The Biological Perspective

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The Biological Perspective

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1. The Biological Perspective Chapter 2

2. To Survive… Sensing events requires that a stimulus activates a receptor Processing events takes place in the brain Responding to events occurs when the brain sends messages to the muscles *Interrelated processes necessary for human survival

3. Neuron Basic nerve cell that makes up the nervous system, sending & receiving messages within the system Made up of dendrites, cell body (soma) and axon

4. Components of the Neuron Dendrites “Branches” that receive information from the receptors & other neurons. Soma Cell body which contains the nucleus and relays neural signals Axon long part of the neuron that transmits signals to other neurons, muscles, & glands. ACTIVITY: assign 7 different tasks to 7 different groups in class, have them prepare an in-class presentation Dendrites and cell body; axon, myelin sheath, and terminal buttons; synapse and neurotransmitters; serotonin and dopamine; Ach and Norepinephrine; clearing the synapse; drug action ACTIVITY: assign 7 different tasks to 7 different groups in class, have them prepare an in-class presentation Dendrites and cell body; axon, myelin sheath, and terminal buttons; synapse and neurotransmitters; serotonin and dopamine; Ach and Norepinephrine; clearing the synapse; drug action

5. Components of the Neuron Synaptic Knob (AKA terminal) Button at the end of the axon where neurotransmitters are stored. Myelin Sheath A fatty covering to insulate, protect, and speed up transmission of the neural impulse.

6. Neurons Basic cells of the nervous system

7. Synapse & Neurotransmitters Synapse: The gap between two neurons Terminal button sends a signal Dendrite receives a signal Neurotransmitters: Vesicles hold NT’s to transport signal across the synapse Through excitation or inhibition NT’s activate cells

10. Major Neurotransmitters Acetylcholine (Ach): enables muscle action, learning, & memory With Alzheimer’s disease, Ach-producing neurons deteriorate Dopamine (DA): influences movement, learning, attention, & emotion Decreases of DA associated with Parkinson’s Excess DA receptor activity linked to schizophrenia If Ach transmission is blocked, muscles cannot contract. If Ach transmission is blocked, muscles cannot contract.

11. Major Neurotransmitters Serotonin (5-HT): affects mood, hunger, sleep, & arousal Undersupply linked to depression. Prozac & other antidepressant drugs raise serotonin levels. Norepinephrine (NE): helps control alertness & arousal Undersupply can depress mood and energy

12. Clearing the Synapse Neurotransmitter is either taken back into the neuron (reuptake) or eliminated by an enzyme (breakdown)

13. The Nervous System The activities of sensing, processing, and responding are coordinated and controlled by the nervous system. Two major divisions: Central Nervous System Peripheral Nervous System

14. Central Nervous System Brain Spinal cord (2 sections) “outer” section is the message freeway of nervous system “inner” section is a kind of “brain” responsible for certain reflexive actions Afferent (sensory) neurons: from senses to spinal cord Efferent (motor) neurons: from spinal cord to muscles/glands Interneurons: connects them both

15. Peripheral Nervous System (PNS) All nerves & neurons that are not contained in the brain & spinal cord, run through the body itself. PNS has 2 divisions Somatic nerves that carry information from the senses to the CNS & from the CNS to the voluntary muscles of the body. Autonomic nerves that control all of the involuntary muscles, organs, & glands.

16. Peripheral Nervous System Somatic Division: division consisting of nerves that carry information from the senses to the CNS & from the CNS to the voluntary muscles of the body. Sensory pathway Motor pathway Voluntary muscles that can move at will or respond to reflexes. Examples: Walking, raising your hand, smelling a flower

17. Peripheral Nervous System Autonomic Division: division of the PNS consisting of nerves that control all of the involuntary muscles, organs, & glands. Two divisions: Sympathetic division part of the ANS that is responsible for reacting to stressful events and bodily arousal, prepares the body for “fight or flight”. Parasympathetic division returns the body to homeostasis, the “eat-drink-and-rest system” Pupils seem to get bigger, heart pumps faster and harder drawing blood away from nonessential organs, skin becomes pale. Breathe faster to supply more oxygen. Digestion and excretion of waste slow down, saliva production decreasesPupils seem to get bigger, heart pumps faster and harder drawing blood away from nonessential organs, skin becomes pale. Breathe faster to supply more oxygen. Digestion and excretion of waste slow down, saliva production decreases

18. Brain: A Closer Look Why is the brain so wrinkly? Surface area – roughly the size of a newspaper page (brain flattened out).Surface area – roughly the size of a newspaper page (brain flattened out).

19. Investigating Brain Functioning Phrenology: reading bumps on the skull Case study: Phineas Gage injury to left frontal lobe. Electroencephalography (EEG): monitors & records electrical activity of the brain. Computerized Brain Imaging: SPECT scan, CAT, MRI Phrenology: pseudoscience phrenology, science of the mind. Developed by Franz Joseph Gall – brain like a muscle, exercise it and it grows larger. BUMPS = well developed skills & personality characteristics. **Believed skills & characteristics could be localized in certain areas of the brain.Phrenology: pseudoscience phrenology, science of the mind. Developed by Franz Joseph Gall – brain like a muscle, exercise it and it grows larger. BUMPS = well developed skills & personality characteristics. **Believed skills & characteristics could be localized in certain areas of the brain.

20. Peeking Inside the Brain Computed tomography (CT) - brain-imaging method using computer controlled X-rays of the brain. Positron emission tomography (PET) - brain-imaging method in which a radioactive sugar is injected into the subject and a computer compiles a color-coded image of the activity of the brain with lighter colors indicating more activity.

23. Cerebral Cortex Lobes Frontal Lobe: contains the motor cortex & Broca’s area Function: involved in speaking & muscle movements, making plans, judgments, personality. Broca’s aphasia - condition resulting from damage to Broca’s area (usually in left frontal lobe), causing the affected person to be unable to speak fluently, to mispronounce words, and to speak haltingly. Parietal Lobe: contains the sensory cortex Function: receives sensory input for touch & body position. Parietal: sense of touch & body position Parietal: sense of touch & body position

24. Cerebral Cortex Lobes Temporal Lobe: speech, hearing, & some visual information processing Wernicke’s aphasia - condition resulting from damage to Wernicke’s area (usually in left temporal lobe), causing the affected person to be unable to understand or produce meaningful language. Occipital Lobes: located in the back of the brain, responsible for processing visual stimuli. Contralateral organization = right visual field sent to left occipital lobe, & vice versa Wernicke’s area = in most people it is located in the left temporal lobeWernicke’s area = in most people it is located in the left temporal lobe

27. EXTRA SLIDES After neurotransmitter & drug action slide

28. Neurotransmitters & Drug Action Agonists enhance the operation of neurotransmitters (caffeine). Antagonists block the operation of neurotransmitters. Neuromodulators are substances that do not directly activate ion-channel receptors but that, acting together with neurotransmitters, enhance the excitatory or inhibitory responses of the receptors.

29. The Neural Signal Neuron’s resting state means more negative ions inside membrane. Depolarization or hyperpolarization change the negative charge. Depolarization & excitatory synapses Action potential describes neuron’s all-or-none firing Refractory period can be absolute or relative Hyperpolarization & inhibitory synapses

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