Overview
This lecture covers the structure and function of nervous tissue, focusing on neurons, neuroglial cells, and the direction of electrical signals in motor and sensory pathways.
Nervous Tissue Overview
- Nervous tissue consists of neurons and neuroglial (support) cells.
- Neurons send electrical signals called action potentials.
- Neuroglial cells support and protect neurons.
Motor Neurons
- Motor neurons carry electrical signals from the brain or spinal cord to organs.
- Their main targets are muscles (smooth, cardiac, skeletal) and glands.
- Motor neurons cause movement or glandular secretion by activating these targets.
- The action potential travels one way: from the soma (cell body) in the CNS to the muscle or gland.
Sensory Neurons
- Sensory neurons start in organs and send action potentials to the brain or spinal cord.
- Types of sensory receptors include stretch, pain, touch, and temperature receptors.
- Special senses (vision, hearing, taste, smell) detect external stimuli via unique receptors.
- Proprioception provides feedback about limb position and movement, important for body awareness.
Signal Direction and Function
- Motor pathways: brain/spinal cord → muscle/gland (outgoing signals for movement/secretion).
- Sensory pathways: organ/receptor → brain/spinal cord (incoming signals for sensation/feedback).
- This two-way communication maintains homeostasis by adjusting body responses as needed.
Key Terms & Definitions
- Neuron — a cell that sends and receives electrical signals (action potentials).
- Action Potential — an electrical signal transmitted by neurons.
- Neuroglial Cell — a supportive cell in nervous tissue.
- Motor Neuron — neuron that carries signals from CNS to muscles or glands.
- Sensory Neuron — neuron that carries signals from organs to the CNS.
- Proprioception — sense of body position and movement.
- Central Nervous System (CNS) — consists of the brain and spinal cord.
Action Items / Next Steps
- Review the structure of neurons and the difference between motor and sensory pathways.
- Complete any assigned reading on nervous tissue structure and function.