
: weak heart that
can't sustain good circulation.
Edma
: increasing amount of interstitial fluid due to increasing outward pressure (fluid out of capillaries) or decreasing inward pressure.
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