CH 40 Basic Principles of Animal Form and Function 40.1 Animal form and function are correlated at all levels of organization

CH 40 Basic Principles of Animal Form and Function

40.1 Animal form and function are correlated at all levels of organization

 The organization of an animal’s body emerges from the grouping of specialized cells into tissues, tissues into functional units called organs, and organs into organ systems.

 Because form and function are correlated, examining anatomy often provides clues to physiology, a biological function.

 An animal’s size and shape are fundamental aspects of form that significantly affect the way the animal interacts with its environment.

 Epithelial tissue : covers the outside of the body and lines internal organs and cavities.

 Consistent with their barrier function, epithelial cells are tightly packed. They rest on a dense mat of extracellular matrix, the basement membrane, which may function in metabolism, development, and excretion.

 Epithelia are described according to the number of cell layers (simple or stratified) and the shape of the surface cells (cuboidal, columnar, or squamous).

 Some epithelia are specialized for absorption and secretion. The mucus secreted by the mucous membranes lining the digestive and respiratory tracts lubricates and moistens these surfaces.

 Connective tissue : bind and support other tissues. Loose connective tissue, the body’s binding and packing material, consists of fibroblasts and macrophages interspersed among collagenous, elastic, and reticular fibers.

 Adipose (fat) tissue is a specialized type of loose connective tissue.

 Fibrous connective tissue, found in tendons and ligaments, is made of dense, parallel bundles of collagenous fibers.

 Cartilage, bone, and blood are also connective tissue. Cartilage is a strong yet flexible support material consisting of collagenous fibers in a rubbery foundation secreted by chondrocytes.

 The hard substance of bone is secreted by cells called osteoblasts.

 The muscle tissue of vertebrates consists of skeletal, cardiac, and smooth, which differ in shape, striation, and nervous control.

 The endocrine system broadcasts signaling molecules called hormones everywhere via the bloodstream, but only certain cells are responsive to each hormone.

40.2 Feedback control maintains the internal environment in many animals

 Animals regulate (control) certain internal variables while allowing other internal variables to

conform to external changes.

 Homeostasis is the maintenance of a steady state despite internal and external changes.

 These mechanisms are usually based on negative feedback, in which the response reduces the stimulus. In contrast to this, positive feedback involves amplification of a stimulus by the response and often brings about change in state.

 Regulated change in the internal environment is essential to normal function.

 Circadian rhythms are the daily fluctuations in metabolism and behavior tuned to the cycles of light and dark in the environment.

 Other environmental changes may trigger acclimatization, a temporary shift in the steady state.

40.3 Homeostatic processes for thermoregulation involve form, function, and behavior

 The internal environment surrounding the cells is usually very different from the external environment.

 The internal environment is carefully controlled and regulated by the process of homeostasis.

 An animal maintains its internal temperature within a tolerable range by thermoregulation.

 Endotherms- warmed mostly by heat generated by metabolism.

 Ectotherms- get most of their heat from external sources.

 In thermoregulation, physiological and behavioral adjustments balance heat gain and loss, which occur through radiation, evaporation, convection, and conduction.

 Insulation and countercurrent exchange reduce heat loss, whereas panting, sweating, and bathing increase evaporation, cooling the body.

 The hypothalamus acts as the thermostat in the mammalian regulation of body temperature.

 In animals, size and shape are fundamental aspects of form and function, that significantly affects the way an animal interacts with its environment.

Physical support on land depends on adaptations of proportions and posture.

 Natural laws govern the relationship between an animal’s body weight and strength of its support structures.

 Posture often reduces the strain on support structures produced by a larger, heavier body.

 Body size and shape affect interactions with the environment. Each cell of a multicellular animal must have access to an aqueous environment.

 Simple 2 layered sacs and flat shapes maximize exposure to the surrounding medium.

 More complex body plans have highly folded internal surfaces specialized for exchanging materials with the environment.

40.4 Energy requirements are related to animal size, activity, and environment

 Animals are heterotrophs that harvest chemical energy from the food they ingest, and store it for short-term use in ATP.

 Since we cannot make our own food, the functions of an animal’s cells, tissue, organs, and systems depend on cellular work powered by chemical energy in ATP.

 An animal’s metabolic rate is the total amount of energy used in a unit of time. Measured by the amount of heat an animal gives off or by how much O

it consumes.

 Metabolic rate provides clues to an animal’s bioenergetic “strategy.”

 Torpor is a state of decreased activity and metabolism, conserving energy during environmental extremes (hibernation).

 An animal’s metabolic rate is the total amount of energy used in a unit of time. Measured by the amount of heat an animal gives off or by how much O

it consumes.

 Metabolic rates range from minimum levels for supporting life, to maximum levels for performing peak activities. Mammals: High metabolism. Reptiles: Low metabolism.

 Metabolic rate per gram is inversely related to body size among similar animals. Mice have a higher metabolism than elephants. Probably due to heat loss and surface area to volume ratio.

