Nervous System, the Brain, and the Sensory Organs

Transcription

1 Nervous System, the Brain, and the Sensory Organs Functions of the Nervous System 1. Sensory input is the gathering information to monitor changes ( ) occurring inside and outside the body 2. Integration occurs when your body processes and interprets input and decides if action is needed. 3. Motor output is a response to integrated stimuli that activates or Structural Classification of the Nervous System The central nervous system (CNS) is comprised of the and. The peripheral nervous system (PNS) is comprised of the nerves the brain and spinal cord. Functional Classification of the PNS The sensory (afferent) division consistes of nerve fibers that carry information the CNS. The motor (efferent) division consists of the nerve fibers that carry impulses the CNS; there are subdivisions: the nervous system, which is the part of the part, and the nervous system, which is the part. Organization of the Nervous System The nervous system s basic unit is the (Nerve Cell). These cells are specialized to messages. The neuron has 2 major regions: the cell body that consists of the, a large, and is the center of the cell, and the, which are the fibers that extend from the cell body ( - which conduct impulses toward the cell body, and - which conduct impulses away from the cell body). (covering)

2 Neuron Cell Body Location Most are found in the nervous system matter consists of cell bodies and (not insulated) fibers Nuclei are clusters of cell bodies within the matter of the CNS are collections of cell bodies outside the CNS Functional Classification of Neurons There are 2 types of neurons. (afferent) neurons carry impulses from the receptors. They are the (skin) sense organs. The detect stretch or tension in the skin. (efferent) neurons carry impulses from the. The Reflex Arc A reflex is a,, and responses to stimuli. A reflex arc is the direct route from a neuron, to an, to an, which will be a muscle or gland. Somatic reflexes result in the activation of.

3 Types of Reflexes and Regulation Simple Reflex Arc Autonomic reflexes are involved in muscle regulation, such as and regulation, regulation of, and system regulation. Central Nervous System (CNS) The CNS develops from the neural tube, which becomes the and. The opening of the neural tube becomes the (brain chambers). There are chambers within the brain that are filled with fluid. There are 4 regions of the brain. They are,,, and. Each of these regions is subdivided into.

4 Cerebral Hemispheres ( ) are paired (left and right) superior parts of the brain that include half of the brain mass, has its surface made of (gyri) and (sulci), and has that divide the cerebrum into lobes. There are surface lobes of the cerebrum; they are the,,, and lobes. There are many specialized areas of the brain. Three of these are (1) the sensory area receives impulses from the body s sensory receptors, (2) the motor area sends impulses to skeletal muscles, and, (3) the area is involved in our ability to speak. Specialized Areas of the Cerebrum The cerebral areas involved in special senses are the area (taste), the (sight) area, (hearing) area, and area (smell). Interpretation areas of the cerebrum The brain has many specialized regions with very specific jobs. Three of these are the region, the region, and the region.

5 The brain stem attaches to the _. It is divided into 3 regions: (1), (2), and. The midbrain is composed of of nerve fibers. It has the reflex centers for and. It also contains the cerebral aquaduct which connects the 3 rd and 4 th to allow flow of. The pons is the bulging part of the brain stem, mostly composed of fiber tracts, that includes nuclei involved in the control of. The medulla oblongata is the part of the brain stem, that merges into the _, includes important fiber tracts, and contains important control centers for control, regulation,,, and. The has 2 hemispheres with convoluted surfaces (folds). It provides coordination of body movements.

6 Protection of the CNS The CNS is protected by multiple levels of protection. These include and,, fluid, and the barrier. There are many conditions that impact the brain. These include Traumatic Brain Injuries (TBI), Cerebrovascular Accidents (CVA), Alzheimer s Disease (which is actually a disorder), and Spinal Cord Injuries. TBIs include (1), these are slight or mild brain injury with bleeding & tearing of nerve fibers where recovery is likely with some memory loss; and, (2), which are a more severe TBI with nervous tissue destruction where the nervous tissue does not regenerate. CVAs include (1) where there is swelling of the brain from an inflammatory response that may compress and kill brain tissue; and (2) that results in collection of blood below the dura (this is a bruise on the brain). These are commonly called a because they result of a blood vessel supplying a region of the brain causing the brain tissue supplied with oxygen from that blood source to. There will be loss of some functions or death may result. Alzheimer s Disease is a progressive brain disorder that is mostly seen in the, but may begin in middle age. It results in structural changes in the brain that include abnormal deposits and twisted fibers within neurons. Victims experience,,, and ultimately, and. SCJs extend from the _ to the region of the spinal cord. Below T12 is the (a collection of spinal nerves). Enlargements occur in the and regions. These may result in great pain, loss of mobility, or paralysis.

