neurology and the central nervous system nervous system 

Spring Break Announcement

  • You do not have to attend class on Tuesday or Thursday of this week because of spring break.

Upcoming Topics and Assignments

  • After spring break, the course will resume with discussions about the neurological system.

  • Assignment due on central nervous system focusing on a lab.

    • Due Date: The following Tuesday after break.

  • Hands-on dissection of a sheep's brain will be conducted on the following Thursday.

    • Scalpels and other cutting tools will be used for the dissection.

    • Students required to identify various brain parts during dissection and take pictures for labeling purposes.

Lab Details

  • Lab 6: CNS Brain Dissection Recording.

    • Recording will provide instructions for the dissection and areas to identify on the brain.

    • Students are encouraged to watch this recording before the dissection day, preferably by the 26th.

Lab Exam Information

  • A lab exam will occur the following Thursday night after the dissection.

    • Study Guide Provided: Includes items to recognize and their locations on the brain.

    • The exam's format includes multiple-choice and true/false questions concerning all covered material like the integumentary system and tissues.

    • Emphasis on studying thoroughly is advised to avoid guessing during the exam, as it may lead to uncertain outcomes.

Nervous System Overview

  • The nervous system governs all body functions, with nerve innervation present throughout.

  • Various neurological conditions were mentioned:

    • Meningitis: Inflammation of the meninges (protective membranes covering the brain and spinal cord).

    • Alzheimer's Disease: Named after Alois Alzheimer; associated with dementia and cognitive decline.

    • Lou Gehrig's Disease (ALS): Named after the baseball player; affects motor neurons.

    • Encephalitis: Inflammation of the brain (encephalon).

    • Multiple Sclerosis: A chronic disease affecting the myelin sheath of neurons in the CNS.

Homeostasis and Temperature Regulation

  • Homeostasis is a body's balance maintenance.

    • Body's responses include shivering when cold and sweating when hot.

    • Terms:

    • Hyperthermia: Elevated core body temperature.

    • Hypothermia: Decreased core body temperature due to exposure to cold (e.g., swimming in cold lakes).

Nervous System Functions

  • The nervous system operates in two main components:

    • Afferent Pathway (Sensory Input): Carries impulses from receptors to the CNS.

    • Efferent Pathway (Motor Output): Carries impulses from the CNS to effectors (muscles/glands).

Structure of Neurons

  • Neurons consist of:

    • Cell Body: Contains the nucleus and organelles.

    • Dendrites: Network of branches receiving signals from other neurons.

    • Axon: Long projection transmitting impulses away from the cell body, terminating at the axon terminal.

    • Axon Hillock: Region where the axon and cell body meet and impulses are propagated.

Types of Neurons

  • Multipolar Neurons: Common in the brain and spinal cord.

  • Bipolar Neurons: Present in the retina and olfactory regions.

  • Unipolar Neurons: Mainly sensory neurons, found in the ganglia of spinal and cranial nerves.

Component Physiology

  • The neuron's primary function is to convert stimuli to action potentials (nerve impulses).

    • At resting state, neurons maintain a membrane potential.

    • Action Potentials: Triggered when a threshold voltage is reached, traveling along axons in one direction.

Myelination

  • Myelinated axons transmit action potentials faster than unmyelinated axons due to the presence of myelin sheath, formed by:

    • Schwann Cells: In peripheral nervous system (PNS).

    • Oligodendrocytes: In central nervous system (CNS).

  • Node of Ranvier: Gaps in myelination, facilitating rapid signal transmission.

Excitatory vs Inhibitory Neurons

  • Excitatory Neurons: Promote action potentials (e.g., depolarization).

  • Inhibitory Neurons: Prevent action potentials (e.g., hyperpolarization).

Neuroglial Cells

  • Support neuronal function:

    • Astrocytes: Nutrient supply to neurons, maintain chemical environment.

    • Oligodendrocytes: Myelination of CNS axons.

    • Microglial Cells: Immune function and debris cleanup.

    • Ependymal Cells: Produce cerebrospinal fluid (CSF).

Blood-Brain Barrier

  • Protects the CNS from toxins, only allowing certain substances to cross (e.g., glucose, oxygen).

  • Challenging for performing chemotherapy related to brain tumors due to difficulty crossing the barrier.

Cerebrospinal Fluid (CSF)

  • Produced in the lateral ventricles; circulate through the brain's ventricular system to the subarachnoid space.

  • Functions include:

    • Mechanical protection (buoyancy and shock absorption).

    • Circulation of nutrients.

Brain Regions

  • Cerebral Hemispheres: Left and right; involved in thought processes, memories.

  • Diencephalon: Thalamus (sensory relay) and hypothalamus (homeostasis).

  • Brainstem: Consists of midbrain, pons, medulla oblongata (controls basic survival functions).

  • Cerebellum: Coordinates movement and balance.

Spinal Cord Anatomy

  • Extends from the medulla; has cervical, thoracic, and lumbar regions.

  • Conus Medullaris: The end of solid spinal cord; beyond which is the cauda equina (nerve roots).

  • Meninges: Protective layers covering the CNS:

    • Dura Mater: Tough outer layer.

    • Arachnoid Mater: Middle layer.

    • Pia Mater: Directly on the surface of the CNS.

Exam Preparation

  • Focus on understanding the structure and function of the nervous system, neuron types, neuroglial cells, and CSF circulation.

  • Review the study guide and practice identifying brain regions during dissection on sheep brain.