Physio lecture 1 Flashcards
(35 cards)
3 principle components of CV system
Func impacted by
Heart (pump)
Blood vessels/vascular system (tubes)
Blood (fluid connective tissue)
CV func impacted by endocrine, nervous and urinary systems
Blood formed of
cells and cell fragments in liquid called plasma
erythrocytes
leukocytes
platelets
What is hematocrit
% of blood volume that is erythrocytes
RBCs func
contain?
shape?
Func: gas transport!
contain large amounts of hemoglobin
Biconcave shape -high surface area for improved diffusion
Platelets
contain?
produced when?
role in?
-Circulating, colorless, non-nucleated fragments that contain granules-smaller than RBCs
-produced when large bone marrow cells (megakaryocytes) pinch off into circulation
-role in clotting
Blood vessels
arteries and veins do what
exception to rule?
Arteries carry blood away from heart (oxygenated)
veins carry to the heart (deoxygen)
except:
Pulmonary arteries- carry deoxy blood to lungs to get oxygen.
Pulmonary veins-carry oxygen blood to heart to get delivered to body
Pressure
what is it
blood flows from..
-force exerted by blood -measured in Hg
High pressure area to low pressure area
Flow
what is it
-volume of blood moved per unit time (velocity)
ml/min
Resistance
what is it
-describes how difficult for blood to flow between two points at any given pressure difference
measure of friction that impedes flow
Resistance
factors that determine it
-blood viscosity
-total vessel length
-radius of vessel (radii of vessels is NOT constant- determines changes in resistance)
Epicardium
what kind of tissue
fibrous outer layer
Myocardium
composed of?
acts as?
middle layer
cardiac muscle
contractile layer
Endocardium
continuous with?
inner layer
continuous with lining of blood vessels entering and leaving heart
Atria
L and R what they receive from where
R atrium gets deoxy blood from systemic and coronary circulations
L atrium gets oxyg blood from pulmonary circulation
Ventricles
whole shabang
R ventricle pumps deoxy blood to lungs
L ventricle pumps oxy blood to rest of body including myocardium
R and L sides of heart- which circuit is which
Right-Pulmonary circuit
Left-Systemic circuit
Valves
2 AV- open in diastole (tricuspid and mitral)
2 semilunar- open in systole (pulmonic and aortic)
S1 (lub)-closure AV valves
s2 (dub)-closure semilunar
Coronary arteries
supply
max when
-supply oxygenated blood to myocardium
-max in diastole and min in systole
Left CA also has LAD(widowmaker)
Right CA
Cardiac veins
do what
coronary sinus
-drain deoxy. blood from myocardium
-runs parallel to arteries
-CS- collects blood from veins and returns to R atrium
Innervation
Para
Symp
Para- vagus nerve -decreases HR and force of contraction
Symp- cardiac splanchnic nerves- increases HR and force of contraction
Visceral afferent pain fibers follow symp pathways to T1-4 (referred chest pain from MI)
Other visceral afferents (stretch, baroreflexes, chemoreflexes) conveyed to brainstem via vagus nerve
Cardiac muscles
-arranged in tight layers that circle chambers
-every heart cell contracts with every beat of the heart
-LIMITED healing ability
Cardiac communication
-1% of cells do not contract, instead excite
-Conducting system is in electrical contact with muscle via gap junctions
-this system INITITIATES heartbeat and spreads AP through heart
Conducting system sequence
- SA node-pacemaker, initiates HB, altered by ANS
- AV node -receives pulses from SA and passes to bundle of His
- Bundle of His- transmits impulses to IV septum-> Purkinje fibers to distribute impulse to ventricular muscle
Nodal cells APs
SA- NO steady resting potential, undergoes slow depolarization called -Pacemaker potential
—AUTOMATICITY!!!!
Other cells slower, they are driven to threshold by APs from SA
Faster conduction wins!
