Chapter 42

No Circulatory System  Exchange across PM directly with environment  Gastrovascular cavity Digestion and distribution

Open Circulatory System  Bathes organs Minimizes diffusion distance  Pumps hemolymph No pigment = move nutrients only  Body movements circulate

Closed Circulatory System  Vessels enter organs Capillaries  Hemoglobin pigments  Allows higher pressure Larger, more complex organisms  Control flow

Cardiovascular System  Heart, vessels, and blood  Direction determines type of vessel  Natural selection modified according to activity levels Number of loops and heart chambers

Cardiovascular System Types Single circulation Double circulation 2 chambers 4 chambers Partial 4 chambers 3 chambers

Heart (tricuspid)(bicuspid) aorticpulmonary

Cardiac Cycle  Systole = contract  Diastole = relax

Beating to its Own Rhythm Bundles of His Electrocardiogram measures activity conducted to skin via body fluids

The Working Heart  Lub-dub, lub-dub, lub-dub AV-semilunar contraction alternates  Cardiac Output is volume of blood/min Heart rate X stroke volume (ventricle contraction)  Heart murmurs Blood moves backward  Myocardial infarction (heart attack) Lack of O 2 kills muscle fibers  Stroke Artery blockage kills nervous tissue

 Endothelium Simple squamous  Middle layer Smooth muscle  Outer layer Connective tissue and Elastin Blood Vessels

Types of blood vessels  Arteries and arterioles Thicker walls, smaller diameter High pressure  Capillaries Lowest velocity Allows diffusion Regulate pressure  Venules and veins Thinner walls, larger diameter Lowest pressure One way valves

The Little Blue Pill  Arterioles Vasoconstriction ○ BP effect? Vasodilation ○ BP effect?  Hormonal and neural control Fight or flight, exercise Nitric oxide

Capillaries  Provide blood to all tissues  Sphincters regulate flow patterns Thoroughfare channel is always open Active or inactive tissues  Arteriole regulation too Digestive Organs While eating While exercising

Human Cardiovascular System Process is continuous Circuits are simultaneous Be able to diagram/explain

Blood Pressure and Flow  Blood flows from high to low pressure  Smaller vessels resistance Velocity slows  in vessel number area Velocity and pressure slow  Allows time for diffusion  in vessel number area Velocity speeds up  Toll booth or accident examples  Pulse and artery stretch

 Blood pressure highest at heart level Fainting Raising wounds  Veins Valves and skeletal muscles ○ Standing on mats ○ Cool downs ‘Cankles’ Circulation and Gravity

Fluid Exchange  B/w capillaries and interstitial fluid  Blood components to large to leave vessel Blood pressure vs. osmotic gradient

Blood  Connective tissue  Plasma is matrix  Cellular Elements Erythrocytes Leukocytes Platelets

Blood Composition (90%) Fragmented cells w/o nuclei infections phagocytes histamine macrophages B- and T-cells With nuclei w/o nuclei

Blood Clotting  Damaged vessel constricts  Platelets form a temporary plug  Fibrin threads trap cells to seal