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:• 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

• Diffusion (small scale only)

• Root pressure

• Transpiration

• In vascular plants, use of– Xylem (water and minerals)– Phloem (sugars)

Mass Flow (3)