Chapter 40: Basic Principles of Animal Form and Function

1. Chapter 40:Basic Principles of Animal Form and Function Periods 3-4

2. Animal Form and Function are Correlated at all Levels of Organization • Anatomy: the structure of an organism and its study • Physiology: the processes and functions of an organism and their study • Physical constraints on animal size and shape • Physics laws govern strength, diffusion, movement, and heat exchange • Natural selection often shapes similar adaptations when diverse organisms face similar environmental challenges (convergent evolution) • Ex: body shape of fast swimmers • Physics influences the maximum size of animals • As body dimensions increase, thicker skeletons are required to maintain strength • As body size increases, more muscle is required for locomotion • Exchange with the Environment • Each cell of an animal must have access to an aqueous environment • Two layered sacs and flat shapes maximize exposure to the surrounding environment • Interstitial fluid: fluid filling the spaces between animal cells • Complex body plans also have a circulatory fluid (blood) • Exchange between interstitial fluid and circulatory fluid enables cells to obtain nutrients and get rid of wastes

3. Hierarchical Organization of Body Plans • Organ System: a group of organs that work together to perform vital body functions • Organ: a specialized center of body function composed of several different types of tissues • Tissue: an integrated group of cells with a common function, structure, or both • 1. Epithelial Tissue: sheets of tightly packed cells that line organs and body cavities as well as external surfaces • 2. Connective Tissue: tissue that functions mainly to bind and support other tissues, having a sparse population of cells scattered through an extracellular matrix • Collagenous Fibers: made of collagen (protein); provide strength combined with flexibility; nonelastic and do not tear easily when pulled lengthwise • Elastic Fibers: long threads made of elastin (protein); easily stretched but are also resilient, snapping back to original length when tension is released • Reticular Fibers: made of collagen and continuous with collgenous fibers; form a tightly woven fabric that joins connective tissue to adjacent tissues • 3. Muscle Tissue: long muscle cells that can contract on its own or when stimulated by nerve impulses • 4. Nervous Tissue: tissues made up of neurons and supportive cells

4. Animal Tissues 1. Epithelial Tissue • The close packing (tight junctions) enables the tissue to function as a barrier • Epithelium: the cells of epithelial tissue, which form active interfaces with the environment • Cubodial: dice • Columnar: bricks standing on end • Squamous: like floor tiles • Simple Epithelium: single cell layer • Stratified Epithelium: multiple tiers of cells • Pseudostratified Epithelium: a single layer of cells varying in height 2. Connective Tissue • Consists of a sparse population of cells scattered though an extracellular matrix • Major Types of Connective Tissue in Vertebrae… • Loose Connective Tissue: collagenous, elastic, and reticular fibers bind to underlying tissues and hold organs in place • Cartilage: abundance of collagenous fibers embedded in a rubbery matrix made of a protein-carb complex called chondroitin sulfate • Fibrous Connective Tissue: dense with collagenous fibers; form parallel bundles to maximize nonelastic strength; tendons (attach muscle to bone) and ligaments (connect bones at joints) • Adipose Tissue: loose connective tissue that stores fat in adipose cells distributed throughout the matrix; insulates the body and stores fuel as fat molecules

5. Animal Tissues Continued Connective Tissue (Cont.) • Blood: liquid ECM (plasma); consists of water, salts, and dissolved proteins; erythrocytes (red blood cells), leukocytes (white blood cells), and cell fragments (platelets) • Bone: mineralized connective tissue; bone-forming cells are called osteoblasts • The connective tissue that holds many tissues/organs together and in place contains scattered cells of varying function… • Fibroblasts: cells that secrete the protein ingredients of the extracellular fibers • Macrophages: cells that engulf foreign particles and debris of dead cells by phagocytosis COMPREHENSION CHECK: Connective Tissue Review 3. Muscle Tissue • Filaments containing the proteins actin and myosin, which enable muscles to contract • Skeletal Muscle: known as striated muscle due to a striped (striated) appearance; responsible for voluntary movement; consists of long cells called muscle cells • Cardiac Muscle: forms the contractile wall of the heart; striated and has contractile properties similar to skeletal muscle; unconscious task=contraction of the heart • Smooth Muscle: responsible for involuntary body activities; lacks striations; found in the walls of the digestive tract, urinary bladder, arteries, and other internal organs • Muscle Tissue Video 4. Nervous Tissue • Neurons (nerve cells) have extensions (axons) that are specialized to transmit nerve impulses • Glial cells (glia) help nourish, insulate, and replenish neurons

6. Communication: Nervous System vs. Endocrine System • Nervous System • Neurons transmit electric/chemical signals to specific target cells • Nerve impulsestravel along the neuron extensions (axons) • Info conveyed by the specific pathways that the signal takes • Transmission is very fast, each impulse takes fraction of a second to reach target cell • Well suited for rapid responses to environment and controlling fast locomotion and behavior. • Ex: Impulses cause your hand to pull away quickly from a hot surface. • Endocrine System • Hormones are signaling molecules that are released into the bloodstream to reach all locations in the body. • Different hormones cause specific effects and only cells with the specific receptors for the particular hormone responds. • Depending on which cells have the specific receptor for the hormone, the hormone may have only one effect in one location or in many sites throughout the body. • It is slow acting, but long term. This is because the hormone remains in the bloodstream and target tissue for a longer time period. • Ex: Insulin controls levels of glucose in the blood by binding to and regulating virtually every cell outside the brain