Vocabulary:

1. Anatomy: The structure of an organism.

2. Physiology: The processes and functions of an organism.

3. Interstitial Fluid: The fluid filling the spaces between cells of most animals.

4. Tissues: Groups of cells with a similar appearance and a common function.

5. Organs: Tissues organized into functional units.

6. Organ System: Groups of organs that work together, providing an additional level of organization and coordination.

7. Epithelial Tissues: Sheets of tightly packed cells that line organs and body cavities as well as external surfaces.

8. Connective tissue: Animal tissue that functions mainly to bind and support other tissues, having a sparse population of cells scattered through an extracellular matrix.

9. Fibroblasts: A type of cell in loose connective tissue that secretes the protein ingredients of the extracellular fibers.

10. Macrophages: A phagocytic cell present in many tissues that functions in innate immunity by destroying microbes and in acquired immunity as an antigen- presenting cell.

11. Tendons: A fibrous connective tissue that attaches muscle to bone.

12. Ligaments: A fibrous connective tissue that joins bones together at joints.

13. Adipose Tissue: A connective tissue that insulates the body and serves as a fuel

reserve; contains fat-storing cells called adipose cells.

14. Bone: A connective tissues consisting of living cells held in a rigid matrix of collagen fibers embedded in calcium salts.

15. Cartilage: A flexible connective tissue with an abundance of collagenous fibers embedded in chondroitin sulfate.

16. Skeletal Muscle: A type of straited muscle that is generally responsible for the voluntary movements of the body.

17. Smooth Muscle: A type of muscle lacking the striations of skeletal and cardiac muscle because of the uniform distribution of myosin filaments in the cells; responsible for involuntary body activities.

18. Cardiac Muscle: A type of striated muscle that forms the contractile wall of the heart.

Its cells are joined by intercalated disks that relay the electrical signals underlying each heartbeat.

19. Nervous Tissue: Tissue made up of neurons and supportive cells.

20. Neurons: A nerve cell; the fundamental unit of the nervous system, having structure and properties that allow it to conduct signals by taking advantage of the electrical charge across its plasma membrane.

21. Glial Cells: Cells of the nervous system that support, regulate, and augment the function of neurons.

22. Endocrine System: In animals, the internal system of communication involving hormones, and ductless glands that secrete hormones, and the molecular receptors on or in target cells that respond to hormones; functions in concert with the nervous system to effect internal regulation and maintain homeostasis.

23. Nervous System: In animals, the fast-acting internal system of communication involving sensory receptors, networks, networks of nerve cells, and connections to muscles and glands that respond to nerve signals; functions in concert with the endocrine system to effect internal regulation and maintain homeostasis.

24. Hormones: In multicellular organisms, one of many types of secreted chemicals that care formed in specialized cells, travel in body fluids, and act on specific target cells in other parts of the organism, changing the target cells’ functioning.

25. Regulator: An animal for which mechanisms of homeostasis moderate internal changes in a particular variable in the face of external fluctuation of that variable.

26. Conformer: An animal for which a internal conditions conforms to (changes in accordance with) changes in an environmental variable.

27. Homeostasis: The steady-state physiological condition of the body.

28. Set Point: In homeostasis in animals, a value maintained for a particular variable, such as body temperature or solute concentration.

29. Stimulus: In feedback regulation, a fluctuation in a variable that triggers a response.

30. Sensor: In homeostasis, a receptor that detects a stimulus.

31. Response: In feedback regulation, a physiological activity triggered by a change in a variable.

32. Negative Feedback: A form of regulation in which accumulation of an end product of a process slows a process; in physiology, a primary mechanism if homeostasis, whereby pa change in a variable triggers a response that counteracts the initial change.

33. Positive Feedback: A form of regulation in which an end product of a process speeds up that process; in physiology, a control mechanism in which a change in a variable triggers a response that reinforces or amplifies the change.

34. Circadian Rhythm: A physiological cycle of about 24 hours that persists even in the absence of external cues.

35. Acclimatization: Physiological adjustment to change in a n environmental factor.

36. Thermoregulation: The maintenance of internal body temperature within a tolerable

range.

37. Endothermic: Referring to organisms that are warmed by heat generated by their own metabolism. This heat generally maintains relatively stable body temperature higher than that of the external environment.

38. Ectothermic: Referring to organisms for which external sources provide most of the heat for temperature regulation.

39. Integumentary System: The outer covering of a mammal’s body, including skin, hair, and nails, claws or hooves.

40. Countercurrent Exchange: The exchange of a substance or heat between two fluids flowing in opposite directions.

41. Hypothalamus: The ventral part of the vertebrate forebrain; functions in maintain homeostasis, especially on coordinating the endocrine and nervous systems; secretes hormones of the posterior pituitary and releasing factors that regulate the anterior pituitary.

42. Bioenergetics: The overall flow and transformation of energy in an organism.

43. Metabolic Rate: The total amount of energy used in a unit of time.

44. Basal Metabolic Rate: The metabolic rate of a resting, fasting, and nonstressed endotherm at a comfortable temperature.

45. Standard Metabolic Rate: The metabolic rate of a resting, fasting, and nonstressed ectotherm at a particular temperature.

46. Torpor: A physiological state in which activity is low and metabolism decreases.

47. Hibernation: A long-term physiological state in which metabolism decreases, the

heart and respiratory system slow down, and the body temperature is maintained at a

lower level than normal.