Circulatory systems
Biology 2: Form and Function
Circulation
• Transport of
– Nutrients
– Metabolic wastes
– Metabolic gases
– Various elements of immunological system
– Hormonal signals
– Heat energy
The evolution of circulation in animals
• Primitive animals rely upon diffusion as a
mechanism of transport (Porifera, Cnidaria)
• Diffusion becomes inefficient over
distances of 2–3 cells (limits size of
Platyhelminthes)
• Development of a pseudocoelom provided
primitive circulatory sac with fluid
• Eucoelomates (Mollusca onwards)
developed true circulatory systems
Open and Closed Circulation
• Open systems (Mollusca, Arthropoda)
bathe organs in haemolymph. organs
held in secondary spaces (sinuses) that
may join together to form haemocoel
• Closed systems contain circulatory fluid
(blood) in a vascular system that feeds
individual organs
• Both open and closed systems require a
pump (heart)
Hearts
• Hearts have evolved
from two, to three, to
four chambered systems
• Human heart powers
dual circuit (pulmonary
and systemic)
• EKG reflects complex
waveform (systole /
diastole)
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A trip inside the heart...
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The cardiovascular network
Blood contains...
– Plasma (dissolved metabolites, wastes,
hormones, ions, proteins)
– Red blood cells (Erythrocytes = O2/CO2
transport)
– White blood cells:
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Neutrophils (immune defense)
Eosinophils (parasite defense)
Basophils (inflammatory response)
Monocytes (immune surveillance)
B-Lymphocytes (antibody production)
T-Lymphocytes (cellular immune response)
Platelets (blood clotting)
White blood cells have an important
role in our immune system
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The EKG cycle
The PQRST complex
Abnormal EKGs
The Lymphatic system
•Collects fluids and
particles in the interstitial
fluid primarily the result
of capillary leakages
•Filters fluid at Lymph
Nodes, removing foreign
substances
•Foreign substances are
subsequently destroyed
by white blood cell
activity
So what about plants?
• With developmental complexity came a need
for increased circulatory efficiency (cf.
Bryophytes versus gymnoperms)
• Development of vascular tissue in ferns and
upwards
• Presence of vascular tissue, together with
development of stronger fibrous support,
allowed plants to grow taller and compete for
sunlight
Types of transportation
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Diffusion (small scale only)
Root pressure
Transpiration
In vascular plants, use of
– Xylem (water and minerals)
– Phloem (sugars)
Mass
Flow (3)