CV Final Flashcards
Arterioles have the greatest what?
resistance to bloodflow
Vein function?
Capacitance function (blood volume)
Distension of the aorta and its branches during?
Systole
• Elastic recoil of the large arteries with forward propulsion of blood during ventricular relaxation during?
Diastole
Velocity of blood flow is __________ related to the cross-sectional area of the vascular system
Inversely.
Blood flow velocity is very slow in the capillaries
The cardiac output is controlled mainly by the sum of?
all the local tissue flows
Cardiac accelerators
Sympathetic
T1-T4
Stellate ganglia (cervicothoracic ganglia) and middle cervical ganglia
Parasympathetic
– Much innervation to SA and AV nodes
– Little innervation to ventricles
Pericardium Layers
– Fibrous
– Serous
• Parietal layer
• Visceral layer
Potassium is the major determinant of the _________ ________ _______
Resting Membrane Potential
As K+ leaves cell, ________ increases on the inside of the cell membrane and __________ attracts K+
negativity, electrostatically
Na+, K+ - ATPase Pump Ratio
Pumps in 3:2 ratio (3 Na+ out: 2 K+ in)
PHASES OF THE FAST RESPONSE ACTION POTENTIAL
- Phase 0 = Depolarization
- Phase 1 = Partial Repolarization
- Phase 2 = Plateau
- Phase 3 = Repolarization
- Phase 4 = Resting Membrane Potential
ERP & RRP
ERP = Effective Refractory Period (cannot regenerate another action potential)
RRP = Relative Refractory Period (can begin to generate another action potential)
Phase 0
• The characteristics of the upstroke of the action potential depend almost entirely on inward movement of Na+
There is a small inward Ca++ current (important for contraction)
PHASE 1 – Partial Repolarization
Inactivation of Na+ channels ends
Transient outward K+ current
PHASE 2 - Plateau
What produces the plateau?
Slow inward Ca++ currents (L-type calcium channels)
Counterbalanced by:
Outward K+ currents
PHASE 3 - Repolarization
What outward movement is mainly responsible for repolarization?
K+
Na+ channel recovery begins during Relative Refractory Period
PHASE 4 – Resting Membrane Potential
- Restoration of ionic concentrations
- Na+,K+-ATPase
- Na+-Ca++ Exchanger (driven by gradients not electrical)
- ATP-driven Ca++ Pump
• The ability of a focal area of the heart to generate pace making stimuli is known as?
Automaticity
Calcium-Induced Calcium Release (CICR)
Because the T-tubules are continuous with the extracellular fluid, extracellular concentration of calcium becomes important for adequate heart contraction.
8 ECG Waves Intervals & Segments
Page 8
Ventricular Systole Phases
– Phase 2
Isovolumic contraction
– Phase 3 Rapid ejection (70% of ventricular volume is ejected)
– Phase 4
Reduced ejection
• Ventricular Diastole Phases
– Phase 5 Isovolumic relaxation
– Phase 6
Rapid filling
– Phase 7
Diastasis
– Phase 1
Atrial systole
Determinants of CO
Heart Rate
Contractility
Preload
Afterload
• Changes in heart rate alone inversely affect?
Stroke Volume
Effects of Heart Rate on Cardiac Output
Bowditch (Treppe) Effect
- An increase in heart rate will also cause positive inotropy (Bowditch effect, Treppe or “staircase” phenomenon).
- This is due to an increase in intracellular Ca++ with a higher heart rate
• Preload can be defined as?
the initial stretching of the cardiac myocytes prior to contraction. It is related to the sarcomere length at the end of diastole.
indirect indices of preload?
– LVEDV (left ventricular end-diastolic volume)
– LVEDP (left ventricular end-diastolic pressure)
– PCWP (pulmonary capillary wedge pressure)
– CVP (central venous pressure)
What is the Frank Starling Mechanism
The heart pumps the blood that is returned to it
Increasing venous return and ventricular preload leads to an increase in stroke volume.
What is afterload?
the “load” that the heart must eject blood against.
Afterload increased by?
Increased aortic pressure
Increased systemic vascular resistance
Aortic valve stenosis
Ventricular dilation
La Place and Afterload
– LaPlace’s Law: Wall stress = Pr/h
P = ventricular pressure
R = ventricular radius
h = wall thickness
What affects the FSC the most?
Changes in afterload and inotropy