Metabolism
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4 major types of tissue
epithelial muscle connective nervous
epithelial tissue
lines surface of body (skin) or inner surface of organ (digestive tract, blood vessels) specialized for secretion and absorption lines blood vessles and acts as a barrier to outside world
muscular tissue
skeletal muscle, cardiac muscle, smooth muscle
nervous tissue
neurons and glial cells
connective tissue
bone, cartilage, tendons, blood, fat, adipose tissue (fat), loose connective tissue (collagen and elastin) connect different parts of body by binding and supporting tissues. secrete matrix Consist of cells and the extracellular matrix
groups of tissues–>
organs–> organ systems
cellular respiration equation
food+O2–> water + CO2 + energy (heat+ATP)
metabolic rate
rate of energy consumption
how do we measure metabolic rate?
oxygen consumption- proxy for how much energy we are consuming
Factors that increase with metabolic rate
increase exercise, smaller body size, increased consumption, temperature of environment, more waste
Basal Metabolic Rate (BMR)
how much energy is needed to support basic physiological processes metabolic rate of resting animal
when do we measure BMR?
when animal is resting in a comfortable thermal environment and has not eaten recently
total energy expenditure
basal metabolism+energy used in physical activity+ energy in digesting food
Body size and energy needs
elephant takes more energy, but smaller animals need more energy per gram of body than bigger animals
why do smaller animals have greater energy needs per unit of body weight?
high surface area to volume ratio. Lose heat to the environment easily
mass specific metabolic rate
gets lower as an animal is larger, even though the animal has a larger total metabolic rate
metabolic rate scales
linearly with body mass, but not with body mass and metabolic rate/g
what conform to the laws of physics?
body plans, adaptations, body shape etc.
Small animals exchange
can exchange with environment directly through teh surface of bodies with passive diffusion larger animals can’t contact external environment- require transport
Surface area
amount of materials that can cross the cell membrane/exchange with environment r^2
Volume
amount of chemical activity in cell. r^3 increases more rapidly
SA to V challenge: needs and heat
challenge to satisfy metabolic needs with amount of material Want a large SA to Volume ratio so materials can easily travel through the small volume and large surface area lose heat due to surface area large animals have a smaller surface area to volume ratio, retain more metabolic heat. less surface area to lose heat. Lower metabolic rate. small animals have high metabolism, lose heat to enviornment
Sa to V limited by
rate of diffusion (sa r^2)
intracellular fluid
60% of total body water. fluid inside cells