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34 Cards in this Set

  • Front
  • Back
Open Circulatory System
no distinction between blood and extracellular fluid

Molluscs, arthropods
Closed Circulatory System
blood always enclosed in vessels that transport to and from the heart

Annelids; all vertebrates
3 Types of Vessels
Arteries: away from heart
Veins: toward heart
Capillaries: thinnest & most numerous
Functions of the Vertebrate Circulatory System
Respiratory: erythrocytes carry oxygen from lungs to tissues, and CO2 from tissues to lungs

Nutritive: molecules absorbed by the digestive system are transported to the liver then the rest of the body

Excretory: metabolic wastes are filtered in the kidneys and excreted in urine
Hormone transport: from endocrine glands to tissues

Temperature regulation: endotherms maintain constant body temp. using blood vessels just under the epidermis
Blood Clotting: prevent blood loss when vessels are damaged

Immune Defenses: leukocytes provide immunity against many pathogens
O2 and CO2 transport
Immune Defenses
Defence against parasites
Inflammatory response
Immune surveillance
- precursor of tissue macrophage
B lymphocyte
Antibody production
- precursor of plasma cells
T lymphocyte
Cellular immune response
Blood clotting
Blood Cells
include erythrocytes & leukocytes
Plasma is the matrix in which blood cells are suspended

Plasma contains:
Precapillary sphincters
Body can CONTROL the amount of blood in each tissue

Use of precapillary sphincters
Lymphatic System
An open vascular system that reclaims water & solutes that have entered interstitial regions from the bloodstream
Fluid = lymph
Includes lymph nodes, the spleen, & the thymus
Sites of leukocyte production that “filter” the lymph
Fish Heart
modified tube; 4 consecutive chambers
Amphibians and reptiles Heart
both pulmonary & systemic systems

3 chambers: 2 atria & 1 ventricle

Some mixing of oxygenated & deoxygenated blood
Mammals & birds Heart
four-chambered heart
No mixing - very efficient
Involves diffusion of gases across plasma membranes
movement of a substance from an area of high concentration to an area of low conc.

Rate of diffusion depends on: surface area, concentration; & distance
Fish Respiration
Gills: greatly increased surface area for gas exchange
Air contains about 200 mL O2 / L
Water contains about 10 mL O2 / L
Water flows into mouth, then out gills
In bony fishes, blood flows in opposite direction of water to maximize exchange efficiency
Lungs vs. Gills
Gills do not work on land because:
Air is less buoyant than water

Water keeps gills “open”, but gills collapse in air (no structural support)

Water diffuses into air through evaporation

Too much water would be lost through the large surface area of the gills
Amphibians: force air into “lungs” by gulping air, closing mouth, & raising floor of oral cavity
Most gas exchange is actually through skin
Reptiles, birds, mammals: controlled by muscular contraction of thoracic cavity
As cavity volume increases, air pressure decreases, which forces air in
Volume decreases, pressure increases, forcing air out
Protein consisting of 4 polypeptide chains & 4 heme groups

1 Heme group contains one central atom of Iron, which can bind to O2

Found in erythrocytes of vertebrates; plasma & blood cells of invertebrates

Also binds CO2, but not at heme sites

About 20% of blood oxygen is unloaded in tissues

Other 80% is held as a reserve

Affinity for oxygen is lowered in environments with low pH or high temperatures
The maintenance of a relatively stable internal environment in an organism
Usually involves some form of feedback
Negative feedback loops
an activity is negatively influenced by an effect it produces

Ex: Body temperature; blood glucose
Positive feedback loop
an activity is positively influenced by an effect it produces
Ex: Uterine contractions
body fluids have different osmolality than environment
Maintaining homeostasis requires continuous regulation
moles of solute per kg water
osmolality of body fluids is equal to osmolality of environment
Ex: marine invertebrates