3. Flashcards
3 Main Components of the Cardiovascular System
Heart (pump) - muscular pump that directs the flow of blood through the blood vessels
Blood Vessels - conduits through which the blood flows
Blood - fluid that circulates around the body carrying materials to and from cells
How can an organism not have a circulatory system?
Unicellular can diffuse
Some organisms have characteristics which allow them to move fluid to cells (move through body cavity)
- flagella - porifera
- cilia - platyhelminthes (interstitial fluid by bulk flow)
- muscle contractions - cnideria
Types of Fluid in the Body
Interstitial Fluid - extracellular fluid that directly bathes the tissues (ensures tissues are hydrated)
Blood - fluid that circulates within the vessels of a CLOSED circulatory system (e.g. vertebrate)
Lymph - fluid that circulates the secondary circulatory system (Lymphatic System)
- similar to blood, without the large molecules
- elevates fluid build up in the interstitial space and return to blood vessels
- various infections and diseases result in the lymphatic system stop working, build up of fluid
Hemolymph - fluid that circulates (through vessels and tissues) of an OPEN circulatory system
- fluid similar to blood with a few different factors
What is a hemocyte?
A blood cell
Composition of Blood/Hemolymph
- water
- dissolved ions
- dissolved proteins
- organic solutes
- hemocytes
Function of Blood
- oxygen transport and storage
- nutrient transport and storage
- phagocytosis
- immune defense
- blood clotting
Components of Vertebrate Blood
- Plasma - fluid, acellular, many proteins involved in health
- Erythrocytes - carry oxygen, hematocrit
- Leukocytes - immune, other cells, clotting
Centrifugation of vertebrate blood
- Seperated by density
Bottom: RBC, medium component (45%)
Middle: WBC, smallest component (<1%)
Top: plasma, largest component (55%)
Erythrocytes & Viscosity
- erythrocytes increase viscosity
- blood fluid `with less cells is less disturbed
- animals with weak hearts cannot pump blood rich with erythrocytes
Blood viscosity increases with age
- factor in fetus to maintain viscous blood even with increase of erythrocytes due to weak heart, in comparison to adults
Erythrocytes & Size
- size of RBCs varies among vertebrates
- mammal < birds and amphibians
- some contain DNA (nucleus) and some do not
–> bird, amphibian, reptile have nucleus - differing sizes was mapped out in 1875 by George Gulliver (drew over 80 vertebrate species rbc to scale)
Erythrocytes & Evolution
- RBCs have evolved independently many times
- in invertebrates found in interstitial fluid, not hemolymph
- system must be very important to survival if it developed in different lineages
Blood Vessels
Conduit for movement of fluid
- vertebrate circulatory plan is uni-directional
- capillaries is site of diffusion
- birds and mammals have two circuits: pulmonary and systemic
heart - lungs - heart
heart- body - heart
Blood Vessels Regulating Temperature
- peripheral vessels (veins) vasodilator or vasoconstrictor to maintain temperature homeostasis
- to reduce heat, dilate vessels nearer to external
- reserve heat, constrict vessels into body
- diameter change is completed by smooth muscle
- nerve system can influence a change in diameter
Varicose veins (blood pooling in legs) can be removed without affecting the function of an organism – why? What would happen if you did the same to arteries?
Varicose veins is related to blood pooling in the veins. Removal of these veins allows rerouting of the blood into other veins to prevent pooling. Veins can be removed because they carry deoxygenated blood, thus is not vital to be near all tissues, and does not impact blood pressure. If an artery were to be removed the other arteries that the blood must be rerouted to would be unable to handle the added pressure and blood flow
