Central Nervous System Essay

The nervous system is made up of basic units called neurons. The main role of the neurons is to receive, integrate and transmit information throughout the body. There are some neuroglial cells found in nervous system aswell which provide support to the neurons by giving protection and nourishment Neurons have nerve processes that looks like finger like projections extended from the nerve cell body. They also contain axons and dendrites which enable them to transmit signals throughout the body. Normally, axon carry signals away from the cell body and dendrites carry signals toward the cell body according to Regina Bailey (2013). Neurons have three different shapes: bipolar, unipolar and multipolar where bipolar has two neuronal processes coming out of the cell body, unipolar has only one neuronal process coming out of the cell body and multipolar has many neuronal processes coming out of the cell body.

This stage is called repolarisation. The K+ channels then close, the sodium-potassium pump restarts, restoring the normal distribution of ions either side of the cell surface membrane and thus restoring the resting potential. In response to this the Na+ channels in that area would open up, allowing Na+ ions to flood into the cell and thus reducing the resting potential of the cells. If the resting potential of the cell drops to the threshold level, then an action potential has been generated and an impulse will be fired.

The frontal lobe is located at the front of the brain and is associated with reasoning, motor skills, higher level cognition, and expressive language.

B ) (1) neurotransmitter released (2) diffused across the synaptic cleft to a receptor protein (3) binding of the transmitter opens pores in the ion channels and negative ions move in.

As an action potential travels down the axon of the presynaptic neuron, the action potential reaches the axon terminal synaptic vesicles which migrate toward the synapse. They then release neurotransmitters into the synaptic cleft. The neurotransmitters travel through the synaptic cleft and bind to ligand-gated ion channels on the postsynaptic neuron membrane. The channels open and allow chemicals to enter the cell (i.e. sodium). Then positively charged sodium enters the cell and causes the cell to depolarize. The depolarization spreads down the axon and an action potential is generated. The process then starts over at the axon terminals.

The midbrain is located above the pons. The midbrain has an area called the substantia nigra which holds different nuclei. The midbrain is responsible for the body 's movement that is not covered by the cerebellum. The neurotransmitter dopamine, that produced by

The cerebral cortex is the largest outer most part of the brain. It consist of tissue known as gray matter which is made of neuronal bodies. The optimal function of the cerebral cortex is vitally important. All information necessary to sustain life is stored and processed in the cerebral cortex. The tissue are divided into the left and right sides which are joined together by the corpus callosum. The cerebral cortex is divided into four lobes, the frontal, parietal, occipital, and temporal lobe. Each area carrying its own set of functions and responsibilities. These four lobes together make up the primary somatosensory area of the brain which controls the five sensory systems in the brain taste, olfaction, touch, hearing and vision. These systems receive sensory information from the thalamic nerve projections. The primary motor area of the brain consist of a much smaller area located within

1. Describe the structure of a neuron and explain the function of each of its major parts.

When a membrane is excited depolarization begins. When the membrane depolarizes the resting membrane potential of -70 mV becomes less negative. When the membrane potential reaches 0 mV, indicating there is no charge difference across the membrane. the sodium ion channels start to close and potassium ion channels open. By the time the sodium ion channels finally close. The membrane potential has reached +35 mV. The opening of the potassium channels allows K+ to flow out of the cell down its electrochemical gradient ( ion of like charge are repelled from each other). The flow of K+ out of the cell causes the membrane potential to move in a negative direction. This is referred to as repolarization. ( Marieb & Mitchell, 2009). As the transmembrane potential comes back down towards its resting potential level and the potassium channels begins to close, the trasmembrane potential level goes just below -90mV, causing a brief period of hyperpolarization (Martini, Nath & Bartholomew, 2012). Finally, as the potassium channels close, the membrane turns back to its resting potential until it is excited or inhibited again.

The CNS contains the brain and spinal cord. Its main functions include: processing, integrating, and coordinating sensory information and motor instructions. The sensory data conducts information that is being processed from internal and external conditions the body is experiencing. Motor commands regulate and control peripheral organs (skeletal muscles). The brain functions under memory, emotions, learning, and intelligence. The PNS consist of the neural tissue found outside of the CNS. It functions in sending data to the CNS which motor commands are than carried out to the peripheral tissues/systems. Multiple nerve fibers send sensory data and motor commands in the PNS. The nerves that assist with transmitting data include the cranial nerves and spinal nerve. However, the PNS can be divided into afferent (to bring in) and efferent (to bring out) divisions of transferring data. The afferent division functions in bringing in sensory data to the CNS. Sensory structures are receptors that detect internal/external environmental change and adjusting accordingly. The efferent division functions in carrying out motor commands from the CNS to glands, muscles, and adipose tissue. The efferent division contains somatic

Depolarization in membrane potential triggers an action potential because nearby axonal membranes will be depolarized to values near or above threshold voltage.

The parietal lobe is responsible for our motor co-ordination; motor impulses to the muscles are

The cranial nerves, spinal nerves and ganglia make up the PNS. The cranial nerves connect to the brain. The cranial and spinal nerves contain the axons (fibres) of sensory and motor nerve

Whenever the balance is altered, the process of transmitting electrical signals, which is called action potential initiates by carrying information across a neuron’s axon; which is called resting membrane potential. This process occurs as uneven ions distribution flow across cell membrane, creating electrical potential. As a result, the duration of active potential can be as fast as 1 ms. Similarly, the average resting membrane is between -40 mV and -80 mV. Since the membrane from inside is more negatively charged than the outside, it reflected on the negative average voltage readings of the resting membrane.

The cortex consists of four sections, called "lobes". The frontal lobe is connected to reasoning, planning, speech, movement, emotions, and problem solving. The parietal lobe is associated with balance, recognizing, and movement. The occipital lobe is associated with vision. The temporal lobe is connected to hearing, memory, and speech. The cortex is highly wrinkled, making the brain more convenient, as this increases the brain's surface area, giving it more room for neurons. The cerebrum is divided into two hemispheres- the left hemisphere, and the right hemisphere. The right hemisphere is associated with creativity, and the left one is linked with logic. A bundle of nerve fibers, known as the corpus callosum connects these "hemispheres" (Brain Structures and their Functions). The cerebellum, which is also known as the "little brain", is similar to the cerebrum, since it also has two hemispheres and a highly folded surface. This part of the brain is linked with movement and balance. The cerebellum is assumed to be older than the cerebrum "evolutionarily" (Brain Structures and Their Functions). The brain stem controls basic life functions such as blood pressure, breathing, and heartbeat. Scientists say that the brain stem is the simplest part of the brain (Brain Structures and Their Functions).