Bio Notes March 05

# Bio Notes March 05 - Bio Notes Chapter 40 I Physics...

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Bio Notes March 05, 2008 Chapter 40 I. Physics Constrains Biology a. Anatomy vs. Physiology i. Anatomy – Structures (lab) literally the pieces and parts ii. Physiology – Function (lecture) i.e. why do you need this how these parts work iii. Intimately related iv. Video – Friday = Bioenergetics b. Anatomy limited by Physics!! Aero and Hydro – big examples i. Hydrodynamics: water = 1000x more dense than air, so move the water come across resistance 1. Creatures – diverse as Chondrichthyes, Ostrichthyes, Aves, and Mammals come to same boil endpoint in how to deal with water make bodies of similar shape, skinny in front, skinny in back, torpedo-like, can’t have fast-swimming that has flatness to deal with water; Fast swimmers must deal with strengths of water flow on you. ii. Aerodynamics 1. if flier must deal with aerodynamics, need lift, and power to generate forces to provide flight, to get off ground 2. dictate wingshape, slightly different shapes, based on glider, or flapper, fast or slow flier, different variations, but ultimately contrained based on what you do; evolution = limitless, but slightly limited by physical laws (physics) iii. Diffusion limits cell size: 1. Diffusion i.e. oxygen, co2, or nutrients to cells on short scale is incredibly fast, and efficient but once reaches greater range is incredibly slow and inefficient a. Therefore for a cell to be able to survive it has to be in close contact with outside world so it can diffuse oxygen in, co2 out, get nutrients; so individual cell cannot get to big, then center cannot be diffused into efficiently, and cell center would die, therefore whole cell would die. b. So, cell size is limited by diffusion i. Deal by staying small, and single-celled, i.e. amoeba, touch outside, and diffusion can happen rapidly. ii. OR if need to be bigger so don’t get eaten, (evo arms race, Cambrian Explosion) 1. become multi-cellular like cnidarians, tenophorans, and sponges, and just be two cell layers, and still have all cells touching outside environment, either outside outside or gastrovascular cavity, still touching

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outside for diffusion; OR flat, platyhelminthes, parasitic inside body, but flat, so have multi layers, diffuse across
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## This note was uploaded on 04/07/2008 for the course BIOL 1402 taught by Professor Dr.o during the Spring '08 term at SMU.

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Bio Notes March 05 - Bio Notes Chapter 40 I Physics...

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