A&P Chapter 14 - Principles of Human Anatomy and...

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Unformatted text preview: Principles of Human Anatomy and Physiology, 11e 1 Zool 2013 Chapter 14 Part 1 The Brain and Cranial Nerves Lecture Outline Dr. Navin Maswood 2 INTRODUCTION • Largest organ in the body at almost 3 lb. • Brain functions in sensations, memory, emotions, decision making, behavior • The brain is the center for registering sensations, correlating them with one another and with stored information, making decisions, and taking action. • It is also the center for intellect, emotions, behavior, and memory. • It also directs our behavior towards others. • In this chapter we will consider the principal parts of the brain, how the brain is protected and nourished, and how it is related to the spinal cord and to the 12 pairs of cranial nerves. 3 OVERVIEW OF BRAIN ORGANIZATION • The major parts of the brain are the brain stem , diencephalon , cerebrum , and cerebellum (Figure 14.1). • The CNS develops from an ectodermal neural tube – Three primary vesicles develop from the neural tube : A) Prosencephalon ( telencephalon & diencephalon) (Forebrain) B) Mesencephalon (mesencephalon) (Mid brain) C) Rhombencephalon (metencephalon & mylencephalon) (hindbrain) – The embryologic development of the CNS is summarized in table 14.1 4 Development of Principal Parts • By end of 4th week, 3 anterior enlargements occur – prosencephalon – mesencephalon – rhombencephalon Neural tube defects associated with low levels of folic acid (B vitamins) spina bifida is failure to close of vertebrae anencephaly is absence of skull & cerebral hemispheres 5 Principal Parts of the Adult Brain • Cerebrum- largest part of the brain • Diencephalon – thalamus & hypothalamus • Cerebellum • Brainstem – medulla, pons & midbrain 6 Blood Flow and the Blood-Brain Barrier • An interruption of blood flow for 1 or 2 minutes impairs neuronal function. – A total deprivation of oxygen for 4 minutes causes permanent injury. • Because carbohydrate storage in the brain is limited, the supply of glucose to the brain must be continuous. – Glucose deficiency may produce mental confusion, dizziness, convulsions, and unconsciousness. 7 BBB • A blood-brain barrier ( BBB ) protects brain cells from harmful substances and pathogens by serving as a selective barrier to prevent passage of many substances from the blood to the brain. • An injury to the brain due to trauma, inflammation, or toxins causes a breakdown of the BBB, permitting the passage of normally restricted substances into brain tissue. • The BBB may also prevent entry of drugs that could be used as therapy for brain cancer or other CNS disorders, so research is exploring ways to transport drugs past the BBB. 8 Protective Covering of the Brain • The brain is protected by the cranial bones and the cranial meninges (Figure 14.2)....
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This note was uploaded on 04/14/2008 for the course ZOOL 2013 taught by Professor Maswood during the Spring '08 term at Texas Woman's University.

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A&P Chapter 14 - Principles of Human Anatomy and...

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