Module 6: Nervous System Flashcards
What does the central nervous system (CNS) consist of?
The CNS is made up of the brain and the spinal cord.
What does the peripheral nervous system (PNS) consist of?
The nerves outside the CNS that go to muscles and organs like the heart are considered part of the PNS. The PNS can be divided into the somatomotor (going to skeletal muscles) and autonomic (going to other organs) nervous systems.
What is the basic structure of the brain?
- There are two cerebral hemispheres (left and right). The left hemisphere sends signals to activate muscles on the right side of the body. Sensory information from the right side of the body travels to the left hemisphere.
- Each cerebral hemisphere can be divided into four lobes: frontal, parietal, occipital and temporal
- The brain stem, which controls some of the most basic functions of the body like heart rate and respiration is made up of the midbrain, pons, and medulla oblongata. The medulla is continuous with the spinal cord.
- At the back of the brain and just above the brain stem is the cerebellum, which is mainly responsible for coordinated movement.
- The diencephalon consists of the thalamus and the hypothalamus.
- There are many bumps (gyri) and dips (sulci) on the surface of the brain. These folds are most prominent in humans and increase the surface area of the brain. However, the locations of the gyri and sulci are not quite consistent between individuals.
What is the frontal lobe?
The frontal lobe has the primary motor cortex which processes input from skeletal muscles throughout the body. The motor association area (premotor cortex) and the prefrontal cortex integrate movement information with other sensory inputs to generate perception of stimuli.
The primary motor cortices are at the posterior end of the frontal lobe and they process information relating to skeletal muscle movement. When electrically stimulated, this region will cause a specific muscle to contract.
What is the parietal lobe?
The parietal lobe contains the primary somatosensory cortex, which receives input from the major sense organs (the skin, musculoskeletal system and taste buds). The association areas of the parietal lobe integrate sensory information with other association areas of the cortex to form meaningful perceptions.
The primary somatosensory cortex is located at the anterior end of the parietal lobe and receives sensory information from the opposite side of the body. The sensations of touch, temperature, pain and vibration are processed here.
What is the temporal lobe?
The temporal lobe contains the primary auditory cortex and auditory association areas, which receive and process signals from the auditory nerve and integrate them with other sensory inputs. Other portions of the temporal lobe are involved in olfaction (smell) and in mediating short-term memory storage and recall.
What is the occipital lobe?
It is the area of the cerebral cortex responsible for vision. It contains the primary visual cortex which receives input directly from the optic nerve, as well as visual association areas that further process visual information and integrate it with other sensory inputs.
What is the cerebellum?
The cerebellum processes sensory information and coordinates the execution of movement in the body. It is the structure with the largest number of neurons in the brain and the cerebellum receives input from somatic receptors, receptors for equilibrium and balance, as well as motor neurons in the cortex.
What is the corpus callosum?
A dense bundle of nerve fibers that serves as a pathway and connection between the two cerebral hemispheres. This connection allows the brain to integrate sensory and motor information from both sides of the body, and to coordinate whole-body movement and function.
What is the pituitary gland?
The pituitary gland primarily regulates other endocrine organs. The anterior pituitary is derived from epithelial tissue of the pharynx while the posterior pituitary derives from neural tissue of the hypothalamus. Anterior pituitary hormones include LH, FSH, ACTH, TSH, GH, and prolactin. The posterior pituitary releases the hormones vasopressin and oxytocin. Pituitary function is regulated by the hypothalamus.
What are the pons?
The primary function of the pons is to act as a relay station for transferring information between the cerebellum and the cerebral cortex. Along with its centers in the medulla, the pons also coordinates and controls breathing.
What is the diencephalon?
It consists of two major areas:
- The thalamus receives sensory input as it travels from the spinal cord and integrates sensory information before sending it to the cortex.
- The hypothalamus controls a variety of endocrine functions (body temperature, thirst, food intake, etc.), mainly through directing the release of hormones.
What is the midbrain?
The midbrain bridges the lower brainstem with the diencephalon. Its primary function is controlling eye movements, and it also exerts control over auditory and visual motor reflexes.
What is the medulla?
It is a portion of the brainstem that has primary control over involuntary functions such as breathing, blood pressure and swallowing. It is also here that fibers from the corticospinal tract, which originate in the motor cortex, cross over to the opposite side of the spinal cord to innervate muscles on the opposite side of the body.
What are the optic nerves?
Optic nerves from each eye meet at the optic chiasma where they cross over and continue on as optic tracts to the lateral geniculate bodies of the thalamus. From there, axons extend to their respective hemisphere on the primary visual area of the occipital lobe.
