The Biological Foundations of Behavior The nervous system: the most complicated system in human body where billions of interconnected cells radiate all over the body. Specialized Cells of nervous system include: 1. Receptor cells: Embedded in sense organs, (seeing – hearing – smelling – tasting – touching). receive various types of stimulation from environment, which are then transmitted to the brain. 1

2. Effector cells: Brain sends motor signals to the effector cells embedded in muscles and glands. 3. Neurons: Specialized to conduct signals from one part to another, (connect receptor cells to effector cells). 4. Nerve: long, fibrous parts of many neurons bundled together, and run through the bodies. 2

Division of nervous system: 1- Central Nervous System (CNS): consists of brain and spinal cord. 2-Peripheral Nervous System (PNS): Branching out from the CNS and leading to all parts of the body. Neurons from PNS convey signals from receptor cells to the spinal cord and brain (afferent pathway). neurons transmit messages from brain and spinal cord to effectors cells (efferent pathway). 3

*Efferent pathway has two divisions: Somatic nervous system: it controls actions that are under voluntary control. Autonomic nervous system: control muscles of internal organs ( the heart, intestine, blood vessels) and glands, usually automatic or involuntary. 4

Autonomic nervous system has two divisions: (opposite effects). a. Sympathetic nervous system: In emergency situations as meeting a snake, lead to increase blood sugar, heart rate and blood pressure, and inhibiting digestion (Fight- Flight- Fright response) 5

b. Parasympathetic Nervous System: -Dominates under relaxation conditions and tends to conserve body's energy. -After eating large meal, it works to aid digestion, at the same time decreasing heart rate and blood flow to skeletal muscles 6

Division of the nerves system (Look in your book please) 7

Composition of neuron cell: A- Cell body: the life support center of the cell. B- Dendrites: receive messages transmitted from other neurons (antenna of neurons). C- Axons: carries neural signals to affect the muscle fibers 8

Types of neuron 1- Sensory neurons: carry information form sense organs to the brain & spinal cord. 2-Motor neurons: carry signals from brain and spinal cord to muscles and glands. 3-Inter-neurons: connect neuron to other neurons. 9

Brain Structurally the brain is divided into the cerebrum, cerebellum, brain stem, and limbic system. (1) CEREBRUM The cerebrum is divided into two hemispheres: (2) CEREBELLUM: center for coordination of movements and postural adjustments. 10

(3) Brain Stem: Includes the midbrain, Pons, and medulla oblongata. Medulla oblongata: contains vital centers for respiration and cardiovascular functions. (4) Limbic System: located above the brain stem that includes: - The hypothalamus is involved in temperature regulation, appetite control, endocrine function…etc. Hippocampus is involved in emotional arousal and memory. 11

Neurotransmission: - Neurons communicate information with one another by sending electrochemical messages from neuron to neuron. Neurotransmitters: - Chemical substances manufactured in the neuron, aid in the transmission of information throughout the body. 12

Major Neurotransmitters in Psychology 1-Dopamine:(excitatory). -Control of complex movements, motivation, cognition, and regulation of emotional responses. 2 Nor epinephrine (Noradrenalin) : plays a role in changes in attention, learning and memory, sleep and wakefulness, and mood regulation. 13

Major Neurotransmitters in Psychology…cot. 3- Epinephrine (adrenaline): - Controls fight-or-flight response in anxiety disorders. 4- Serotonin: (inhibitory): - Control of sleep,wakefulness, emotions and sexual behavior. 14

Major Neurotransmitters in Psychology…cot. 5- Gamma-Amino Butyric Acid (GABA): - Drugs that increase GABA function used to treat anxiety and induce sleep. 6- Acetylcholine: (excitatory or inhibitory). - affect the sleep/wake cycle and to signal muscles to become active. 15

Sensation and Perception Sensation: (The process where by stimulation of receptor cells like eye, nose, ear …etc., send nerve impulses to the brain, where they register a touch, sound, color …etc). Perception: - (process where the brain interprets sensation giving them order and meaning). 16

Sensation and Perception…cont. - Without sensation: perception couldn’t occur, without perception sensations without meaning. - Impaired perception cause (illusion). 17

Stimulus (Any form of energy (sound, light, heat, and pressure) to which an organism is capable of responding). Stimuli and sensation have a cause and effect relationship. 18

Factors affects stimulus detection: - (1) The intensity of stimulus. - (2) Background noise interfere with stimulus detection. - (3) Motivation (rewards or punishments). -(4) Prolonged constant stimulation: lead to sensory adaptation. 19

How do perceptual processes develop? 1. Empiricist view of perceptual development: - Babies enter the world with little or no ability to see depth, form, and perceptual constancy’s. - Infants learn adult like perceptions on the basis of cues the environment provides. 20

2. Nativist view of perceptual development: Not all perceptual process are learned, some arise from the way our sensory system work, e.g. feeling of hunger or diaper wetting. 21

3- Interactionism view of perceptual development: - Through the interaction of both biological factors & experience perceptual process develop. - what we see, hears, feel, and so forth, is partly the results of how our sensory systems are programmed and partly the result of what we are exposed to. 22

Expectations and perceptions Psychologists have studied two ways in which learning and experience mold our expectations which in turn shape our perception 23

1-Perceptual set: - A frame of mind that “sets” a person to perceive things in a certain way. -We perceive what we think we should perceive. - Perceptual sets establish expectations that guide our perception 24

* Example ( illusion ): person who was bitten by snake in the dark in specific area. The sight of snake become a perceptual set for this person. When he see a rope in the same area under similar conditions establish an expectation of snake this expectation guide his perception, so he perceive the rope as a snake. 25

2- Perceptual schema: Mental representation of objects and events against which incoming data are compared and interpreted. -General knowledge of the world in the form of schemas also shape our expectations and hence our knowledge. - Example: How quickly people process the information in photos with a real world scenes as a city street or a kitchen. When people view such scenes for only a second, they can remember almost half of the objects that scenes contain. 26