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Chapter 39: Animal Form and Function

39.1 Form, Function, and Adaption

  • Biologists who study animal anatomy and physiology are studying adaptations-heritable traits that make individuals more likely to survive and reproduce in a certain environment than individuals that lack those traits.

  • The most important constraint on adaptation, though, maybe trade-offs-inescapable compromises between traits.

  • During mating, a male cricket produces a spermatophore, a packet of sperm surrounded by a large, gelatinous mass.

    • The male deposits the spermatophore on the female’s genital opening.

    • After mating, the female begins to eat the gelatinous mass.

  • Phenotypic change in an individual in response to environmental fluctuations is referred to as acclimatization.

39.2 Tissues, Organs, and Organ System: How Does Structure Correlate with Function?

  • A tissue is a group of cells that function as a unit.

  • Nervous tissue consists of nerve cells, which are also called neurons, and several types of supporting cells.

    • Neurons transmit electrical signals, which are produced by changes in the permeability of the cell’ s plasma membrane to ions.

  • Muscle tissue was a key innovation in the evolution of animals-like nervous tissue, it appears in no other lineage on the tree of life.

  • The skeletal muscle attaches to bones and exerts a force on them when it contracts.

    • Skeletal muscle is responsible for most body movements.

    • It has long cells with a striated, or striped, appearance produced by an overlapping arrangement of proteins.

  • Cardiac muscle makes up the walls of the heart and is responsible for pumping blood throughout the body.

    • The branching pa ern of cardiac muscle allows electrical signals to spread throughout all cells of the heart, resulting in their coordinated contraction and relaxation.

  • Smooth muscle cells, which are tapered at each end, form muscle tissue that line the walls of the digestive tract and the blood vessels.

    • Contraction and relaxation of smooth muscle help move food through the digestive tract and regulate blood pressure.

  • An organ is a structure that serves a specialized function and consists of two or more tissues; a gland is an organ at secretes specific molecules or solutions such as hormones or digestive enzymes.

  • Connective tissues consist of cells that are loosely arranged in a liquid, jellylike, or solid matrix.

  • An organ system consists of groups of tissues and organs that work toge er to perform one or more functions.

39.3 How Does Body Size Affect Animal Physiology?

  • Metabolism is 1e sum of all chemical reactions that occur within an organism.

    • Given that metabolism requires energy, the metabolic rate is the overall rate of energy consumption by an individual.

  • Because an individual’ s metabolic rate varies dramatically with its activity, the accepted convention is to report the **basal metabolic rate (BMR)**一the rate at which an animal consumes oxygen while at rest, with an empty stomach, under normal temperature and moisture conditions.

39.4 Homeostasis

  • Homeostasis (literally, “ alike-standing”) is defined as stability in the chemical and physical conditions within an organism’s cells, tissues, and organs.

  • Many organisms are able to regulate their internal conditions to actively maintain relatively constant internal conditions even when the environment fluctuates.

  • For example, many aquatic animals do not maintain their body temperature above the ambient temperature because they would lose heat quickly to the surrounding water.

    • Instead, these animals conform to environmental conditions.

  • Like the thermostat in a home heating system, each of these systems has a set point-a target range of values for the controlled variable.

  • Homeostatic systems are based on negative feedback.

    • When negative feedback occurs, effectors return internal conditions to set-point values.

39.5 Thermoregulation: A Closer Look

  • An animal that is an endotherm (“inner-heat”) produces adequate heat to warm its own tissues, while ectotherm (“outer-heat”) relies principally on heat gained from the environment.

  • Homeotherms (“alike-heat”) keep their body temperature constant, while in poikilotherms (“varied-heat”), body temperatures rise or fall depending on environmental conditions.

Chapter 39: Animal Form and Function

39.1 Form, Function, and Adaption

  • Biologists who study animal anatomy and physiology are studying adaptations-heritable traits that make individuals more likely to survive and reproduce in a certain environment than individuals that lack those traits.

  • The most important constraint on adaptation, though, maybe trade-offs-inescapable compromises between traits.

  • During mating, a male cricket produces a spermatophore, a packet of sperm surrounded by a large, gelatinous mass.

    • The male deposits the spermatophore on the female’s genital opening.

    • After mating, the female begins to eat the gelatinous mass.

  • Phenotypic change in an individual in response to environmental fluctuations is referred to as acclimatization.

39.2 Tissues, Organs, and Organ System: How Does Structure Correlate with Function?

  • A tissue is a group of cells that function as a unit.

  • Nervous tissue consists of nerve cells, which are also called neurons, and several types of supporting cells.

    • Neurons transmit electrical signals, which are produced by changes in the permeability of the cell’ s plasma membrane to ions.

  • Muscle tissue was a key innovation in the evolution of animals-like nervous tissue, it appears in no other lineage on the tree of life.

  • The skeletal muscle attaches to bones and exerts a force on them when it contracts.

    • Skeletal muscle is responsible for most body movements.

    • It has long cells with a striated, or striped, appearance produced by an overlapping arrangement of proteins.

  • Cardiac muscle makes up the walls of the heart and is responsible for pumping blood throughout the body.

    • The branching pa ern of cardiac muscle allows electrical signals to spread throughout all cells of the heart, resulting in their coordinated contraction and relaxation.

  • Smooth muscle cells, which are tapered at each end, form muscle tissue that line the walls of the digestive tract and the blood vessels.

    • Contraction and relaxation of smooth muscle help move food through the digestive tract and regulate blood pressure.

  • An organ is a structure that serves a specialized function and consists of two or more tissues; a gland is an organ at secretes specific molecules or solutions such as hormones or digestive enzymes.

  • Connective tissues consist of cells that are loosely arranged in a liquid, jellylike, or solid matrix.

  • An organ system consists of groups of tissues and organs that work toge er to perform one or more functions.

39.3 How Does Body Size Affect Animal Physiology?

  • Metabolism is 1e sum of all chemical reactions that occur within an organism.

    • Given that metabolism requires energy, the metabolic rate is the overall rate of energy consumption by an individual.

  • Because an individual’ s metabolic rate varies dramatically with its activity, the accepted convention is to report the **basal metabolic rate (BMR)**一the rate at which an animal consumes oxygen while at rest, with an empty stomach, under normal temperature and moisture conditions.

39.4 Homeostasis

  • Homeostasis (literally, “ alike-standing”) is defined as stability in the chemical and physical conditions within an organism’s cells, tissues, and organs.

  • Many organisms are able to regulate their internal conditions to actively maintain relatively constant internal conditions even when the environment fluctuates.

  • For example, many aquatic animals do not maintain their body temperature above the ambient temperature because they would lose heat quickly to the surrounding water.

    • Instead, these animals conform to environmental conditions.

  • Like the thermostat in a home heating system, each of these systems has a set point-a target range of values for the controlled variable.

  • Homeostatic systems are based on negative feedback.

    • When negative feedback occurs, effectors return internal conditions to set-point values.

39.5 Thermoregulation: A Closer Look

  • An animal that is an endotherm (“inner-heat”) produces adequate heat to warm its own tissues, while ectotherm (“outer-heat”) relies principally on heat gained from the environment.

  • Homeotherms (“alike-heat”) keep their body temperature constant, while in poikilotherms (“varied-heat”), body temperatures rise or fall depending on environmental conditions.