blood in animals Flashcards
Single circulatory system
- blood flows through the heart once for each circuit of the body
- low pressure
Double circulatory system
- blood flows through the heart twice for each circuit of the body
- high pressure
Open circulatory system
- blood is NOT enclosed in vessels
- blood comes directly into contact and bathes tissues and cells
- blood pours out of directly from the heart into the body cavity
Closed circulatory system
- blood is closed within vessels
- cells are bathed in tissue fluid NOT blood
- blood pumped at high pressures
Types of blood vessels
- arteries
- capillaries
- veins
Arteries
carry oxygenated blood away from the heart at high pressure (except pulmonary artery)
- thick walls = withstand pressure
- narrow lumen = maintains high pressure
- outer collagen layer = withstand pressure
- elastic tissue layer = stretching
- smooth muscle layer
Arterioles
- small vessels which distribute blood from arteries to capillaries
Capillaries
- thin walls = short diffusion distance
- SITE of gas exchange between tissue fluid and blood
- narrow lumen = erythrocytes close to walls
- leaky walls = allow substances to leave
Veins
carry deoxygenated blood into the heart at low pressure
- thin walls = low pressure
- wide lumen = low pressure
- lots of collagen, little elastic in walls
contain VALVES
Venules
- collect blood from capillaries and lead to veins
Tissue fluid
formed by plasma leaking from capillaries (leaky walls)
the fluid surrounds cells and supplies oxygen and nutrients to them
all dissolved substances in the blood plasma go into the tissue fluid EXCEPT proteins and waste
blood plasma - oxygen, carbon dioxide, proteins, glucose, amino acids
Movement of fluid
arteriole end = high hydrostatic pressure, low oncotic pressure, fluid exits capillary - NET OUTFLOW
venule end = low hydrostatic pressure, high oncotic pressure, fluid enters capillary - NET INFLOW
