Chapter 19 Flashcards
Pulmonary circuit
right side: carries blood to lungs for gas exchange and back to heart
systemic circuit
left side of heart: supplies oxygenated blood to all tissues of the boy and return it to the heart
left side of heart
- oxygenated blood
- enter via pulmonary veins
- leave via aorta
right side of heart
- oxygen-poor blood
- enter via inferior and superior venae cave
- leave via pulmonary trunk
Pericardium Function:
double walled (triple layered space around the heart)
- protects and anchors the heart
- prevents overfilling of the heart with blood
- allows for a relatively friction-free environment`
pericardial sac
outer wall made of two layers
- superficial fibrous layer of connective tissue
- deep serous layer parietal pericardium
visceral pericardium (epicardium)
serous membrane covering heart
The heart wall
Has three layers
epicardium
myocardium and endocardium
Epicardium
visceral pericardium
- serous membrane covering heart
- adipose in thick layer in some places
- coronary blood vessels travel through this layer
Endocardium
- smooth inner lining
- covers the valve surfaces and is continuous with endothelium of blood vessels
Myocardium
layer of cardiac muscle proportional to work load
-muscle spirals around the heart produces a wringing motion
which side of the hears has more muscle
left side
The chambers
atria and ventricles
Atria of heart
receiving chambers of the heart
left atria = receiving oxygenated blood
Atria of heart
each atrium has an auricle to enlarge chamber
Atria of heart muscle
pectinate muscles
-internal ridges of atria and auricles
Ventricle of the heart
discharging chambers of heart
ventricle of the heart muscle
trabecular carnae
-internal ridges in both ventricles
The valves ensure
one-way flow of blood
Atrioventricular (AV) Valves
control blood flow between atria and ventricles
Right AV
tricuspid valve
Left AV
Mitral valve
What do the cord tendineae prevent
AV valves from flipping or bulging into the atria when ventricles contract
Semilunar valves
located at exit of ventricles
Right semilunar valves
pulmonary semilunar valve
Left semilunar valves
aortic semilunar valve
Blood flow
Ventricles contract
- AV valves close as blood attempts to back up into the atria
- pressure rises inside of the ventricles
- semilunar valves open and blood flows into great vessels
Blood flow
Ventricles relax
- Pressure drops inside the ventricles
- semilunar valves close as blood attempts to back up into the ventricles from the vessels
- AV valves open
- blood flows from atria to ventricles
Blood flow starting with the right Atrium
Right atrium -> AV valve-> right ventricle -> pulmonary semilunar valve-> pulmonary trunk -> pulmonary arteries -> lungs -> pulmonary veins -> left atrium -> AV valve -> left ventricle -> aortic semilunar valve -> aorta -> systemic circulation.
cardiocytes
Striated, short thick, branched cells
-repairs of damage of cardiac muscle is almost entirely by fibrosis (scarring)
Intercalated dies contain
- desmoses
- Gap junctions
Metabolism of cardiac muscle depends almost exclusively on
aerobic respiration to make ATP
cardiac muscle are Rich in
myglobin and glycogen
huge mitochondria
The conduction system
what cells
Autorhythmic cells
Autorhythmic cells
composes internal pacemaker and nerve-lie conduction pathways through myocardium
Autorhythmic cells initiates…
and distributes action potential through the heart
Autorhythmmic cells lead to
depolarization and contraction of the rest of myocardium
Sinoatrial nodes
pacemaker
typically determines heart rate
Atrioventricular node
electrical gateway to the ventricles
Atrioventricular bundles (bundle of his)
Bundle forks into right and left bundle branches
purkinje fibers
nerve like processes spread throughout ventricular myocardium
-cardiocytes then pass signal from cell to cell throughout gap junctions
nerve supply to the heart
- sympathetic nerves
increase heart rate and contraction strength
nerve supply to the heart
- parasympathetic nerves
slow hear rate
systole
contraction
diastole
relaxation
sinus rhythm
normal heartbeat triggered by the SA node
Ectopic focus
any region firing other than the SA node
-may set hear rate if SA nod damaged
Nodal rhythm
if SA node is damaged, heart rate is set by the AV node 40-50 bpm
order of conduction system of the heart
Sinoatrial node -> Atrioventricular node -> Atrioventricular bundle ( bundle of his) -> bundle branches -> purkinje fibers
which structure in the conduction system is considered the pacemaker
sinoatrial node
in which structure of the conduction system does the impulse slow down
A-V node
why do you think the impulse needs to slow down here?
the atria and ventricle would contract at the same time and blood would not flow effectively
P-wave
atrial depolarization
atrial depolarization is normally obscured by the…
QRS complext
which wave is ventricular depolarization
QRS
Which wave is ventricular depolarization?
