1. The nervous system has several functions in the body, including:
- Sensory input: It receives information from the external environment and internal body through sensory receptors.
- Integration: It processes and interprets the sensory information, and makes decisions based on that information.
- Motor output: It sends signals to muscles and glands to initiate a response or action.
- Homeostasis: It helps regulate and maintain a stable internal environment by coordinating various body systems.
- Higher mental functions: It is responsible for cognition, memory, emotions, and consciousness.
2. The divisions of the nervous system are:
- Central Nervous System (CNS): It includes the brain and spinal cord, which are the main control centers of the body.
- Peripheral Nervous System (PNS): It includes all the nerves outside of the CNS and is further divided into the somatic nervous system (controls voluntary movements) and the autonomic nervous system (controls involuntary functions).
3. Neurons have three main parts:
- Cell body (soma): It contains the nucleus and other organelles necessary for the neuron's functioning.
- Dendrites: They receive signals from other neurons and transmit them towards the cell body.
- Axon: It transmits signals away from the cell body to other neurons or target cells.
The main functions of each part are:
- Cell body: It integrates incoming signals and generates outgoing signals.
- Dendrites: They receive signals from other neurons and transmit them to the cell body.
- Axon: It conducts electrical impulses (action potentials) away from the cell body to other neurons or target cells.
4. Neuroglia, or glial cells, are supportive cells in the nervous system. The types of neuroglia and their functions include:
- Astrocytes: They provide structural support, regulate ion and nutrient concentrations, and help form the blood-brain barrier.
- Microglia: They act as immune cells, removing damaged cells and debris in the CNS.
- Oligodendrocytes (CNS) and Schwann cells (PNS): They produce myelin, a fatty substance that insulates and speeds up nerve impulses.
- Ependymal cells: They line the cavities of the brain and spinal cord, producing cerebrospinal fluid and helping with its circulation.
5. Neurons can be classified into three types based on their functions:
- Sensory neurons (afferent neurons): They transmit sensory information from sensory receptors to the CNS.
- Motor neurons (efferent neurons): They transmit signals from the CNS to muscles and glands, causing them to contract or secrete.
- Interneurons (association neurons): They reside within the CNS and act as connectors between sensory and motor neurons, facilitating communication between them.
6. A nerve is a bundle of nerve fibers (axons) held together by connective tissue. Nerves transmit electrical signals, called action potentials, between the CNS and other parts of the body. They can carry sensory information from the body to the CNS (afferent nerves) or transmit motor signals from the CNS to muscles and glands (efferent nerves).
7. The spinal cord is a long, cylindrical bundle of nerve fibers that extends from the base of the brain to the lower back. Its main function is to transmit signals between the brain and the rest of the body. It also serves as a reflex center, where involuntary reflex actions can be initiated without involvement from the brain. Additionally, the spinal cord is involved in coordinating certain motor activities and relaying sensory information to the brain.
8. When a reflex is elicited, the essential parts involved are:
- Sensory receptor: It detects the stimulus and generates an electrical signal.
- Sensory neuron: It transmits the sensory signal from the receptor to the spinal cord or brain.
- Integration center: In the case of a spinal reflex, the integration center is located in the spinal cord, where the sensory signal is processed and a response is generated.
- Motor neuron: It carries the motor response generated by the integration center to the effector organ (muscle or gland).
- Effector organ: It carries out the response, such as muscle contraction or glandular secretion.
9. The main parts of the brain and their locations are:
- Cerebrum: It is the largest part of the brain and is divided into two hemispheres. It is responsible for higher mental functions, including cognition, memory, emotions, and voluntary movement.
- Cerebellum: It is located at the back of the brain and is responsible for coordinating movement, balance, and posture.
- Brainstem: It includes the midbrain, pons, and medulla oblongata. It regulates basic functions like breathing, heart rate, blood pressure, and sleep/wake cycles.
- Diencephalon: It includes the thalamus, hypothalamus, and pineal gland. The thalamus relays sensory information to the cerebrum, the hypothalamus regulates homeostasis and controls the endocrine system, and the pineal gland produces the hormone melatonin.
10. The basal ganglia, or basal nuclei, are a group of structures located deep within the cerebral hemispheres of the brain. They are involved in the coordination and control of voluntary movements, as well as the regulation of muscle tone and posture. The basal ganglia also play a role in cognitive functions, such as learning, attention, and emotions. Dysfunction of the basal ganglia can result in movement disorders like Parkinson's disease and Huntington's disease.
