1. Option A: Neurobiology & Behavior A2: THE HUMAN BRAIN USE THE INFO IN THE PRESENTATION TO COMPLETE A1 NOTES GUIDE INFORMATION TAKEN FROM: HL BIOLOGY 2 ND EDITION DAMON, MCGONEGAL, TOSTO, AND WARD BIOLOGY FOR THE IB DIPLOMA PREPARATION GUIDE WALPOLE

2. How does the brain develop from the neural tube? Anterior embryonic neural tube develops to become the brain Nerve cells migrate to the outer edge of the neural tube and causes the walls to thicken At 3 months in utero, the complete structure is in tact Neural tube develops into entire brain and spinal cord Rapid growth continues after this point Fibers of the nervous system form After birth, growth continues … up to 4 times bigger by age 6

3. Brain Development

4. Functions of different parts of the brain You should be able to label a diagram showing the main areas of the brain Hypothalamus Pituitary gland Medulla oblongata Spinal cord Cerbellum Cerebrum

5. Functions of different parts of the brain You should be able to label a diagram showing the main areas of the brain Hypothalamus – controls ANS, coordinates endocrine & nervous systems by regulating pituitary gland secretions Pituitary gland – posterior lobe stores & releases oxytocin and ADH from the hypothalamus; anterior lobe produces & secretes hormones (FSH, GH) Medulla oblongata – brain stem, controls automatic and homeostatic activities (breathing, swallowing, heart rate) Spinal cord Cerebellum – coordinates movement, posture, balance Cerebrum – coordination center for learning, memory, language, reasoning; receives info from the sense organs, and organizes motor functions

6. Spotlight on the Medulla Regulatory Center Swallowing center: coordinates the muscles of the mouth, pharynx, and larynx Breathing center: monitors level of carbon dioxide in the blood; if increased level the rate and depth of breathing increase Cardioaccelerator center: under the influence of exercise heart rate will increase by direct stimulation of the cardioaccelorator center

7. The ANS Autonomic Nervous System: controls involuntary processes in the body (swallowing, breathing, heart rate regulation) 2 divisions of the ANS (both receive impulses from the medulla) Sympathetic Nervous System – emergency responses, fight or flight, is excitatory in effect; ntm = noradrenaline Parasympathetic Nervous System – controls non-urgent events, relaxed situations, is inhibitory in effect; ntm = acetylcholine

8. Autonomic Nervous System

9. The ANS examples Parasympathetic System: Eye: causes contraction of circular muscles of the iris to control the pupil Heart: heart rate slowed down, stroke volume reduced as body relaxes Digestive System: blood vessels are dilated, increasing blood flow to the digestive system

10. The ANS examples Sympathetic System: Eye: causes contraction of radial muscles of the iris, dilating the pupil Heart: heart rate increased, stroke volume increased so that more blood can pump to the muscles Digestive System: blood flow to the digestive system is restricted as blood vessels constrict

11. Pupil Reflex

12. Cerebral Cortex Evolution in Humans Cerebral cortex of a human brain is the outer layer of the 2 cerebral hemispheres known as grey matter Controls functions like speech and decision making Only found in mammals Is folded so that its large surface area can fit into the skull

13. Cerebral Hemispheres Control higher order functions Learning, memory, recall, speech and emotions The right and left hemispheres contain different types of cells and different neurotransmitters Different areas of the cerebral cortex also have different functions

15. Left and Right sides of the brain Right hemisphere receives info from the left side of the body Left hemisphere from the right side of the body Both hemispheres process information, but with different functions Broca’s area: speaking and writing Wernicke’s area: understanding of language Left Hemisphere: communication (speaking, sign language) Right Hemisphere: understanding words, recognizing faces, spatial reasoning

16. Correlation between body and brain size E:S Ration: Weight of the brain compared to weight of the body E = brain weight S = body weight

17. Powering Brain Activity Very energy costly to fuel neurons and maintain membrane potentials of brain cells 25% of the body’s metabolic energy requirement goes to the brain Most of the energy supplied by aerobic respiration Active regions of the brain use more energy than non-active regions fMRI scanning can be used to identify areas of activity during different actitivies

18. Brain imaging technologies Neurobiology/Neuroscience: study of complex processing occurring in the nervous system Animal studies – behavior studies Brain injury studies – how different areas are affected when damaged by studying lesions MRI Scanning – locates abnormalities fMRI (functional magnetic resonance imaging) scans monitor brain activity from the blood flow to different areas

19. Brain Death That time when a physician has determined that the brain and brainstem have irreversibly lost all neurological function In a coma, there are signs that can be measured Testing for brain death: Movement of extremities Eye Movement Pupil Reflex Corneal reflex (blinking) Gag reflex Respiration response

20. Check for understanding 1.Name 2 higher order functions and the area of the brain which controls the functions. 2.If a person suffered an injury to Broca’s area of the brain, what functions might be affected? 3.Draw and annotate a diagram of the human brain. 4.Explain why brain metabolism requires a large input of energy.