T-wave
Between which two waves will you have atrial contraction
P-Q
Between which two waves will you have ventricular contraction
S-T
Signals in the AV node slow down to
the delays allows the ventricles time to fill.
cardiocyte action potential has how many phases
three
what are the three phases of cardiocyte action potential
depolarization plateau and repolarization
Depolarization phase
very brief
- stimulates opens voltage-regulated Na+ gates ( sodium rushes in)
- sodium gates close quickly
Plateau phase
lets about 200 to 250 ms sustains contractions for expulsion of blood from heart
- voltage gated slow calcium channels open admitting calcium which triggers opening of calcium channels on sarcoplasmic reticulum
- calcium binds to troponin triggering contractions
depolarization phase
-calcium channels close, potassium channels open , rapid diffusion of potassium out of cell returns it to resting potential
resting membrane potential of skeletal muscle is (stable or unstable)
stable
what leads to action potential of skeletal muscle
requires motor neuron to release ACh and the binding of ACh causes depolarization of motor end plate which lead to action potential of skeletal muscle
resting membrane potential of cardiac muscles is ( stable or unstable)
unstable
Cardiac muscles have ( fast or slow ) depolarization to threshold
slow
cardiac muscles, at threshold, have ( fast or slow) depolarization
fast
SA node fires and atria depolarize at which wave
p-wave
Ventricular depolarization
QRS complex
corresponds to plateau in myocardial action potential
ST segment
ventricular depolarization and relaxation which wave
t-wave
when the ventricles are in diastole, are the A-V valves open or closed?
open
when the ventricles are in systole, are the A-V valves open or closed/
closed
When the ventricles are in diastole, are the semilunar valves open or closed?
closed
when the ventricles are in systole, are the semilunar valves open or closed?
open
phase of the cardiac cycles
- ) ventricular filling
- ) isovolumetric contraction
- ) ventricular ejection
- ) Isovolumetic relaxation
Ventricular filling
is during diastole
- ventricles relax and expand, pressure decreases
- blood flows from atria to ventricles
- atria contract to finish filling ventricles
- AV valves are open; semilunar valves are closed
isovolumetric contraction
ventricular systole
atria in diastole
ventricles are completely closed off (all valves closed_
ventricles ejection
ventricular systole
atria in diastole
AV valves close seminar valves forced open
isovolumetic relaxation
both atria and ventricles are relaxed; all valves closed
left ventricular failure
blood backs up into the legs causing pulmonary edema
— shortness of breath or sense of suffocation
right ventricular failure
blood backs up in the vena cava using systemic or generalized edema
proprioceptors
stretch receptors in muscle and joint
**are sensors that provide information about joint angle, muscle length, and muscle tension, which is integrated to give information about the position of the limb in space.
if the proprioceptors are activated, what does HR do
heart rate goes up
Baroreceptors
A baroreceptor is a specialized nerve ending that allows your brain to sense blood flow and blood pressure in the major blood vessels of your circulatory system.
if baroreceptor sense blood pressure increases what does HR do
wants to slow heart rate down
chemoreceptors
sensory extensions of the peripheral nervous system into blood vessels where they detect changes in chemical concentrations.
if chemoreceptors sense hypercapnia what does HR do?
increase heart rate
if chemoreceptors sense hypoxia
hypoxia slows hear rate down; slow heart rat tell brain to speed up heart rate.
preload
how much blood fits in the ventricles at its max
contractility
how hard the ventricles will contracts
Positive inotropic agents
increase contractility
hypercalcemia catecholamines glucagon digitalis
negative inotropic agents
reduce contractility
- hypocalcemia hyperkalemia
acidosis
drugs such as calcium channel blockers
Afterload
sum of all forces opposing ejection of blood from ventricles
**** higher the pressure is in the aorta then the ventricle have to work 2 times harder to push the valves open .
what increases afterload
hypertension increases after load and opposes ventricular ejection
** working harder but pumping out less blood so heart beats fast to accommodate for the little blood pumping
