Animal form and function

Common problems All cells need aqueous environment Gas exchange Nourishment Excrete waste Move

Form and function Anatomy = form Physiology = function Examples: Capillaries and alveoli: 1 cell thick, allow gas ex. Muscle cells: long fibers, allow long lever arm RBC: smooth, round allow flow through vessels Skin: many cells thick, allow for scrapes without lots of blood loss

Body plans Need: exchange with environment Need: aqueous environment for each cell Protist: 1 cell: exchange across cell membrane

Mammals Simple diffusion?

Adaptations Elephant: millions of cells must get glucose and oxygen. Aqueous solution for all cells = interstitial fluid Increase surface area within organ system by: Folds and protrusions

Tissue 4 types of tissue Muscle: contractile Nervous: conduct impulses Epithelial: lines things, secretion Connective: holds things together

Muscle tissue Muscle: Most abundant tissue Smooth, cardiac (desmosomes), skeletal Proteins: actin and myosin Second messenger: Ca++ ATP needed for contraction

Nervous tissue Nervous Excitable, conducts impulses Neuron CNS: brain and spinal cord PNS

Connective tissue Connective tissue: cells in a matrix with proteins Blood to bone Matrix: liquid to solid Fibers: collagen, elastic, reticular

Epithelial tissue Epithelial: linings, secretes Tight junctions: no leaking, small intestine Desmosomes: anchor: skin Simple to stratified

Organs No organs: sponges and cnidarians Have groups of different tissue types together for more complex function.

Bioenergetics Flow of energy through animal Metabolic rate: amount of Energy per unit time Measure by heat lost Or oxygen consumed

Bioenergetic strategies Endothermic: maintain body temperature: Birds Mammals Exothermic: warmed by external source Some very stable If in a stable environment Invertebrates, fish Differ in source of warmth

Metabolic rate Amount Energy needed per gram of body weight inversely related to body size Mouse has high metabolic rate Elephant has low metabolic rate. BUT, requires more energy overall

Metabolic rate Smaller animals have higher metabolism: greater surface to volume ratio: harder to maintain body temperature.

BMR Basal metabolic rate: at rest Endotherm: 1,600 – 2,000Kcal/day Maximum rate: can not sustain for long Use: ATP that’s already present Then make some anaerobically by glycolysis Start to break down glycogen in liver and muscle cells

Homeostasis Maintain stable internal environment Receptor – control center- effector Conformers: may let one variable change with environment.

Feedback loops Positive feedback: childbirth Negative feedback: 1 product of reaction goes back and shuts down earlier step in reaction

Homeostasis: thermoregulation Body temperature monitored in hypothalamus receptor Information integrated in CNS Integration center Effector organs: If cold: skeletal muscle: shiver Erector pili: hair stands up Smooth muscle: close capillary beds in periphery If hot: sweat gland

Adaptations for thermoregulation 1. insulation: feathers, hair, fat 2. circulatory: vasodilate, vasoconstrict, concurrent heat exchange (birds, marine mammals) 3. cooling by evaporation 4. behavior 5. hormones

acclimatization Adjust to new environment over a few days Grow thicker fur Change metabolic rate Ectotherms: change at cellular level: make different enzymes Change proportions of sat/unsat fats Heat-shock proteins: protect other proteins from denature

Torpor Adaptation: decreased activity & metabolism Hibernation Estivation: summer torpor