Save
Human Anatomy and Physiology I
Week 27 - The Cardiovascular System
Save
Share
Learn
Content
Leaderboard
Learn
Created by
Daiyan Prodan Jahirul
Visit profile
Cards (15)
The cardiovascular system consists of:
A
muscular pump
(the
heart
)
A
series
of
tubes
(the
blood vessels
)
A
liquid
(the
blood
)
Functions of the cardiovascular system include:
Transport
of materials around the body (to and from all parts of the body)
Circulation
of oxygen, nutrients (glucose, fatty acids) & water
Removal of
waste products
(CO2, metabolic waste, heat)
Cell-cell
communication
(
hormones
)
Immune
defence
(White blood cells,
antibodies
)
Divisions of circulation:
Pulmonary circulation:
Right
side receives
blood
from
tissues
and sends it to
lungs
for
oxygenation
Systemic circulation:
Left
side receives newly
oxygenated blood
from
lungs
and pumps it to
tissues
Blood flows because liquids move from
high
to
low
pressure regions
Contraction of the heart creates pressure
without
changing the volume of blood
Pressure in ventricles is called
driving pressure
Hydrostatic
Pressure: exerted by a fluid which is not moving and force is exerted equally in all directions
Pressure
=
Force
/
Area
Flow
usually means flow rate, the
volume
of
blood
that passes a
given point
in the
system per unit
of
time
Velocity
of
flow
(or simply
velocity
), the
distance
a
fixed volume
of
blood travels
in a
given period
of
time
The
tendency
of the
cardiovascular system
to oppose blood flow is called Resistance
Velocity depends on the flow rate and the cross-sectional area
Factors affecting resistance to fluid flow:
Resistance increases
as the
length
of the
tube increases
Resistance increases
as the
viscosity
(
thickness
) of the
fluid increases
Resistance decreases
as the
tube's radius increases
A
decrease
in
blood vessel diameter
is known as
vasoconstriction
An increase in
blood vessel diameter
is called
vasodilation
The heart is divided by a
central wall
or
septum
Each half functions as an
independent pump
that consists of an
atrium
and a
ventricle
The two sides contract in a
coordinated
fashion
Atria receive
blood returning
to the heart, right from
tissues
, left from
lungs
Ventricles
pump
blood away
from the heart
Heart valves:
Atrioventricular
valves control blood flow between
atria
and
ventricles
Semilunar
valves control blood flow between the ventricles and the arteries
During
ventricular contraction
, the
semilunar
valves are
open
but the
atrioventricular
valves remain
closed
During
ventricular relaxation
, the
semilunar
valves prevent
blood
from flowing back into the ventricles
Cardiac muscle:
Contractile fibers are organized into
sarcomeres
Attached to each other by
intercalated discs
containing
desmosomes
and
gap junctions
Autorhythmic cells
signal for
contraction
and have no organized
sarcomeres
Action potential in cardiac myocytes is similar to
neurons
and
skeletal muscle
but
longer
Electrical conducting system of the heart:
Sinoatrial
(
SA
) Node acts as the main heart
pacemaker
Depolarization
wave spreads rapidly via
Internodal
pathways to
Atrioventricular
(
AV
) node
Purkinje
fibers conduct electrical signals rapidly down the
Atrioventricular
bundle/
Bundle of His
in the
ventricular septum
Electrocardiogram
(
ECG
):
Records electrical activity
of the
heart
Consists
of
waves
,
segments
, and
intervals
3
major waves on a
normal ECG
are
P wave
,
QRS complex
, and
T wave
Cardiac cycle:
Two main phases are
diastole
(
relaxation
) and
systole
(
contraction
)
Atria and
ventricles
do not
contract
and
relax
at the same time
Cardiac cycle begins with the
atria
and
ventricles
at
rest
Blood pressure:
Measured in
mm Hg
Blood flow through the heart is governed by
pressure
Fluid flows from
high
to
low
pressure
Cardiac cycle & the Pressure-Volume Graph:
Represents changes in
left ventricular pressure/volume
during
one cardiac cycle
Follows
left heart
&
aortic pressures
,
left ventricular volume
, & the
ECG
through
1 cardiac cycle
Gallops, Clicks, and Murmurs:
Gallops
are
additional
sounds recorded with very
sensitive
electronic stethoscopes or in certain
abnormal
conditions
Clicking sounds are made by
abnormal
movement of
valves
Murmurs
are "whoosh" sounds from
blood leaking
through incompletely closed or
stenotic
valves