Animal Coordination: Nervous & Endocrine Systems

Chapter 35: Animal Nervous Systems

  • Function and Evolution

    • Multicellular organisms (except sponges) possess a nervous system.

  • Phylogeny of Nervous Systems

    • Sponges: No nervous system.
    • Cnidarians: Simple nervous systems in jellyfish and corals.
    • Bilaterians: More complex systems in flatworms, insects, and vertebrates.

  • Types of Neurons

    • Sensory neurons: Detect stimuli.
    • Interneurons: Process information within the CNS.
    • Motor neurons: Transmit impulses to effectors (muscles and glands).

  • Human Brain Neurons: Approximately 100 billion nerve cells.

  • Nervous System Complexity

    • Neurons interconnect to create structures: nerve nets, nerves, ganglia, brains.
    • Complexity is reflective of an organism's lifestyle.

Chapter 37: Animal Endocrine Systems

  • Endocrine Function

    • The endocrine system is made up of glands and secretory cells, communicating through hormones.
    • Responds to various environmental changes (day length, temperature, predators, mates).

  • Collaborative Roles of Endocrine and Nervous Systems

    • Nervous system: Quick responses, short duration.
    • Endocrine system: Slower responses, longer duration.

  • Endocrine Control in Growth

    • Example: Metamorphosis in insects involving molting through instars (developmental stages).

  • Hormonal Control and Amplification

    • Hormones can lead to significant physiological changes across multiple organ systems.
    • Hierarchical signaling:
    • Hypothalamus: Releases corticotropin-releasing hormone.
    • Pituitary Gland: Releases ACTH.
    • Adrenal Cortex: Releases cortisol and regulates glucose production in the liver.

  • Epinephrine in Stress Response

    • Increases heart rate, alters blood flow, and promotes energy release.

  • Homeostasis and Negative Feedback

    • The body maintains equilibrium through feedback loops involving the pancreas and hormonal modulation (insulin and glucagon manage glucose levels).

Chapter 41: Animal Reproduction and Development

  • Types of Reproduction

    • Asexual:
    • Binary Fission: Cell divides, producing clones (e.g., bacteria).
    • Budding: New organism develops from the parent (e.g., Hydra).
    • Fragmentation: A part of the organism regenerates into a new individual.
    • Parthenogenesis: Females produce eggs that develop without fertilization.

  • Sexual Reproduction

    • Involves meiosis and fertilization, leading to genetic diversity.
    • Benefits:
    • Faster adaptation due to mutation.
    • Purging harmful mutations.
    • Defense against parasites.

  • Fertilization Types

    • External Fertilization: Gametes released into environment; common in aquatic species.
    • Internal Fertilization: Occurs within the female’s body; a common adaptation among land-dwelling species (e.g., mammals, reptiles).

  • Reproductive Strategies

    • r-strategists: Produce many offspring with minimal parental care (e.g., many fish).
    • K-strategists: Fewer offspring with greater parental investment (e.g., elephants, mammals).

  • Amniotes and the Amniotic Egg

    • Adaptation for terrestrial life involving structures (amnion, yolk sac) to protect developing embryos.
    • Types of reproductive strategies include oviparity, ovoviviparity, and viviparity (live birth) common in various animal taxa.