Human Anatomy and Physiology: Skeletal Cartilage and Nervous System

Posted on Jan 30, 2025 in Biomedical Sciences

Skeletal Cartilage

Skeletal Cartilage:

  • Hyaline: Provides support, flexibility, and resilience (e.g., ribs, elbow, shoulder).
  • Elastic: Contains more elastic fibers (e.g., external ear, epiglottis).
  • Fibrocartilage: Rich in collagen, provides tensile strength (e.g., intervertebral discs).

Nervous System

  • Central Nervous System (CNS): The command center, consisting of the brain and spinal cord.
  • Peripheral Nervous System (PNS): Carries messages to and from the CNS, including cranial and spinal nerves.

Sensory (Afferent) Division – Input

  • Somatic: Consciously perceived sensations (e.g., the five senses).
  • Visceral: Unconscious sensations (e.g., blood chemistry, organ walls).

Motor (Efferent) Division – Output

  • Somatic: Controls skeletal muscles and movement.
  • Autonomic: Regulates cardiac muscles, glands, and smooth muscles.

Cells in Nervous Tissue

  • Neurons: Excitable cells that transmit electrical signals.
  • Neuroglia (Glial Cells): Supporting cells.

CNS Cells

Astrocytes, microglia, ependymal cells, and oligodendrocytes.

PNS Cells

Satellite cells and Schwann cells.

Neuron Structure

Dendrites (receive information) -> Axon (initiates action potential) -> Synaptic bulb (releases neurotransmitters).

Segments

Receptive -> Initial -> Conductive -> Transmissive.

Glial Cells (Support Tissue)

CNS Functions

  • Astrocyte: Forms the blood-brain barrier, regulates interstitial fluids, and provides support.
  • Ependymal Cell: Lines ventricles and assists in the production and circulation of cerebrospinal fluid (CSF).

PNS Functions

  • Satellite Cell: Regulates waste exchange.
  • Neurolemmocyte (Schwann Cell): Insulates axons and allows for faster action potential propagation.

How Neurons Work: They carry electrical messages, which flow via positive and negative ions (K+, Na+, Ca2+, Cl-).

CNS: Brain Lobes

  • Frontal: Involved in motor control, motivation, planning, and memory.
  • Parietal (Middle): Processes sensory information (e.g., taste, some visual input).
  • Occipital (Rear): The visual center.
  • Temporal (Center): Involved in hearing, smell, learning, memory, and emotional responses.
  • Insula: Processes language and taste.

Brain Areas

Diencephalon

Thalamus (sensory relay, emotion, movement) + Hypothalamus (homeostasis, physical response to emotion, pain, pleasure, body temperature, hormone release) + Epithalamus (Pineal gland -> melatonin).

Brain Stem

  • Midbrain: Controls subconscious muscle activity, eye movements, and coordinates automatic eye and head movements with stimuli.
  • Pons: Links the cerebrum and cerebellum.
  • Medulla: Contains cardiovascular and respiratory centers, as well as reflex centers for sneezing and coughing.

Cerebellum

Consists of two hemispheres and three lobes; located behind the spinal cord. It is involved in unconscious proprioception.

PNS: Sensation

Sensation: The registration of stimuli, generation of sensory information, and transmission to the CNS.

Stimulus: A detectable change in the environment that acts on a receptor.

Somatosensation: Sensory information from the skin to the musculoskeletal system.

Spinal Nerves

8 pairs of cervical nerves > 12 thoracic > 5 lumbar > 5 sacral > 1 coccygeal.

12 Cranial Nerves

  1. Olfactory: Smell.
  2. Optic: Vision.
  3. Oculomotor: Eye muscles, pupil changes.
  4. Trochlear: Superior oblique eye muscle.
  5. Trigeminal: Sensory from scalp, nasal cavity, face, oral cavity, and teeth.
  6. Abducens: Lateral rectus eye muscle.
  7. Facial: Taste from anterior 2/3 of the tongue, facial expression, saliva production.
  8. Vestibulocochlear: Hearing and balance.
  9. Glossopharyngeal: Sensory and taste from posterior 1/3 of the tongue, sensory from the pharynx.
  10. Vagus: Innervates the heart, lungs, and abdominal organs.
  11. Accessory: Innervates the trapezius muscle.
  12. Hypoglossal: Tongue movement.