The Brain
...pheral nervous system. The CNS is composed of the brain and spinal cord. The spinal cord also controls some behaviors on its own. Such behaviors are called reflexes. Three sorts of neurons are involved in reflexes. Sensory neurons transmit info from perimeter of body to CNS. Motor neurons send info from nervous system to muscles and glands. Inter-neurons connect sensory and motor neurons. The peripheral nervous system branches out from the spinal cord and the brain to your extremities. There are two major divisions. The somatic division and the autonomic division. The somatic division specializes in the control of voluntary movements. The autonomic division is concerned with the parts of the body that keep us alive. Two parts make up the autonomic division. The sympathetic division acts to prepare the body in stressful emergency situations. (fight or flight). The parasympathetic division acts to calm the body after the emergency has been resolved. Behavioral genetics studies the effect of heredity on behavior. Researchers are finding increasing evidence that cognitive abilities, personality traits, sexual orientation, and psychological disorders are determined to some extent by genetic factors. The Endocrine System: Of Chemicals and Glands The endocrine system is a chemical communication network that sends messages via the bloodstream. It secretes hormones that affect growth. A major component is the pituitary gland, which is found near, and regulated by, the hypothalamus. Also called master gland. The master gland affects growth. Others affect emotional reactions, sexual urges and energy levels. The Brain The Central Core: Our “Old Brain” The “old brain”, which controls basic functions such as eating and sleeping and is common to all vertebrates. The first part of the central core is the hindbrain, which contains the medulla, pons, and cerebellum. The medulla controls critical functions like breathing and heartbeat. The pons acts as a transmitter of motor info, coordinating muscles and movement between the left side and right side of the body. It also controls sleep. The cerebellum controls bodily balance. It’s also involved in several intellectual functions, ranging from the analysis of sensory info to problem solving. The reticular formation is the part of the brain from the medulla through the pons made up of groups of nerve cells that can activate other parts of the brain to produce bodily arousal. The thalamus, within the forebrain, acts as a busy relay station, mostly for info concerning the senses. The hypothalamus, located below the thalamus, maintains homeostasis and also regulates behavior critical for survival, such as eating, self-protection, and sex. The Limbic System: Beyond the Central Core The Limbic system is located outside the “new brain”. It controls eating, aggression, Reproduction, and the experience of pleasure. It also plays an important role in learning and memory. Because this part of the brain is not unique it is sometimes called the “animal brain”. Injury can produce striking changes in behavior. The Cerebral Cortex: Our “New Brain” The cerebral cortex (CC) is responsible for the most sophisticated info processing in the brain, like thinking, evaluating, and making complex decisions. Four major sections of the CC are frontal, parietal, temporal, and occipital. The sections are called lobes. The three major areas of the cortex are the motor areas, the sensory areas, and the association areas. The motor area is largely responsible for the body’s voluntary movements. Every portion of the motor area corresponds to a specific locale within the body. The sensory area corresponds to each of the senses, with the degree of sensitivity relating to the amount of tissue. The sensory area includes three regions. The somatosensory area is associated with the ability to perceive touch and pressure. An auditory area located in the temporal lobe is responsible for the sense of hearing. The visual area, located in the occipital area, operates analogously to the other sensory areas. The association area is the site of higher mental processes, such as thought, language, memory, and speech. Damage to this area can produce unusual behavioral changes. It can affect their ability to make moral judgments and process information. Apraxia occurs when an individual is unable to integrate activities in a logical manner. Aphasia is a problem with languag...