Unit 2: Body & Mind Ch.3: Biology and Behavior

I. The Nervous System The human nervous system is involved in thinking, dreaming feeling moving, and more. The nervous system regulates our internal functions. It is also involved on how we react to the external world. Learning and memory are made possible by the nervous system. The nervous system has 2 parts: the central nervous system and the peripheral nervous system. The central nervous system is made up of the brain and spinal cord. The peripheral nervous system is made up of nerve cells that send messages between the central nervous system and all the parts of the body.

A. Neurons Nerve cells, neurons, run through our bodies & communicate with each other. Neurons send & receive messages from the other structures in the body such as muscles & glands. –1. Components of a Neuron: Every neuron consist of a cell body, dendrites, & axon. –2.The Cell Body: Produced energy that fuels the activity of the cell. –3. The Dendrite: Branches out from the cell body and receives information from other neurons & passes the message through the cell body. –4. The Axon: Carries messages away from the cell body. –5.Myelin & Axon Terminals: Myelin (white/ fatty substance) insulates/ protects the axon. Axon terminals are located at the end of the axon and are smaller fibers that branch out.

B. The Communication Process Messages are sent from the axon terminals of one neuron to the dendrites of the other neurons. In order for a message to be sent from one neuron to another, it must cross the synapse. The synapse is a junction between the axon terminals of one neuron and the dendrites of another neuron. Messages travel in only one direction. Messages are received by the dendrites & travel through the cell body and the axon to the axon terminals.

C. Neurotransmitters: Chemical Messengers Neurons send messages across synapses through the release of neurotransmitters. Neurotransmitters are chemicals that are stored in sacs in the axon terminals. Dopamine is another neurotransmitter. It is involved primarily in motor behavior. A deficiency in dopamine levels plays a role in Parkinson's Disease. An excess of dopamine may contribute to the psychological disorder schizophrenia.

D. The Central Nervous System The Central Nervous System consists of the neurons of the spinal cord and the brain. The spinal cord extends from the brain down the back. It is a column of nerves about as thick a thumb and is protected by the bones of the spine. It transmits messages between the brain and the muscles/ glands throughout the body. The spinal cord is also involved in spinal reflexes. A spinal reflex is a simple, automatic response to something. Many of our simple actions are reflexive.

E. The Peripheral Nervous System The Peripheral Nervous System lies outside the central nervous system and is responsible for transmitting messages between the central nervous system and all other parts of the body. The two main divisions of the peripheral nervous system are the somatic nervous system and the autonatic nervous system.

F. The Somatic Nervous System The Somatic Nervous System transmits sensory messages to the central nervous system. It is activated by touch, pain, changes in temperature, and changes in body position. The somatic nervous system enables us to experience sensations of hot & cold & to feel pain & pressure. The SNS also alerts us that parts of the body have moved or changed positions. It sends messages to the muscles/ glans to help us maintain posture & balance.

G. The Autonomic Nervous System The word automatic means “occurring involuntarily” or automatically. The Autonomic Nervous System regulates the body’s vital functions, such as heartbeat, breathing, digestion, & blood pressure. Generally, we do not have to think about these activities, they occur automatically & are essential to keeping us alive. Psychologists are interested in the ANS because of its involvement in the experience of emotion. The response of the ANS is particularly important when a person experiences something stressful.

G. The Autonomic Nervous System... Continued! The ANS has two divisions, the sympathetic & parasympathetic nervous systems. These systems generally have opposing functions. The sympathetic nervous system is activated when a person is going into action, “fight or flight”. The SNS prepares the body by suppressing digestion, increasing the heart & respiration rates, & elevating blood pressure. The parasympathetic nervous system restores the body’s reserves of energy after an action had occurred. Heart rate & blood pressure normalize, breathing is slowed, & digestion returns to normal.

II. The Brain: Our Control Center Every person is unique in part because of the capacities for learning and thought made possible by the human brain. The accident Egyptians believed that a little person lived inside the skull & regulated behavior. Aristotle believed that the soul lived in the heart. B.F. Skinner believed the the English language still reflects the belief in the heart as the seat of good will. Today we recognize that the mind, or consciousness, dwells in the brain.

A. Parts of the Brain The human brain is composed of many parts that work together to organize our movements, create our thoughts, form our emotions, & produce our behaviors. Scientist have identified the localized functions of different parts of the brain. The brain is divided into 3 sections: the hindbrain, the midbrain, & the forebrain. The hindbrain is the lower portion of the brain and is involved in many vital function such as heart rate, respiration, & balance. The midbrain includes areas that are involved in vision & breathing. The forebrain, in the front area of the brain, is involved in complex functions such as thought & emotion.

1. The Hindbrain The medulla, the pons, & the cerebellum are important structures of the hindbrain. The medulla: helps regulate/ maintain vital functions such as heart rate, blood pressure, & breathing. The pons: located in front of the medulla, regulates bodily movement, attention, sleep, & alertness. The cerebellum: rests under the large part of the brain, & is involved in balance & coordination.

