Tissues (1)

View mindmap
  • Nervous Tissues
    • Three Overlapping Functions
      • Sensory Input: Monitor changes via sensory receptors
      • Integration: Processes and interprets sensory input
      • Motor Output: Initiates a response via effector organs (muscle and glands)
    • Two Parts of Nervous System
      • Central Nervous System (CNS): Brain and Spinal cord.
      • Peripheral Nervous System (PNS): Consists of bundles of nerves that extend from the brain and spinal cord
    • Peripheral Nervous System
      • Consists of Two Main Parts
        • Somatic Nervous System (SNS- Voluntary)- allows conscious control of skeletal muscles.
        • Autonomic Nervous System (ANS- Involuntary)- visceral motor fibres that regulate the activity of smooth and cardiac muscle and glands.
          • Two further subdivisions: Sympathetic, Parasympathetic
            • Typically work in opposition (e.g. if one stimulates, the other inhibits.
      • Two Further Subdivisions
        • Sensory (Afferent) division: conveys impulses to the CNS via somatic or visceral afferent fibres.
        • Motor (Efferent) division: transmits pulse from the CNS to effector organs
    • Neurons
      • Highly specialized cells that conduct messages to and from one part of the body to another
      • Extreme longevity- can last 100+ years
      • Amitotic- lost their ability to divide
      • Exceptionally high metabolic rate
      • Dendrites provide an enormous surface area for receiving signals from other neurons. They convey messages toward the cell body.
      • Signals are not action potential but are short
      • Xons single process that originates from axon hillock and ends at synaptic knob
      • Nerve impulses release neurotransmitters into the extracellular space
    • Myelin Sheath
      • Myelinated fibers conducts nerve impulses rapidly
      • Exceptionally good electrical insulation
      • They are formed by Schwann cells that wrap themselves around nerve fibres, squeezing out their cytoplasm util many concentric layers of plasma membrane enclose the axon
      • Gaps in between adjacent Schwann cells are celled Nodes of Ranvier
      • Important in face impulse transmission
    • Muscle Tissue
      • Skeletal Muscle (Voluntary): Organs that attach and cover the bony skeleton
      • Cardiac Muscle (Involuntary) : Occurs only in the heart, constitutes the bulk of the heart walls
      • Smooth Muscle (Involuntary): Found in the walls of hollow visceral organs where it is used to force liquids and other substances through internal body channels.
    • Skeletal Muscle
      • Discrete organ made up of several kinds of tissues:
        • Muscle Fibers
        • Blood Vessels
        • Connective Tissue
        • Nerve Fibers
      • Components of Skeletal Muscle
        • Each muscle fiber contains myofibrils that run parallel to its length
        • Sarcomeres contain each small structure called myofilaments which are made up of:
          • Myosin (thick filaments)
          • Actin, Tropomyosin, and Troponin (thin filaments)
      • Regulation of Skeletal Muscle Contractions
        • Sarcoplasmic Reticulum: elaborate ER that surrounds each myofibril, running longitudinally and communicating at the H-zone
        • T-tubules: at each A band/ I band junction the sarcolemma of the muscle cell protrudes deep into the cell interior forming elongated T-tubules
        • Electrical impulses from nerves travel along the sarcolemma and into T-tubules whih reach deeply into muscle cell and to every sarcomere.
          • These impulses signal the release of calcium, causing muscle fibre contraction at the same time
      • Sliding Filament Model of Contraction
        • During contraction, the thin filament slide past the thick ones so that the actin and myosin overlap to a greater degree.
        • Myosin heads latch onto myosin-binding on the actin- cross bridge
        • Sliding begins and these heads detach and reattach several times during concentration.
        • The muscle cell shortens: Z-discs are pulled toward the M line and I band shorten.


No comments have yet been made

Similar Human Biology resources:

See all Human Biology resources »See all Tissues resources »