Exam 1 Flashcards
Major Functions of Cardio System
Transport
- Take in materials
- Move materials within the body
-Remove materials
Pulmonary Circuit
Arteries carry O2 poor blood to the lungs
Veins carry O2 rich blood to heart
Systemic Circuit
Arteries carry O2 rich blood to the body
Veins carry O2 poor blood to heart
Superficial to Deep Layers of the Heart
Fibrous Layer
Parietal Layer of Serous Pericardium
Pericardial Activity
Visceral Layer of Serous Pericardium (Epicardium)
Chordae Tendinae (explain what they are)
collagenous tendons that attach valves to walls of ventricles
Prevents valves from opening into the atria –> no backflow
Papillary Muscles
Anchoring Point for chordae tendinae which regulate tension of cords
Right Coronary Artery (what does it supply and branches of it)
Supplies the SA and AV node, parts of the right atrium, interventricular septum, and both ventricles
Marginal Branch: anterior right ventricle
Posterior IV Branch: posterior portions of both ventricles
Left Coronary Artery
Supplies SA node, left atrium, interventricular septum, and both ventricles
Circumflex Branch- left atrium and posterior left ventricle
Anterior Interventricular Branch- anterior portions of both ventricles
Important Cardiac Muscle Features
Intercalcated Disc Structure
- Interdigitating Folds: increase contact surface area between cells
- Mechanical Junctions: fascia adherenes act like Velcro to stick cells together–> Mechanical connection & desmosomes anchor cells together
Pacemaker Cells
1% of myocardial cells are specialized to generate action potentials (aka autorhytmic cells –> and not started by the nervous system)
Electrical Events Leading to a Heartbeat
-Initiated by pacemaker cells in SA node
- Spread via gap junctions and conducting network
Mechanical Events Leading to a Heartbeat
-Caused by electrical events
-Includes contraction (systole) and relaxation (diastole)
Pacemaker Potential Steps
- Slow influx of Na +
- # 1 + voltage gated Ca2+ channels open –> rapid depolarization
- Efflux of K+ –> repolarization
Electrical Signal Conduction
1) SA node fires
2) Excitation spreads through atrial myocardium
3) AV node fires
4) Excitation spreads down AV bundle
5) Subendocardial conducting network distributes excitation through ventricular myocardium
Key Difference between Cell Excitation in Cardio
Ca2+ signaling
Contractile Cell Excitation
- Voltage gated Na+ channels open
- Fast depolarization of membrane
- Closing of Na+ channels
- Opening of slow Ca2+ channels
- Ca2+ channels close and K+ channels open –> repolarization
P-Wave
AP generated in SA node –> atrial depolarization
PQ Segment
pause at AV node and conduction through septum
QRS Complex
ventricular depolarization + atrial repolarization
ST segment
corresponds to plateau of ventricular cardiomyocytes APs
T Wave
ventricular repolarization
TP Segment
period of rest and filling
Contractile Cell Contraction
myofilaments slide along each other –> shortened sarcomeres –> tension
Atrial Contraction
sarcomeres of contractile cells shorten –> tension –> decrease in atrial size (volume) –> increase of BP in atria –> blood moves into ventricles
Wiggers Diagram
Study!!
Heart Rate Regulation
Autonomic Regulation
- Cardiac Center in Medullar
- Normal HR = 60-100 bpm
- Parasympathetic
- slows heart rate (inhibitory)
- via vagus nerve
- targets SA and AV node
-Sympathetic
-Speeds up HR (excitatory)
-Targets SA and AV nodes, muscles, coronary arteries
Study HR Regulation Processes
:)
2 ways to speed up HR
- Block parasympathetic branch
- Increase sympathetic input
3 Influencing Factors for Stroke Volume
- Preload - degree of stretch (EDV)
- Contractility - contractile strength at a given length (ESV)
- Afterload - pressure overcome to eject blood (ESV)
Frank Starling Mechanism
STUDY!!
Pre-Load (main points abt it)
Degree of cardiac muscle sarcomere stretch
-Increased preload –> Increased SV
-Cardiac muscle sarcomeres normally at less-than-optimal length
- Stretching –> Optimal Sarcomere length–> Increased ability to generate force
BIGGEST FACTOR = VENOUS RETURN
Contractility
Contractile strength for a given preload
If more Ca2+ enters cardiac muscle –> more crossbridge formation –> stronger contraction –> more blood ejected from heart
Afterload
Pressure need to overcome in order to eject blood
hypertension –> reduces ability of ventricles to eject blood –> increase in ESV
Factors that Affect Cardiac Output
Hypocalcemia, Hypercalcemia, Hypernatremia, Hyperkalemia
Elastic Arteries (features and examples)
AKA Conducting
Thick-walled, near heart
Large lumen, lots of elastin
EX: Aorta, Carotid
Muscular Arteries
AKA Distributing
Most named arteries
Lots of smooth muscle
EX: Brachial, femoral
Resistance Arteries
Includes arterioles
Mostly smooth muscle
Major site of regulation
Capillaries
One cell layer thick
Simple endothelium
Site of exchange between blood and ISF
Capillary Beds (Perfusion and Vascular Shunt)
Perfusion: movement of blood into a capillary bed
-Arteriole –> capillary –> venule
Vascular Shunt:
- Bypass to skip capillary bed
-Metarteriole + thoroughfare channel
How are Capillary Beds Regulated
Upstream Arterioles - blood never reaches capillary bed
Precapillary Sphincters: single smooth muscle cells + close off individual capillaries from metarteriole –> vascular shunt
Capillary Exchange (what is dropped off and picked up)
Dropped Off: O2, glucose, nutrients, antibodies, hormones, etc.
Picked Up: CO2 and metabolic wastes, glucose & nutrients (adipose tissue, liver & digestive system) anitbodies, hormones
4 Major Mechanisms of Movements
Diffusion
Transcytosis
Filtration
Reabsorption
Major Routes of Capillary Exchange
Through endothelial cell layer
Through spaces between endothelial cells
Through filtration pores
Capillary Exchange - Diffusion General Properties
Passive transport
Move from high concentration to low concentration
Move until equilibrium
Fast over short distances, slow over long ones
Can happen in open or closed systems
Diffusion
Specific to capillaries
Through endothelial cell membrane, intercellular clefts, or filtration pores
Transcytosis
Infrequent mode of transport
Move very large molecules
Enodcytosis + vesicular transport + exocytosis
Filtration and Reabsorption
Physical pressure forces fluid through the membrane
Re-enters microcirculation on venous side due to pressure changes
Postcapillary Venules
Convergence of capillaries
Still porous
Muscular Venules
Add one or two layers of muscle
Up to 1 mm in diameter
Medium Veins
Most named veins
Distal veins often have valves
1-10 mm in diameter
Venous Sinuses
Thin walls, large lumens, no muscles
EX: dural sinuses in brain
Large Veins
3 distinct layers, lots of muscle
Thinner walls and larger lumens than arteries
EX: Venage Cavae, Pulmonary Veins
>10 mm in diameter
Simple Circulation Diagram
BE ABLE TO DRAW
Blood Flow and Pressure
Be able to describe basics
What happens when ventricular pressure > aortic pressure
Ejection of blood from ventricles to aorta
Aortic pressure increases then quickly decreases as blood moves out into systemic circulation
