Endocrine Regulation and Nervous System Fundamentals

Endocrine System Regulation

How is the endocrine system regulated? Endocrine gland activity is regulated by the brain. The brain manages the endocrine system through two glands: the hypothalamus and the pituitary glands. The hypothalamus directs, and the pituitary glands produce and secrete.

Neuron Structure and Classification

Neurons: These transmit messages (nerve impulses) and have a unique appearance.

• Cell body: This is where the nucleus is located; it contains most of the cytoplasm and organelles. It forms part of the grey matter.
• Dendrites: These are branched projections connected to other neurons that receive information from them.
• Axon: A long tail structure where information passes from here to the next neuron or cell. A group of axons is called a nerve. In the brain and spinal cord, axons form the white matter.

Three Types of Neurons

• Sensory neurons: These carry information from the receptors to the central nervous system.
• Interneurons: These make up the central nervous system and connect sensory and motor neurons.
• Motor neurons: These carry messages from the central nervous system to the effectors.

The Mechanism of Synaptic Transmission

1. The nerve impulse travels from the dendrite to the end of the axon.
2. At the end of the axon, there is a pre-synaptic neuron containing vesicles with neurotransmitters.
3. Synapse: The impulse releases the neurotransmitters into the space between the two cells.
4. The neurotransmitters interact with the receptors on the other side of the synapse, which is the post-synaptic neuron or cell.
5. The receptors in the post-synaptic cell react; this is a dendrite of the next neuron or a cell.

Anatomic and Functional Divisions

Anatomic division:

• Central Nervous System (CNS): Neurons that are in the brain and spinal cord.
• Peripheral Nervous System (PNS): Neurons that are outside of the organs of the CNS.

Functional divisions: These are categorized by the source of sensory information and the type of response that is triggered.

• Autonomic nervous system: Nerve pathways are responsible for involuntary regulation. There are two types of pathways: parasympathetic and sympathetic.
• Somatic nervous system: Pathways responsible for sensory and motor functions under conscious control. These might be voluntary or involuntary.

Central Nervous System Protection and Grey Matter

Central nervous system: It is comprised of the brain and the spinal cord. It has two protective layers:

• The soft: Meninges, which consist of three distinct membranes: dura mater, arachnoid mater, and pia mater.
• The hard: Made of bone; the cranium encases the brain and the vertebral column encases the spinal cord.
• Cerebrospinal fluid.

Grey matter: Formed by cell bodies and the dendrites of neurons, these are the control centers where neurological messages are processed.