Summer BI232 Brain HW 2023

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Portland Community College *

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Biology

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Feb 20, 2024

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Bi 232 Chapter 14 Brain Homework Please read the syllabus and then study the Brain slides and chapter 14 in your text. You may submit your answers in the D2L Assignment Box or in person. If you do your homework online, it is really helpful if you differentiate your writing from the questions: using a color for your text, or bold print, italics, a different font, highlighting - anything to make the questions and answers look different from each other. Thank you. 1. Write and spell correctly the full name of your instructor below. Karen Toyooka 2. Did you read the syllabus in its entirety? If not, please do so as soon as possible. yes 3. What are the consequences for cheating in this course? result in disciplinary actions including but not limited to receiving a failing grade 4. Will I lecture about everything for which you will be tested? Rather than teaching every single fact, you show us directions. 5. When is the last possible drop date for this course this term? July 4, 2023. 6. Looking at the image on slide 3, what general trend do you notice with regards to the degree of folding of the brain neural tissue between the various organisms depicted? What effect (think in terms of a physical property) does the degree of folding have brain processing power, and why? As degree of folding increases, intelligence as well increases. As folding rises, physical properties such as mass also increase. 7. Define the terms rostral and caudal (slide 5) - also from BI 231! Rostral therefore refers to the anterior (front) aspect of the head. Caudal refers to the posterior (back) of the head.

8. Name the three main regions of the brain visible on gross inspection. (slides 5, 6). Your instructor will discuss 6 regions of the adult brain. Brainstem, cerebrum, and cerebellum 9. Describe the following characteristics of the cerebrum: a. Gyrus (plural gyri) – fold on the cerebrum. b. Sulcus (plural sulci) – grooves between the gyrus. c. Hemispheres – the left and right sides of the brain. d. Longitudinal fissure (a space, not technically part of the cerebrum) – a deep groove separating the two hemispheres. 10. Describe these characteristics of the cerebellum: e. Folia – small leaflike laminae of cerebellum. f. Sulcus – a depression or groove. 11. List the three structures of the brainstem. Make sure you can arrange them caudally to rostrally (or vice versa) and be able to label or point them out on a diagram. Mid brain Pons Medulla oblongata 12. Define white matter and describe what parts of neurons, and what specific cellular material, makes up white matter. (slide 7) White matter which is found in the deeper tissues of the brain is made up of nerve fibers that are extensions of nerve cells. 13. Describe where most gray and white matter is found in the cerebrum and cerebellum. In the cerebrum and cerebellum gray is primarily superficial; white matter is found else where.

14. List four ways the delicate brain tissue is protected (slide 8). Meninges which is comprised of three main layers, the strong cranial bones, CSF in the cranial cavity , and brain barrier system all together protect the brain. 15. Name the three primary meninges of the cranial cavity. Which of these meninges has two specific layers? (slide 8) Dura mater has two layers ( perosteal and meningial) Arachnoid mater Pia mater 16. Describe the location of these structures formed by the meningeal layer of the cranial dura mater (consult your text): g. Falx cerebri – invagination into the longitudinal fissure between the cerebral hemispheres. h. Tentorium cerebelli – found at posterior cranial fossa. i. Falx cerebelli – found at occipital bone. 17. Name the three primary dural sinuses formed where the two layers of the cranial dura mater separate. What is found in these sinuses (slide 9)? Superior sagittal sinus, transverse sinus and inferior sagittal sinus. Sinus ontains venous blood.

18. List the four ventricles of the central cavity of the brain. [Be able to describe their spatial arrangement from rostral to caudal - you may want to practice that]. List the names of the tubes that connect the various ventricles (slide 11). 2 lateral ventricles (1 in each cerebral hemisphere), the third ventricle in the diencephalon, and the fourth ventricle in the hindbrain. The tubes are interventricular foramina and cerebral aqueduct. 19. What is the ‘average’ number of milliliters of CSF that are in circulation? How is the composition of CSF different from blood plasma? (slide 12) It is 100 – 160 ml. compared to plasma it has more sodium and chloride, Less potassium, calcium, and protein. 20. List five functions of CSF.  Increases brain buoyancy  Absorbs shock  Transports gases, wastes, and nutrients  Maintains appropriate environment for action potentials  Helps brain to thermo regulate 21. What structure, found in each ventricle, is responsible for creating cerebral spinal fluid (CSF) there? What is this structure composed of (types of cells, tissues)? (slide 13) choroid plexus which is network of blood vessels. 22. Describe, step by step, the process of CSF circulation. (slide 13/14) Be sure to properly name any structure which CSF passes through.

CSF flows through inter ventricular foramina to 3 rd ventricle then choroid plexus in 3 rd ventricle adds more csf. The CSF flows to the 4 th ventricle through cerebral aqueduct followed by flowing to lateral ventricle. finally, it fills the subarachnoid space where it is reabsorbed into venous blood. 23. Name the major blood vessels (arteries and veins) delivering oxygenated blood to the brain and draining the brain of deoxygenated blood. (slide 16) Internal carotid artery and internal jugular vein. 24. Describe the protective function of the cerebral arterial circle (of Willis). It allows for alternate routes of flow in case there is a blockage. 25. What types of substances pass easily across the blood-brain barrier (BBB) (slide 17)? Glucose, water, O 2 , CO 2 , alcohol, nicotine, caffeine, and anesthetics cross easily. 26. What cells and cellular structures make up the blood-brain barrier? What cells and cellular structures make up the blood-CSF barrier? (slide 17/18). What types of substances cannot cross these barriers easily?. BBB is made of astrocytes; blood CSF barrier is made of ependymal cells. Bacteria, viruses, antibiotics, and cancer drugs have a hard time crossing. 27. What are the circumventricular organs (CVOs), and what functions do they serve (slide 19)? [Your instructor will refer to them as “leaky spots”]. Memorize the two in bold print. They are small collections of tissue surrounding third and fourth ventricles. They increase permeability of BBB and have homeostatic function as well. 28. Describe the location of the diencephalon with relation to the brainstem (image on slide 20). It is found superior to the brainstem. 29. How many pairs of cranial nerves are there, and how many of them arise from the brainstem? Contains 10 of the 12 pairs of nuclei for of cranial nerves.

30. Name the tracts located in the pyramids of the medulla oblongata. Describe the type of information that travels through these pyramidal tracts. (slide 21) Corticospinal tracts – which carries motor signals from the primary motor cortex in the brain, down the spinal cord. 31. Define the decussation of the pyramids. It is the crossing of the fibers of the corticospinal tracts. 32. Describe where the gracile and cuneate fasciculi are in the medulla and list their specific functions. Do fibers traveling through these structures decussate, and if so, where do they do this? (slide 22) Appear as two pairs of ridges on the medulla; gracille medially and cuneate laterally. First order neurons decussate in this fascicule. gracile fasciculus carries sensory input from vertebral level T6 and below; The cuneate fasciculus carries information from T6 and above. 33. How would a stroke on the left side of the brain affect sensory and motor function throughout the body? It affects sensation and motor activity of the opposite side of the body. 34. In general, what is the function of the medulla oblongata? What are some specific functions of this structure? (slide 23) Medulla also serves as the body’s life support system such as heart rate, blood vessel diameter, and respiratory rate via the ANS 35. What is the function of the inferior olivary nuclei? Relay stations between brain/spinal cord, and cerebellum 36. What is the function of the cochlear nuclei, and with what cranial nerve pair are they associated? (slide 24)

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