Introduction of nervous system /part-1/

Understanding the Nervous System and Its Functions

Overview of the Nervous and Endocrine Systems

• The nervous system is crucial for controlling behavior, thinking, emotions, motor functions, and decision-making.

• There are two primary systems in the human body: the nervous system and the endocrine system. Their relationship involves communication and interaction.

Structure of the Nervous System

• The human brain contains regions with hormone receptors; for example, neurons in the amygdala have sex hormone receptors (estrogen/progesterone in females; testosterone in males).

• Anatomically, the nervous system consists of two parts:

• Central Nervous System (CNS): Composed of brain and spinal cord.

• Peripheral Nervous System (PNS): Composed of 31 pairs of spinal nerves and 12 pairs of cranial nerves.

Functional Aspects of the Nervous System

• Functionally, there are two parts to the nervous system:

• Somatic part: Involves voluntary actions (e.g., standing up when instructed).

• Autonomic part: Controls involuntary functions (e.g., heart rate changes without conscious control).

Autonomic Nervous System Components

• The autonomic nervous system has two divisions:

• Sympathetic: Prepares body for 'fight or flight' responses.

• Parasympathetic: Promotes 'rest and digest' activities; functionally opposite to sympathetic.

Cellular Composition of Nervous Tissue

• Nervous tissue comprises two main cell types:

• Neurons: Responsible for transmitting signals.

• Glial cells (neuroglia): Supportive cells that outnumber neurons by five to ten times but occupy equal volume within nervous tissue.

• Types of glial cells vary between CNS (astrocytes, oligodendrocytes, microglia, ependymal) and PNS (Schwann cells, satellite cells).

Understanding Neuron Structure and Function

Overview of Soma and Pericardion

• The soma, or cell body, contains a part called the pericardion, which surrounds the nucleus.

• The pericardion is rich in organelles such as mitochondria, ribosomes, rough endoplasmic reticulum (RER), lysosomes, and smooth endoplasmic reticulum.

Cytoskeleton Components

• The cytoskeleton consists of three main components: microfilaments (6 nm), microtubules (24 nm), and intermediate filaments (10-12 nm).

• Microfilaments are also known as actin filaments; microtubules are common across all cells.

• Intermediate filaments vary by cell type: desmin in muscle cells, cytokeratin in epithelial cells, vimentin in fibroblasts, and neurofilament in neurons.

Golgi Complex Functions

• The Golgi complex is well-developed in the pericardion and functions primarily for storage and modification of proteins synthesized in the RER.

• It plays a role in processes like phosphorylation of proteins before they are transported from the soma.

Dendrites and Axon Structure

• Dendrites branch out from the soma; each branch decreases in diameter to increase surface area for synaptic connections.

• An axon maintains a consistent diameter throughout its length; it is insulated by a myelin sheath that enhances signal transmission speed.

Types of Neurons

Multipolar Neurons

• Multipolar neurons are abundant within nervous tissue; they have multiple dendrites extending from one soma.

Bipolar Neurons

• Bipolar neurons feature one axon and one dendrite with an ovoid nucleus; found notably in olfactory mucosa and retina.

Pseudo-Unipolar Neurons

• These neurons possess a round cell body with two branches that function as axons—one receiving impulses while the other sends them. They relate to dorsal root ganglia.

Axonic Neurons

• Axonic neurons lack axons entirely; they consist solely of dendrites. Amacrine cells in the retina exemplify this type.

Functional Classifications of Neurons

• Neurons can be classified into three functional types:

• Motor neurons transmit signals from CNS to effectors (muscles/endocrine organs).

• Sensory neurons receive stimuli from receptors to send signals to CNS.

• Interneurons connect various parts within CNS.

Screenshot Submission Instructions

Overview of Task

• The speaker requests participants to complete a task and submit a screenshot as proof of completion.

• Emphasis is placed on the importance of showing the screenshot to verify that the task has been done correctly.

• The speaker mentions they will compile a list of the first ten individuals who successfully complete the task.

• Only 10% of participants are expected to achieve this, indicating a challenging nature of the task.