Neural Signalling
A neuron is a specialized nerve cell that is the functional unit of the nervous system. It allows an organism to receive and respond to both internal and external stimuli.
Neural signalling = communication by neurons, it is the process by which an animal responds appropriately to stimuli.
Four components of neural signalling are reception, transmission, integration, and response.
Reception: is the detection of a stimulus. Performed by neurons and by specialized sensory receptors, such as those in the eyes and skin
Transmission: is the movement of a message along a neuron to either another neuron or a muscle or gland.
Integration: is the sorting and interpretation of multiple neural messages and the determination of the appropriate response.
Response: is the output or action resulting from the integration of neural messages.
Classes of Neurons
Afferent neurons: a neuron that carries impulses from sensory receptors to the central nervous system
Inter neurons: a local circuit neuron of central nervous system that relays impulses between afferent and efferent neurons.
Efferent neurons: a neuron that carries impulses from the central nervous system to skeletal muscles. (motor neuron)
Purpose of Central Nervous System
The nervous system is made up of the central nervous system and the peripheral nervous system. The PNS consists of the nerves that connect the brain and spinal cord to the rest of the body. The CNS consists of the brain and spinal cord. The CNS manages body activities by integrating incoming sensory information from the PNS into responses.
Efferent System
It is made up of axons of neurons that carry signals to the muscles and glands, which act as effectors. It is subdivided into the somatic system, which communicates with the skeletal muscles, which communicates with smooth muscles and glands.
Somatic System
Is mainly voluntary, it controls body movements and carries signals from the central nervous system to the skeletal muscles. (it has 31 pairs of spinal nerves)
Spinal Cord
It extends from the base of the brain down through a canal inside the vertebrae of the backbone. It carries impulses between the brain and the PNS and contains the interneuron circuits that control motor reflexes. The interneurons send axons upward through the white matter of the spinal cord to the brain. Efferent nerves in the ventral root carry information from the spinal cord to the muscles and organs.
Brain
It is the major centre that receives, integrates, stores and retrieves information. The interneuron networks generate responses that provie the basis for our voluntary movements, behavior, emotions, learning, reasoning and memory.
There are four lobes of the brain:
- Frontal lobe = located behind the forehead, largest lobe of the brain. They are prone to injury because they sit just inside the front of the skull. This lobe is involved in planning and organizing, problem solving, memory and controlling behavior.
- Parietal lobe = located behind the frontal lobe, holds sensory information. Tells us which way is up, and helps us from not bumping into things. Damage to this lobe can result in inability to locate parts of your body.
- Temporal lobe = located on the sides on the sides of the brain under the parietal lobe. They are responsible for recognizing and processing sound, understanding and producing speech, and some memory. Damage on specific parts of this lobe can result in hearing loss, language problems, and sensory problems, like recognizing people.
- Occipital lobe = located at the lower back of the head. Responsible to receive and process visual information, helps in understanding shapes and colors. Damage to this lobe may result in visual defects, distorted perceptions of size, color and shape.
Cerebellum = Located at the back of our brain, it controls our balance movement and coordination. It allows us to keep our balance and move around. Damage in this part of the brain may result in loss of muscle tone and uncoordinated movement.
Brain stem = Located at the base of the brain, it is composed of the midbrain, the pons, and the medulla. It helps necessary functions like breathing, heart rate, blood pressure, and swallowing. Injury to the brain stem can cause loss of those functions.
Hypothalamus = Located below the thalamus and above the brain stem. It helps us regulate body temperature, hunger/thirst, our mood, it also releases and controls many hormones that we need to function. Injury to the hypothalamus may affect our sex drive, emotions, hunger/thirst, and sleep.
Pituitary Gland = Located at the base of the brain. It helps regulate and release important hormones to our body. It plays an important role for our whole body. Injury to this part of the brain may affect growth in children, depression, sex drive, blood pressure, body temperature and pain.
Amygdala = Located near the hippocampus in the frontal portion of the temporal lobe. Amygdala is involved in the formation and storage of major emotional events in life, long-term memory formation, retain learning, and help us realize danger. Injury may affect memory formation , emotional sensitivity, anxiety and depression.