7 The Peripheral Nervous System consists of nerves (bundles of ) and ganglia the CNS. Neuron fibers are bundled together by tissue that strengthens and insulates the neurons. Spinal nerves always come in at the level of each vertebrae. The spinal nerves connect the CNS to all of the other areas of the body. The Autonomic Nervous System is the branch of the nervous system consisting of only nerves. It is divided into two divisions: the division and the division. The sympathetic fight-or-flight division is the to an unusual that takes over to neural activities. You can easily remember this division as the E division =, _,, and. The division housekeeping activities helps the body energy by the necessary daily body functions. You can easily rememeber this division as the D division -,, and (urination). EXAMPLE of Response blinking to remove dust EXAMPLE of Response crying due to stress

8 Comparison of Somatic and Autonomic Nervous Systems The eye is the organ of. It has a complex structure consisting of a lens that focuses light on the, which is covered with two basic types of light-sensitive cells- and color-sensitive cells -. The cone cells are sensitive to color and are located in the part of the retina called the, where the light is focused by the. The rod cells are not sensitive to color, but have sensitivity to light than the cone cells. Rods are located around the fovea and are responsible for (side) vision and vision. The eye is connected to the brain through the nerve. The point of this connection is called the "_" because it is insensitive to light. Experiments have shown that the back of the brain ( ) maps the visual input from the eyes. Being nearsighted or farsighted depends on the of your eye. People with blue eyes all share a common. Your eyes actually see everything upside down, but your brain sorts it out and flips it over for you. Your eyes can get sunburned too. We blink times per day. 20/20 vision isn't perfect vision, it's just. The human eye can detect over different colors. The ear is the organ of. The outer ear protrudes away from the head and is shaped like a to direct sounds toward the membrane, which transmits vibrations to the ear through a series of small bones in the middle ear called the, and. The inner ear, or, is a spiral-shaped chamber covered internally by nerve fibers that react to the vibrations and transmit impulses to the brain via the nerve. The brain combines the input of our two ears to determine the and of sounds.

9 Your ears contain the three bones in the human body: the malleus, incus, and stapes. Ears help the body maintain. The outside of the ear is called the which acts as a funnel, collecting and amplifying sound for the inner ear. Your ability to hear high frequencies deteriorates as you get older, because the hair cells closest to your outer ear begin to break down. Sound travels at roughly miles per hour through our atmosphere. Sound travels faster through more dense substances. is used to catch dirt and debris. The hardest bone in the human body is the bone and it shapes the inner ear where its shape helps process sounds in the ear. The receptors for taste, called taste buds, are situated chiefly in the Label this diagram. tongue, but they are also located in the roof of the mouth and near the pharynx. They are able to detect six basic tastes:,,,, astringent and pungent. The tongue also can detect a sensation called "umami from taste receptors sensitive to amino acids (pungent). Generally, the taste buds close to the of the tongue are sensitive to sweet tastes, whereas those in the of the tongue are sensitive to bitter tastes. The taste buds on and on the of the tongue are sensitive to salty and sour. Your taste buds have a lifespan that can last from days to weeks. It is possible to kill your taste buds by burning your tongue, but they (grow back) rather quickly. However, smoking can actually reduce taste bud pods (called papillae) and therefore dull your taste buds more. Taste buds are made up of, which are microscopic hairs that send signals to the brain to tell us how to process and identify how things taste. Your taste buds need the help of your nose s senses to send the correct message to the brain about how something tastes. The flavor of something is determined by the taste and the smell senses. When you smell an odor you are also it. salty salty astringent bitter bitter bitter pungent sour sour sweet The nose is the organ responsible for the sense of. The cavity of the nose is lined with membranes that have smell receptors connected to the nerve. The smells themselves consist of of various substances. The smell receptors interact with the molecules of these vapors and the sensations to the brain. The nose also has a structure called the organ whose function is being sensitive to pheromones that influence the reproductive cycle. The sense of smell is sometimes temporarily lost when a person has a. The sense of smell comes about through the stimulation of specialized cells in our nasal cavities cells that are similar to the sensory cells of the of invertebrates (like cockroaches and lobsters). The human olfactory system works when odorant bind to specific sites on the olfactory, which are used to detect the presence of smell. It all comes together at the, a structure which transmits signals to the olfactory bulb a part of the brain directly above

10 the nasal cavity and below the lobe. The end result is the (individualized) experience we call smell. The smell receptors are sensitive to types of sensations that can be characterized into 10 categories: (e.g. florals and perfumes) (all non-citrus fruits) (e.g. lemon, lime, orange) (e.g. pine or fresh cut grass) (e.g. ammonia, bleach) (e.g. chocolate, vanilla, caramel) (e.g. eucalyptus and camphor) (e.g popcorn, peanut butter, almonds) (e.g. blue cheese, cigar smoke) (e.g. rotting meat, sour milk) The sense of is distributed throughout the body. Nerve endings in the skin and other parts of the body sensations to the brain. Some parts of the body have a larger number of nerve endings and, therefore, are sensitive. Four kinds of touch sensations can be identified:,,, and. on the skin magnify the sensitivity and act as an early warning system for the body. The sense of touch is the first to develop in humans at about weeks into the gestation (formation in the uterus) period. Touch stimulates the brain to release. The skin is your body s largest organ and contains more than sensory receptors. Among the body s most sensitive areas are the, the back of the, the, and the of the feet. The least sensitive area of your body is the of your back. Being touched can stress, by lowering levels of hormones like, which can reduce and. is the body s warning system and that s why people have more receptors for pain than for any other sensations. perceive sensations related to temperature, but they may be stimulated when the surface of the skin drops below F (which is why your skin starts to feel numb in icy temperatures) or rises above F (at which point pain receptors take over to avoid burns). Adipose tissue is another name for this layer because it is composed of lipids (fats).