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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
2 chambers
Single circulation
3 chambers
Partial 4 chambers
Double circulation
4 chambers
Heart
pulmonary
(tricuspid)
aortic
(bicuspid)
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 O2 kills muscle fibers

Stroke
 Artery blockage kills nervous tissue
Blood Vessels

Endothelium
 Simple squamous

Middle layer
 Smooth muscle

Outer layer
 Connective tissue and
Elastin
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

Digestive Organs
While eating
Arteriole regulation too
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
Circulation and Gravity

Blood pressure
highest at heart level
 Fainting
 Raising wounds

Veins
 Valves and skeletal
muscles
○ Standing on mats
○ Cool downs
 ‘Cankles’
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%)
w/o nuclei
With nuclei
infections
B- and T-cells
histamine
macrophages
phagocytes
Fragmented
cells w/o nuclei
Blood Clotting



Damaged vessel constricts
Platelets form a temporary plug
Fibrin threads trap cells to seal