HESI A2 Exam: Nervous System
• What involves the "fight or flight" response, such as an increase in adrenaline during a heated argument?
• What is the thin layer of gray matter that covers the cerebrum?
• What receives impulses from the interneurons and transmit them away from the cell body?
• What regulates breathing, heart rate, and swallowing?
• Which lobe processes data related to movement, taste, temperature, and touch?
Central Nervous System
The medulla, the cerebrum, and the cerebellum make up the central nervous system. The central nervous system is the brain and the spinal cord.
The cerebrum is covered by a thin layer known as the cerebral cortex. The cerebral cortex is a thin layer of gray matter. The cerebrum controls speech, thought, memory, learning and language.
The medulla controls autonomic and homeostatic functions such as breathing and blood pressure.
The cerebellum regulates muscle coordination and balance.
The pons and the medulla oblongata are parts of the brain stem. Information from the body is sent to the brain through the brain stem, and vice versa.
The midbrain integrates sensory signals and orchestrates responses to these signals. The midbrain is an important part of vision and hearing.
The hindbrain includes the medulla oblongata, cerebellum, and pons.
The forebrain includes the cerebrum, thalamus, and hypothalamus.
Other Important Systems
The sympathetic system is generally excitatory and involves "fight or flight." The parasympathetic system is the opposite, it has a calming effect such as decreased heart rate. The sympathetic and parasympathetic nervous systems are each part of the autonomic nervous system, which controls involuntary muscles.
The motor system controls voluntary muscles. A motor neuron (or motoneuron) is a neuron whose cell body is located in the spinal cord and whose fiber (axon) projects outside the spinal cord to directly or indirectly control effector organs, mainly muscles and glands.
The sensory system carries information from sensory receptors and nerve endings.
The peripheral nervous system includes all the nerves outside the central nervous system, including nerves under conscious control (somatic) and nerves outside conscious control (autonomic).
Lobes
The parietal lobe processes data related to movement, taste, temperature, and touch.
The frontal lobe is related to voluntary movement.
The occipital lobe is responsible for vision and the temporal lobe is for comprehension, emotion, language, memory, and sensory input.
Neurons and Nerves
Neurons transmit signals throughout the body.
Interneurons create neural circuits, enabling communication between sensory or motor neurons and the central nervous system (the brain and spinal cord).
Afferent nerves bring signals from the sensory organs and muscles to the CNS.
Efferent nerves bring signals from the CNS to the sensory organs and muscles.
Sensory neurons are nerve cells within the nervous system responsible for converting external stimuli from the organism's environment into internal electrical impulses. For example, some sensory neurons respond to tactile stimuli and can activate motor neurons in order to achieve muscle contraction.
Dendrites, Axons and Other Stuff to Know
Dendrites receive impulses from the interneurons and transmit them towards the cell body.
The axon transmits the impulses away from the cell body. The cell body contains the nucleus of the neuron. The axon terminates at the synapse. Axons carry action potentials in the direction of synapses. Messages are communicated between the brain and the muscles through electrical signals (action potential). These action potentials travel along the axon.
Myelin is a type of coating for the nerves and ensures transmission of information.
A synapse allows a neuron to send a chemical signal to another neuron. A synapse is a space between a terminal branch of a neuron and another neuron. A neurotransmitter, such as dopamine, is released at the synapse.
One of the main functions of the hypothalamus is that it connects the nervous system to the endocrine system. This allows the hypothalamus to regulate our body’s temperature. The hypothalamus also aids in certain metabolic processes, and helps to regulate the autonomic nervous system.
The primary job of the thalamus is to inform the cerebral cortex of any sensory or motor stimuli. The thalamus also helps to control sleep, and aids in keeping us awake and alert.
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