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The Brain

I-XII pairs of cranial nerves, their functional division into three groups. Organ of vision. Coats of the eyeball and refractile environment. The Brain. 3 primary divisions: Forebrain cortex (folded stuff) limbic system, etc (stuff around brain stem) Midbrain (top of brainstem)

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The Brain

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  1. I-XII pairs of cranial nerves, their functional division into three groups. Organ of vision. Coats of the eyeball and refractile environment.

  2. The Brain • 3 primary divisions: • Forebrain • cortex (folded stuff) • limbic system, etc (stuff around brain stem) • Midbrain (top of brainstem) • Hindbrain (bottom of brainstem + cerebellum) Organ of vision. Coats of the eyeball and  refractile environment.

  3. Hindbrain Medulla Pons Cerebellum Pons Medulla Cerebellum http://www-unix.oit.umass.edu/~psyc335c/lectures/hindbrain.gif

  4. Medulla: Controls vital reflexes: breathing, heart rate, vomiting, salivation, coughing, sneezing - Via cranial nerves Damage to medulla can be fatal Large doses of opiates can be fatal b/c suppress activity of medulla…why…?...b/c receptors there!

  5. Pons: Also has cranial nerves Location of axon decussation (where axons cross from one side of the brain to the other…so left brain controls right body and vice versa) Reticular formation: motor control, arousal, consciousness

  6. Midbrain: Cerebral aqueduct More cranial nerves Superior colliculus (visual info) Inferior colliculus (auditory info) Substantia nigra: dopamine-producing cells, structure that is lost in Parkinson’s Disease http://en.wikipedia.org/wiki/Midbrain

  7. Brainstem Medulla Pons Midbrain Some forebrain structures

  8. Senses: Information comes in the cranial nerves and eventually ends up in the cortex

  9. Cranial Nerves Table 4.4, page 87 Olfactory nerve: Smell http://www.besthealth.com/besthealth/bodyguide/reftext/images/cranial_nerves.jpg

  10. Cranial Nerves Table 4.4, page 87 Optic nerve: Vision http://www.besthealth.com/besthealth/bodyguide/reftext/images/cranial_nerves.jpg

  11. Cranial Nerves Table 4.4, page 87 Occulomotor nerve: Eye movement, pupil constriction http://www.besthealth.com/besthealth/bodyguide/reftext/images/cranial_nerves.jpg

  12. Cranial Nerves Table 4.4, page 87 Trochlear nerve: Eye movement http://www.besthealth.com/besthealth/bodyguide/reftext/images/cranial_nerves.jpg

  13. Cranial Nerves Table 4.4, page 87 Trigeminal nerve: Skin senses from face Jaw muscles for chewing and swallowing (muscles of mastication) http://www.besthealth.com/besthealth/bodyguide/reftext/images/cranial_nerves.jpg

  14. Cranial Nerves Table 4.4, page 87 Abducens nerve: Eye movements http://www.besthealth.com/besthealth/bodyguide/reftext/images/cranial_nerves.jpg

  15. Cranial Nerves Table 4.4, page 87 Facial nerve: Taste Facial expressions Crying Salivation Dilation of head’s blood vessels http://www.besthealth.com/besthealth/bodyguide/reftext/images/cranial_nerves.jpg

  16. Cranial Nerves Table 4.4, page 87 Acoustic nerve: Aka vestibulocochlear or statoacoustic Hearing Equilibrium http://www.besthealth.com/besthealth/bodyguide/reftext/images/cranial_nerves.jpg

  17. Cranial Nerves Table 4.4, page 87 Glossopharyngeal nerve: Taste Swallowing Salivation Throat movements during speech http://www.besthealth.com/besthealth/bodyguide/reftext/images/cranial_nerves.jpg

  18. Cranial Nerves Table 4.4, page 87 Vagus nerve: Sensation from neck and thorax Control of throat, esophagus, larynx Parasympathetic nerves to stomach, intestines, etc http://www.besthealth.com/besthealth/bodyguide/reftext/images/cranial_nerves.jpg

  19. Cranial Nerves Table 4.4, page 87 Spinal accessory nerve: Aka Accessory nerve Neck and shoulder movements http://www.besthealth.com/besthealth/bodyguide/reftext/images/cranial_nerves.jpg

  20. Cranial Nerves Table 4.4, page 87 Hypoglossal nerve: Muscles of tongue http://www.besthealth.com/besthealth/bodyguide/reftext/images/cranial_nerves.jpg

  21. Forebrain • Thalamus • Hypothalamus • Pituitary gland • Basal ganglia • Basal forebrain • Hippocampus • Limbic system

  22. Thalamus: Relay station for all sensory info on its way to brain (except olfactory info) Many specialized nuclei (ex: LGN, MGN…don’t have to know these!)

