3/3 a+p

Nodes of Ranvier

• Definition: Nodes of Ranvier are small gaps found along the axon of a neuron.

• Discovery: Named after Doctor Ranvier, who discovered these nodes.

Axonal Terminals

• Axonal Terminal: The endpoint of the axon where signals are transmitted.

• Signal Transmission: Signals travel along the neuron through a process called action potential.

Synapse and Synaptic Cleft

• Synapse: The junction where the axonal terminal of one neuron (neuron A) communicates with the dendrite of another neuron (neuron B).

• Synaptic Cleft: The small gap between neuron A's axonal terminal and neuron B's dendrite where neurotransmitters operate.

• Function: Signal from neuron A is transmitted to neuron B across this cleft.

Neurotransmitters

• Definition: Chemicals that transmit signals across the synapse.

• Function: Released into the synaptic cleft by neuron A, they bind to specific receptors on neuron B's dendrite, facilitating signal transmission.

• Importance in Sensation: Enables sensation, e.g., feeling pressure from touching an object.

Impact of Nerve Damage

• Transmission of Impulse: Damage to nerves can decrease impulse transmission.

• Associated Diseases: Examples include diabetes, where nerve transmission is affected.

Blood Cells and Leukocytosis

• Red Blood Cell Production: Occurs in the bone marrow, essential for oxygen transport.

• Leukocytosis: Refers to the increased white blood cell (WBC) count, typically due to infection.

  • Function of White Blood Cells: Protects the body against infections; involved in immune responses.

Glycogen and Glucose

• Glycogen: Stored form of glucose found primarily in the liver.

• Insulin Action: When blood glucose levels rise, insulin is released from the pancreas to convert excess glucose into glycogen.

Cell Membrane Structure & Function

• Cell Membrane: Acts as a boundary for the cell, maintains integrity and regulates entry/exit of substances.

• Composition: Comprised of a phospholipid bilayer, which is selective in allowing materials to pass.

  • Functionality: Selectively allows certain molecules to enter and exit the cell to maintain cellular homeostasis.