2. The Midbrain The midbrain is located between the hindbrain & the forebrain. Areas within the midbrain are involved in vision & hearing. The midbrain contains the reticular activating system: this is important for attention, sleep, & arousal.

3. The Forebrain Four key areas of the forebrain are the thalamus, the hypothalamus, the limbic system, & the cerebrum. The thalamus is a critical structure of the brain because it serves as a relay station for sensory stimulation. The thalamus transmits sensory information, such as pain, to the areas of the brain that interpret and respond to the information. The thalamus also relays sensory input from the eyes and ears to the appropriate parts of the brain for interpretation of the input..

Hypothalamus lies below the thalamus, it is tiny but important because it is involved in many aspects of behavior & physiological functions. Also vital to regulating body temperature, storage of nutrients, & motivation/ emotion. It is also involved in hunger, thirst, sexual behavior, caring for off spring & aggression. The limbic system: forms a fringe along the inner edge of the cerebrum. It is involved in learning/ memory, emotion, hunger, sex, & aggression. The cerebrum: (Latin for “brain”): accounts for 70% of the weight of the brain. The surface of the cerebrum is wrinkled w/ ridges & valleys, this surface is the cerebral cortex, the cortex is involved in memory, language, emotions, complex motor functions, & perceptions

B. The Cerebral Cortex: What makes us unique The cerebral cortex is composed of 2 sides: a left & right hemisphere. The structure that connects the 2 hemispheres is the corpus callosum. Information received by one side of the body is transmitted to the opposite hemisphere of the brain. The corpus callosum aids in getting information from one side of the brain to the other. Each hemisphere of the cerebral cortex is divided into 4 parts, or lobes: The frontal lobe (behind the forehead), parietal lobe (top/ rear of the head), the temporal lobe (off to the side, behind your ears), & the occipital lobe (back of the head).

1. Senses & Motor Behavior The Occipital Lobe: Contains the primary visual area of the cerebral cortex. The Temporal Lobe: Contains the auditory area of the cortex. Sounds are relayed from the ears to the thalamus to the auditory area. When this occurs we hear sounds. Frontal Lobe: Motor portion of the cortex. Parietal Lobe: Primary sensory area.

2. Association Areas Much of the cerebral cortex is composed of areas that involve sensory and motor functions, these areas help shape information into something more meaningful. Association areas in the frontal lobe (near the forehead) is the brain’s executive center. This is the area of the brain we use to solve problems, make plans and decisions. Association areas also provide the core of your working memory.

2. Language Abilities For nearly all right- handed people, language functions are based in the the left hemisphere. Language functions are also based in the left hemisphere of about 2 out of 3 left handed people. Two language areas: Broca’s area (located in the frontal lobe) & Wernicke’s area ( located un the temporal lobe, pieces together sight & sound).

3. Left vs. Right Hemispheres The same hemisphere that contains most language functions is usually more involved in logic, problem solving, & mathematical computation than the other hemisphere. People who are said to be more logical are said to be more “left –brained”, people who are particularly creative are more “right- brained”.

III. The Endocrine System The Endocrine System contains glands that secrete hormones into the bloodstream. Hormones have specific receptor sites. Hormones are produced by certain glands: the pituitary gland, the thyroid gland, the adrenal gland, and the testes and the ovaries.

A. The Pituitary Gland The pituitary gland, lies below the hypothalamus, is the size of a pea= “The Master Gland”, controls growth and development. Specifically producing oxytocin, which stimulates labor in pregnant women.

B. The Thyroid Gland The thyroid gland produces thyroxin, which effects the body’s metabolism (the rate of converting food into energy). Too little= hypothyroidism, too much= hyperthyroidism.

C. The Adrenal Glad The Adrenal Glands, located above the kidneys. The outer layer (the cortex) secretes cortical steroids, which increase resistance to stress & promote muscle development. Also causes the liver to release sugar, making energy available for emergencies. The Adrenal glad also produces adrenaline & noradrenaline

D. The Testes & the Ovaries Testes= glands in males Ovaries= glands in females. Produce testosterone, progesterone, & estrogen.

1. Testosterone Male sex hormone (similar to a steroid), females produce small amounts of this hormone. Produced in the testes in males. Produced in the ovaries in females. Testosterone, in prenatal development, influences the sex organs. At 8 weeks gestation, testosterone is release, resulting in the creation of male sex organs. During adolescence, aids growth of muscle & growth development as well as primary (directly involved in reproduction) & secondary sex characteristics.

2. Estrogen & Progesterone Both are female sex hormones, also small amounts found in males. The ovaries produce both hormones in females. Estrogen is produced in small amounts in the testes in males. Estrogen fosters the development of primary & secondary sex characteristics in women. Progesterone: stimulates the growth of female reproductive organs, & prepares the body for pregnancy. Progesterone & Estrogen= regulate the menstrual cycle