  23. Hypothalamus Communicates with pituitary gland to alter hormone release Involved in feeding, drinking, temperature regulation, sexual behavior, fighting, arousal (activity level)…4 Fs

  24. Pituitary gland Endocrine gland (hormone producing) Attached to base of hypothalamus by stalk Makes and releases hormones into bloodstream

  25. Basal Ganglia Motor control, but also memory and emotional expression Lose dopamine neurons in SN  Parkinson’s Disease Lose dopamine neurons in caudate & putamen  Huntington’s chorea http://www.uni.edu/walsh/basalganglia-2.jpg Don’t memorize image!!! Just understand that this is a very complex system! thalamus.wustl.edu/ course/cbell6.gif

  26. Basal forebrain Anterior and dorsal to hypothalamus Important for arousal, wakefulness, attention Lose cells in nucleus basalis  decreased attention & intellect (AD, PD) http://memorylossonline.com/summer2003/glossary/basalforebrain.jpg

  27. Hippocampus Memory formation HM: temporal lobes removed for intractable epilepsy  no longer formed new memories http://www.hermes-press.com/Perennial_Tradition/hippocampus.gif http://www.umassmed.edu/bnri/graphics/crusiofig1.gif

  28. Limbic System important for motivated & emotional behaviors (eating, drinking, sexual activity, aggressive behavior)

  29. Ventricles Contain cerebrospinal fluid (CSF) CSF reabsorbed into blood vessels, so continuous turnover Protective Reservoir for hormones, nutrients http://mywebpages.comcast.net/epollak/PSY255_pix/ventricles.PNG

  30. Ventricle size can indicate problems • Enlarged ventricles as in Alzheimer’s patients (cell loss). • Lack of ventricles due to tumors etc.

  31. Cortex • 2 hemispheres • Communicate via corpus callosum & anterior commisure • 4 lobes http://pegasus.cc.ucf.edu/~Brainmd1/brmodelc.gif http://www.urmc.rochester.edu/neuroslides/slides/slide201.jpg http://trc.ucdavis.edu/mjguinan/apc100/modules/Nervous/grosscns/images/brain10.jpg

  32. 6 laminae (layers of cells)

  33. The lobes of the cortex • Frontal • Thinking • Prefrontal cortex • Planning • Working memory • Socially appropriate behavior • Delayed-response task • Lobotomies • Primary motor cortex • Broca’s aphasia

  34. The lobes of the cortex • Parietal • Sensing • Primary sensory cortex

  35. Homunculus

  36. The lobes of the cortex • Temporal • Spoken language comprehension • Wernike’s aphasia • Hearing • Vision • Movement perception • Face recognition • Emotional motivational behavior

  37. The lobes of the cortex • Occipital • Vision • Primary visual cortex • Damage causes “cortical blindness”

  38. Functions • Forebrain • the cool stuff (thinking, perceiving, big part of emotion) • Midbrain • sensory pathways • Hindbrain • motor control, reflexes (breathing, heart rate, etc)

  39. Sensory Organs

  40. Sensory Function and Vision…

  41. The General Senses… • Sensory receptors • specialized cells that monitor the environment and relay information to the CNS. • Free nerve endings are the simplest type: they are the dendrites of sensory neurons • Complex receptors (eyes) are housed in organs • Some receptors respond to only one kind of stimulus

  42. All sensory receptors send info to the CNS via an action potential… • At the CNS, info is routed according to the stimulus and its location • The stronger the stimulus, the higher the frequency of action potentials • Some receptors adapt, that is their sensitivity to a stimulus is reduced if the stimulus is continually applied (smell) • The RAS can heighten or reduce awareness of sensory information

  43. General versus special senses… General sense receptors included those for temperature, pain, pressure, touch, vibration & proprioception (body position) These receptors are very simple in nature

  44. “Special” senses Special senses monitor vision, hearing, olfaction, gustation, and equilibrium through specialized sense organs These sense organs are highly specialized

  45. Tactile receptors… • May be simple or complex, superficial or deep, fine (provide detailed information) or crude (provide little information) • Merkel’s – fine touch and pressure • Pacinian – deep pressure • Meissner’s – fine touch and pressure in select areas • Ruffini – pressure or distortion in deep dermal layers

  46. The olfactory organs…

  47. Gustation….taste • http://www.bbc.co.uk/science/humanbody/body/factfiles/taste/taste_ani_f5.swf • Taste buds are organs containing gustatory & supporting cells that lie within papillae • Chemicals contact taste hairs which change the MP of taste cells & leads to an AP in the sensory neuron • 4 primary taste sensations – sweet, salt, sour, bitter • Sensory Pathway: sensory receptors>medulla> thalamus>primary sensory cortex

  48. A complex sensory organ: the eye. • is surrounded by accessory structures that act to protect, lubricate, and support it • is a light, compact, durable, and highly specialized hollow organ that weighs about 8 oz and measures 1 inch in diameter. • is divided into anterior (aqueous) & posterior (vitreous) cavities. • its walls are made of 3 “tunics”

  49. Accessory structures of the eye… eyelids (palpebrae) eyelashes & brows exocrine glands lacrimal apparatus Conjunctiva 6 extrinsic occulomotor muscles: the inferior, superior, lateral and medial rectus muscles the superior and inferior oblique muscles

  50. Eye anatomy….. • http://www.macula.org/anatomy/eyeframe.html • The hollow eye is divided into 2 cavities: • An anterior cavity which contains aqueous humor • A posterior cavity which holds vitreous humor • Humors act to stabilize eye shape and provide nutrients

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