Cardio 1 Flashcards
Cardiovascular system
- Cardiovascular = Cardio (heart) + vascular (blood vessels)
Role of CV system in body
- Delivers oxygen/nutrients to organs/tissues
- Removes waste (CO2, other cell respiration by-products) from organs/tissues
Size of heart
Size of person’s fist (correlated with size)
Shape of heart
blunt cone-shaped
Position of heart
Slightly sifted to left side
Location of heart
- Lies in mediastinum in thoracic cavity
- Sits on top of diaphragm
- Be hind sternum
- In front of vertebral column
- Between lungs
- Enclosed/protected by ribs
- Right/left sides separated by muscular septum
Epicardium
- Covers surface of heart + great vessels
- Also called: visceral pericardium
Myocardium
Muscular middle layer:
- Cardiac muscle cells: striated branching cells with many mitochondria, intercalated disks for synchronous contraction
- Cardiac myocytes: striated, branching cells with fibrous cardiac skeleton; coronary vessels
Endocardium
Innermost layer
- Made of thin epithelial layer, underlying connective tissues
- Lines heart chamber, valve
Pericardium
Double-layered sac surrounding heart
- Fibrous pericardium
- Serous pericardium
- Parietal pericardium
- Visceral pericardium (epicardium)
Fibrous pericardium
- Outer layer
- Touch fibrous connective tissue anchors heart within mediastinum
Serous pericardium
Simple squamous epithelial layer
Parietal pericardium
- Lines fibrous pericardium
- Secretes protein-rich fluid (pericardial fluid)
- Fills space between layers (lubricant for heart, prevents friction)
Visceral pericardium (epicardium)
- Covers outer surface of heart
- Secretes protein-rich fluid (pericardial fluid)
- Fills space between layers (lubricant for heart, prevents friction)
Atrioventricular valves
- Separate atria from ventricles
- Tricupsid and bicuspid
Tricuspid valve
- 3 cusps with chord tendinae (tether valve to papillary muscle)
- Prevents blood back flow into right atrium (right ventricle contracts –> papillary muscles contract, keep chord tendinae taut)
Bicuspid/mitral valve
- 2 cusps: anterior/posterior leaflet
- Both have chord tendinae tethered to papillary muscles in left ventricle
- Prevents blood back flow back into left atrium
Semilunar valves
- Located where two major arteries leave ventricles
- Pulmonary + aortic valve
Pulmonary valve
- 3 half moon shaped cusps
- prevents blood back flow into right ventricle
Aortic valve
- 3 cusps
- Prevents blood back flow into left ventricle
Blood flow physiology
- Deoxygenated blood enters right side of heart via superior/inferior vena cava (veins)
- Coronary sinus (tiny R atrium opening) collects blood from coronary vessels –> R atrium –> tricuspid valve –> R ventricle –> pulmonary valve –> pulmonary trunk –> pulmonary arteries –> pulmonary capillaries –> alveoli
- Blood connects O2 from alveoli and removes CO2
- Oxygenated blood travels through pulmonary granules –> pulmonary veins –> L atrium –> bicuspid/mitral valve –> L ventricle –> aortic valve –> aorta –> organs, tissues
- Deoxygenated blood returns to heart
Pulmonary and system circulation pump the ___ amount of blood.
Same
Pulmonary circulation
- Low pressure system
- Right side of heart pumps deoxygenated blood through pulmonary circulation to collect oxygen
- Path: R atrium –> R ventricle –> pulmonary arteries –> lungs
Systemic circulation
- High pressure system
- Left side of heart pumps oxygenated blood to systemic circulation
- Path: pulmonary veins –> L atrium –> L ventricle –> aorta –> body
- L ventricle = 3x R ventricle thickness –> inc systemic circulation resistance
Pulmonary vs systemic: pressure
systemic > pulmonary
Pulmonary vs systemic: side of heart
Pulmonary = R Systemic = L
Pulmonary vs systemic: blood oxygenation
Pulmonary: deoxygenation for lungs
Systemic: oxygenated for tissue
Pulmonary vs systemic: ventricle thickness
Pulmonary R ventricle < systemic R ventricle
Ventricular systole
- Ventricular contraction/atrial relaxation
- Occurs during S1 sound
- Aortic valves open –> blood into aorta, pulmonary arteries
- BP: arterial pressure when ventricles squeeze out blood under high pressure
Ventricular diastole
- Ventricular relaxation/atrial contraction
- Occurs during S2 sound
- Tricuspid/mitral valves open –> blood fills ventricles
- BP: ventricles fill with more blood (lower pressure)
Blood distribution
- Average adult: 5L/1.32 gal total blood volume
- oxygenated from lungs –> left heart pump –> distribute to all organs (not equally)
- From organs –> right heart pump –> lungs
Which organs receive blood for metabolic purposes only?
- Heart
- Brain
- Skeletal muscles
- Bone
Which organs receive blood for both metabolic and recondition purposes?
- Lungs
- kidneys
- GI
- intestinal organs
Preload
- Amp of blood in L ventricle before contraction
- Determined by filling pressure (end diastolic pressure)
- “Volume work” of heart
Afterload
- Resistance (load) L ventricle needs to push against to eject blood during contraction
- “Tension work” of heart
Stroke volume (SV)
- Blood volume (L) pumped by heart per contraction
- Determined by amp of blood filling ventricle, compliance of ventricular myocardium
Cardiac output (CO)
- Blood volumed pumped by heart per minute (L/min)
- = Stroke volume * heart rate
Venous return
Blood flow from veins back to atria
Ejection fraction (EF)
- % of blood leaving heart during each contraction
- = (SV end diastolic volume) * 100
Frank-Starling Mechanism
- Ventricular contraction strength related to amp of ventricular myocardial stretch
- Max contract force achieved when myocardial actin, myosin fibers are stretched about 2-2.5 times normal resting length
Blood vessel layers (Tunics)
- Tunica intima (interna): innermost, thin
- Tunica media: middle, smooth muscle
- Tunica externa: outermost, collagen (vaso vasorum: needs own blood supply)
Arteries
- High pressure
- Thicker than veins
- No valves
Types of arteries
- Elastic
- Muscular
- Arterioles
Elastic arteries
Conducting
- Lots of elastic in externa/media
- Stretchy
- Absorbs pressure
- Largest arteries closes to heart
Muscular arteries
Distributing arteries
- Carry blood to organs/tissues
- Thick muscular layer
Arterioles
Smallest
- Branching from artery in organs/tissues
- Resistance regulators
- Tunica media
- Regulate blood flow
- Contract: dec blood flow, inc systemic resistance
- Vasodilate: inc blood flow, dec systemic resistance
- Contraction/dilation = thermoregulation
Veins
- Low pressure
- Can’t tolerate high pressure
- Adaptable to different volumes/pressures
- Valves to resist gravity
Venules
Small veins that connect to capillaries
Capillaries
- One endothelial cell thick
- Exchange nutrients and waste
- Fluid moves out of vessel to interstitial space
- ions: via clefts/pores
- lipid soluble: dissolve and diffuse
Bulk flow - definition
Passive water/nutrient movement across capillary wall down concentration gradient
Bulk flow - features
- Moves large amounts of water, substance in same direction through fenestrated capillaries
- Material movement
- Faster transport method
- Regulates blood, interstitial volume
- Filtration, reabsorption
- Continuous fluid mixing between plasma, interstitial fluid
Bulk flow types
- Filtration
- Reabsorption
Filtration
Bulk flow when moving from blood to interstitium
Reabsorption
Bulk flow when moving from interstitium to blood
Major site of bulk flow
Kidney
