Chapter 42 Flashcards
Open System
Open system - organs are soaked in blood
- Body fluid id called hemolymph
- Sinuses interconnecting systems where blood flows - these are the spaces
around the organs.
Closed System
Closed systems - blood confined to vessels
- Blood is separate from interstitial fluid
Cardiovascular system
Human heart - 2 atrium - blood in
- 2 ventricle - blood out
Arteries
the thickest and largest
- Carries oxygenated blood
Veins
large but not as thick
- Carries de-oxygenated blood
Capillaries
smallest and thinnest
- All gas exchange takes place here
- Network of capillaries is called a capillary bed, these spread through tissue
Blood has an up-stream and a downstream, the arterioles are the up stream and blood flows
down stream through the venules. This is relationship to the blood in the capillaries.
Fish
2 chamber heart, 1 atrium and 1 ventricle
- Blood flows from the ventricle to the gills where it becomes oxygenated,
carbon dioxide leaves through the capillary walls.
- Systemic circulation - oxygen rich blood fills the capillary beds, then carbon
dioxide rich blood travels to the atrium
- Gill circulation - blood flows over the gills from the ventricles
Frog
3 chamber heart , 2 atrium and 1 ventricle
- The ventricle pumps the blood into a forked artery then into pulmocutaneous
and systemic circulation.
- Pulmocutaneous circulation - capillaries in gas exchange organs pick up
oxygen then travel to the left atrium. From here it travels to the capillary beds
then to the right atrium
Mammals
4 chamber, 2 atriums and 2 ventricles right ventricle to lungs - blood flows to left
atrium then to left ventricle and into body. Flows through body and deoxygenated blood now
enters the right atrium and back to the right ventricle.
Heart
pumps and relaxes in a rhythmic cycle
- Contracts - pumps blood
- Relaxes - chambers fill with blood
One cycle is called the cardiac cycle
Contraction is systole
Relaxation is diastole
Cardiac output
volume pumped by the left ventricle per minute. To calculate the cardiac output you multiply the stroke volume by the heart rate
Rate of contraction
heart rate ( # of beats per minute )
Stroke volume
amount of blood pumped by the left ventricle each contraction
Atrioventricular valve ( AV )
between atrium and ventricle
- Ventricle contraction closes them. This prevents flow back into atrium
Semilumar valves
this is where the aorta leaves the ventricle
- contraction forces these to open, during relaxation blood starts
to flow back and causes valves to close
Heart murmur
a defect in one or more valves
- You hear a hissing sound, this is the leak
Sinoatrial Node ( SA )
sets the rate for all of the cardiac muscle to contract at the same time
- Also known as the pace maker
- Generates an electrical pulse
- Also controls closing of the AV by impulse
Electrocardiogram ( ECG or EKG )
records impulses
Law of continuity
if the flow is constant, blood will flow faster through capillaries then arteries.
Veins and Arteries - there are 3 layers
- Outer - connective tissue
- Inner - endothelium
- Middle - smooth muscle
Blood pressure
higher in arteries, highest during contraction ( systolic pressure )
- Arteries stretch from pressure of entering blood and retract as blood enters arterioles. This is called peripheral resistance.
Capillaries - 5% to 10% have blood at any time, but there are so many that organs receive enough blood flow or gas exchange.
- Body will divert blood flow to capillaries as needed ( ex. Digestive system )
- About 85% of fluid that leaves the blood at arteriole end of capillaries will re-enter at the venuole end.
Lymphatic system
vessels and lymph nodes, separate from the circulatory system
- Fluids enter the system by diffusion into the lymph capillaries
helps fight infection
Lymph
colorless fluid - formed by interstitial fluids in the lymphatic system
