Chapters 19 & 20- Heart and Circulation

Epicardium

Outermost heart wall with coronary bvs through this layer

Myocardium

Thick muscular middle layer of heart

Endocardium

Smooth inner layer of heart and BVs

Artery

high pressure. thick middle layer, no valves

Veins

low pressure, thick outer layer, and valves

Tunica Intima

Simple squamous and basement membrane

Tunica Media

Smooth muscle and elastic fibers

Tunica Externa

Collagen and elastic fibers

Circulatory Function

Transport oxygen, nutrients, hormones, and waste throughout body to ensure homeostasis

Coronary Vessels

Supply heart with oxygenated blood and remove waste

Pulmonary Vessels

Transport deoxygenated blood from the heart to the lungs and return oxygenated blood back to the heart

Atrial Contraction

Atrial pressure rises and blood pushed into the ventricles (AV valves open and semilunar valves closed)

Ventricular Contraction

Ventricular pressure rises and AV valves closes (LUB) and semilunar valves open

Ventricular Relaxation

Pressure drops semilunar closes (DUB) and AV valves open

AV node

Slowest conduction as it allows time for ventricles to fill

Blood reservoirs

Veins and venules

Greatest BP

When the heart beats/contracts (systole)

Lowest BP

When the heart rests between beats (diastole)

P Wave

Atrial Depolarization (contract)

QRS Complex

Ventricular Depolarization (contract)

T Wave

Ventricular Repolarization (relax)

Lub

AV valve closes

Dub

Semilunar valve closing

Factors Affecting BP

Contraction of heart, Blood volume, BV number/length/diameter/stretching, viscosity, diet, H2O level

Peripheral Resistance

Vessel Diameter, blood viscosity, and vessel length

Respiratory (thoracic) Pump

During inhalation thoracic cavity pressure decreases, abdominal pressure increases which pulls blood towards heart

Cardiac Suction

Heart relaxes creating a slight vacuum, drawing blood into the atria

Skeletal Muscle Pump

Muscle contracts and squeezes veins so blood is pushed toward heart

Gravity

Helps blood flow downward towards heart and is why valves are crucial in legs so blood doesn’t pool in feet

Anastomosis

Alternative blood vessel connections

Capillary Exchange

Diffusion, filtration, and reabsorption

Proprioreceptors

Detect movement location in muscles/joints

Chemoreceptors

detect O2, CO2, and pH

Baroreceptors

Detect Pressure found in carotid sinus and aortic arch

Hydrostatic Pressure

Pressure exerted by a fluid enclosed in a space, forces fluid OUT of capillaries

Osmotic Pressure

Pressure exerted to move fluid from tissues back to capillaries, forces fluids back INTO capillaries

Hydrostatic > Osmotic

Fluid leave= Filtration

Osmotic > Hydrostatic

Fluid enters=Reabsorption

Causes of Edema

Low venous return, low blood albumin, and lymphatic blockage