7. Regulators and Conformers • A regulatorfor an environmental variable uses internal control mechanisms to regulate homeostasis when faced with an external change. • A river otter keeps its body at a constant temperature regardless of the temperature of the water which it swims in. • A conformer for an environmental variable conforms its internal conditions to conform to the extern changes in the environment. • A largemouth bass conforms its internal temperature to the lake it lives in. • An organism can be a conformer and a regulator to different environmental variables. • The bass is a conformer for temperature, but is a regulator for solute concentration. The concentration in its blood and fluid differs from the concentration of the water it lives in.

8. Homeostasis: Positive and Negative Feedback • Homeostasis is state in when the organism maintains a constant internal environment despite external environmental changes. • The organism maintains a specific variable at or near a set point. • A stimulus fluctuates the variable from the set point, and the sensor detects the stimulus to trigger a physiological response that helps return the variable to the set point. • Negative feedback reduces the stimulus to prevent the reaction from continuing. • Exercise increases body temperature. The nervous system detects this increase and triggers sweating. The evaporation of moisture cools body to return temperature to the set point. • The presence of a product of the system results in a decrease in the production of that product. • Ex: trpoperon. • Positive feedback amplifies the stimulus where the product of a reaction influences or increases the forward direction of the system. • In child birth, the pressure of the baby’s head stimulates the uterus to contract, which results in greater pressure and heightening the contractions.

9. -Thermoregulation is the process by which animals maintain their internal temperature within a tolerable range. Thermoregulation -Ectothermsand endotherms manage their heat budgets very differently 1. Endothermic animals, such as birds and mammals, use metabolic heat to regulate their body temperature. 2. Ectothermic animals, such as snakes and most fishes, gain most of their heat from the external environment. Ectotherm Endotherm

10. -Many endotherms and ectotherms can alter the amount of blood flow between the body core and the skin. Vasodilation vs. Vasoconstriction • Vasodilation is an increase in the diameter of surface blood vessels near the body surface. • Triggered by nerve signals that relax the muscles • In endotherms, vasodilation usually warms the skin, increasing the transfer of body heat. - Lizard • The reverse process, vasoconstriction, reduces blood flow and heat transfer by decreasing the diameter of surface vessels. -Jack Rabbit, blood vessels in the ears keeps it from overheating

11. Countercurrent Exchange • Another circulatory adaptation is countercurrent exchange, the transfer of heat or solutes in adjacent fluids that flow in opposite directions. • Countercurrent heat exchanger- an antiparallel arrangement of blood vessels that involves heat transfer • Arteries and veins are near one another. As warm blood passes through the arteries, heat transfers to the colder venous blood returning from the extremities.

12. Ectotherms and Endotherms • Many animals can adjust to a new range of environmental temperatures by a physiological response called acclimatization. • Ectotherms and endotherms acclimatize differently. • In endotherms, acclimatization often includes adjusting the amount of insulation-growing fur and shedding • In ectotherms, there are adjustments at the cellular level • Cells may increase the production of certain enzymes • Membranes change the proportions of saturated and unsaturated lipids to remain fluid at different temperatures. • Some ectotherms produce “antifreeze” compounds, or cryoprotectants, to prevent ice formation in body cells. Bear is an example of an endotherm acclimation. Bear has a thicker coat in winter and sheds it in the summer.

13. Bioenergetics and Metabolic Rates • Bioenergetics: the overall flow and transformation of energy in an organism • A Metabolic Rate is the sum of all the biochemical reactions that use energy over a given period of time. • Energy is measured in Joules or Calories • Energy can be measured by Rates of Oxygen inhaled and CO2 produced.

14. BMR vs. SMR • Basal Metabolic Rate (BMR) is the minimum metabolic rate of an animal at rest and not experiencing stress. BMR is measured at a “comfortable” temperature. Standard Metabolic Rate (SMR) is the metabolic rate of an unstressed animal at rest at a particular temperature.

15. Energy Budgets and Size The relationship between metabolic rate and size are directly related.

16. Energy Conservation • Torpor is a physiological state in which activity is low and metabolism decreases. • Hibernation is a long-term torpor is reaction to winter coldness and food scarcity. Estivation is a summer torpor in response to high temperatures and food scarcity. Some animals exhibit a daily torpor usually as an adaptation to feeding patterns. Ex: Bats

17. COMPREHENSION CHECK __ Long-term period of sleep during summer months __ General term for a change in activity and metabolism __ Metabolic rate at a particular temperature __ Metabolic rate at a comfortable temperature __ Bats feeding in the night and go dormant during the day __ A grizzly bear in the winter months • Torpor • Estivation • Hibernation • Daily Torpor • BMR • SMR B A F E D C

18. Review Video