Lab 1: Nervous System Overview

Lab 1 Nervous System

• Overview of the skull, meninges, and ventricles
• The nervous system lab covers the anatomy of the brain, spinal cord, and associated structures.

Ventricles

• The ventricles are fluid-filled spaces within the brain.
• There are four ventricles: the lateral ventricles, third ventricle, cerebral aqueduct, and fourth ventricle.
• The ventricles produce and circulate cerebrospinal fluid (CSF).
• The ventricles are a series of connected cavities within the brain.

Meninges

• The meninges are protective membranes surrounding the brain and spinal cord.
• The three layers are dura mater, arachnoid mater, and pia mater.
• The dura mater is the tough, outermost layer.
• The arachnoid mater is the middle layer.
• The pia mater is the delicate, innermost layer.
• These connective tissues provide a cushion for the brain.

CSF

• Cerebrospinal fluid (CSF) is a clear, colorless fluid that circulates within the brain and spinal cord.
• CSF cushions and protects the central nervous system.
• CSF is produced by the choroid plexus in the ventricles.
• Arachnoid granulations are responsible for reabsorbing CSF back into the blood.
• The CSF protects against trauma and injuries to sensitive tissues.

Overview of the Brain

• The brain has three primary regions: the cerebrum, cerebellum, and brain stem.
• The cerebrum is associated with higher-level functions like thinking, memory, and language.
• The cerebellum controls motor coordination and balance.
• The brain stem regulates essential functions like breathing and heart rate.

Cerebral Cortex

• The cerebral cortex is the outermost layer of the cerebrum.
• It consists of gray matter (nerve cell bodies) and white matter (myelinated axons).
• Different areas of the cortex are responsible for different functions.

Basal Nuclei (Basal Ganglia)

• The basal nuclei (basal ganglia) are groups of nerve cells deep within the cerebrum.
• They play a crucial role in coordinating movement.

Diencephalon

• The diencephalon is the region between the cerebrum and the brainstem, containing the thalamus, hypothalamus, epithalamus.
• The thalamus relays sensory information.
• The hypothalamus controls vital functions like hormone release and temperature regulation.
• The epithalamus includes the pineal gland, which is involved in circadian rhythms.

Pituitary

• The pituitary gland is a small endocrine gland located at the base of the hypothalamus.
• It releases hormones that regulate various bodily functions.

Vertebral Column

• The vertebral column is formed by a series of vertebrae.
• These vertebrae enclose and protect the spinal cord in the spinal canal.
• The structural features vary among the spinal levels: cervical, thoracic, lumbar, sacral, and coccygeal.

Vertebrae

• The vertebrae are the fundamental building blocks of the spine.
• Key features of a single vertebra include the vertebral body, spinous process, vertebral canal, and transverse processes.
• These various regions support diverse functions of the vertebral column's overall architecture.

Spinal Cord

• The spinal cord is a long, slender bundle of nerve tissue that extends from the brain stem.
• The spinal cord relays messages between the brain and the rest of the body.
• The spinal cord comprises gray matter (nerve cell bodies) and white matter (myelinated axons).
• The central canal contains cerebrospinal fluid.

Spinal Cord - Flow of Information

• Afferent pathways relay information to the central nervous system (brain).
• Efferent pathways carry information from the central nervous system to the muscles.
• The spinal cord acts as a critical relay station for sensory input and motor output.

Spinal Cord- Medical Applications

• Epidural injections involve administering drugs into the epidural space outside the dura mater; it is used for pain relief.
• Spinal taps/lumbar punctures are procedures that collect CSF for diagnostic purposes.

Resting Membrane Potential (RMP)

• RMP is the electrical potential difference across the cell membrane of an inactive neuron.
• It is the result of ion gradients, selective permeability, and ion pumps.
• Ion pumps (e.g., Na+/K+ pump) maintain ionic gradients.

Action Potentials (APs)

• APs are rapid changes in the electrical potential across a neuron's membrane.
• They are triggered when the membrane potential reaches a threshold value.
• Depolarization (Na+ influx), repolarization (K+ outflow), and hyperpolarization are consecutive stages of AP propagation.
• The refractory period follows each action potential, during which new action potentials cannot be generated.

Synaptic Transmission

• Synaptic transmission is the process where signals are relayed across a synapse between two neurons or a neuron and a muscle cell.
• Neurotransmitters like acetylcholine (ACh) convert electrical signals into chemical signals.
• Neurotransmitter binding to receptors triggers a response in the postsynaptic cell.

General Mechanism of Action (Neuromuscular Synapse)

• Action potentials in the presynaptic neuron trigger the release of neurotransmitters (ACh).
• These neurotransmitters diffuse across the synaptic cleft.
• Neurotransmitter binding to receptors initiates a response in the postsynaptic cell (a muscle).