1. 2 chapter 11 the nervous system the brain, cranial nerves, autonomic nervous system, and the...

1

2

Chapter 11The Nervous System

The Brain, Cranial Nerves, Autonomic Nervous System,

and the Special Senses

3

Introduction

• Brain is divided into four main parts– Brainstem: controls breathing, heartbeat rates

and reactions to auditory and visual stimuli– Diencephalon: controls homeostasis– Cerebrum: controls intellectual processes and

emotions– Cerebellum: maintains body posture and

balance

4

The Principal Parts of the Brain

5

The Principal Parts of the Brain (cont’d.)

• Main parts: brainstem, diencephalon, cerebrum, and cerebellum

• Protection– Cranial bones– Meninges– Cerebrospinal fluid

• Ventricles– Interventricular foramen

6

The Principal Parts of the Brain (cont’d.)

7

The Anatomy and Functions of the Brainstem

8

The Anatomy and Functions of the Brainstem (cont’d.)

• Medulla oblongata– Ascending and descending tracts– Connect spinal cord with the brain– Some tracts cross over in medulla– Reticular formation: controls consciousness– Reflex centers

9

• Pons varolii– Connects spinal cord with brain– Connects parts of brain with each other– Helps control breathing

The Anatomy and Functions of the Brainstem (cont’d.)

10

The Anatomy and Functions of the Brainstem (cont’d.)

• Midbrain– Ventral cerebral peduncles: convey impulses

from cortex to pons and spinal cord– Dorsal tectum: reflex center– Controls movement of head and eyeball

(visual stimuli)– Controls movement of head and trunk

(auditory stimuli)

11

The Anatomy and Functions of the Diencephalon

12

The Anatomy and Functions of the Diencephalon (cont’d.)

• Optic tracts

• Mamillary bodies: memory and emotional responses

• Thalamus– Relay station for sensory impulses– Interpretation center for pain, temperature,

and touch

• Epithalamus: contains pineal gland

13

The Anatomy and Functions of the Diencephalon (cont’d.)

• Hypothalamus: homeostasis– Controls and integrates autonomic nervous

system– Receives sensory impulses from internal

organs– Controls pituitary gland and links endocrine

and nervous systems

14

The Cerebrum: Structure and Function

15

The Cerebrum: Structure and Function (cont’d.)

16

The Cerebrum: Structure and Function (cont’d.)

• Cerebral cortex: gray matter surface

• Longitudinal fissure separates two hemispheres

• Gyri: folds

• Sulci: grooves

• Corpus callosum: bridge connecting two hemispheres

17

The Cerebrum: Structure and Function (cont’d.)

• Surface of the cortex– Motor areas control muscular movements– Sensory areas interpret sensory impulses– Association areas process emotions and

intellect

18

The Cerebrum: Structure and Function (cont’d.)

• Cerebral hemispheres– Frontal lobe: muscle movement, moods,

aggression, smell, motivation– Parietal lobe: touch, pain, balance, taste,

temperature– Temporal lobe: hearing, smell, memory,

abstract thought, judgment– Occipital lobe: vision

19

The Cerebrum: Structure and Function (cont’d.)

20

The Cerebellum: Structure and Function

21

The Cerebellum: Structure and Function (cont’d.)

• Butterfly-shaped

• Two partially separated hemispheres connected by vermis

• Functions– Coordinating muscular movements– Maintaining posture– Maintaining balance

22

The Autonomic Nervous System

23

The Autonomic Nervous System (cont’d.)

• Subdivision of efferent PNS

• Functions without conscious effort

• Regulates functions of internal organs

• Assists in maintaining homeostasis

• Helps deal with emergency situations

24

The Autonomic Nervous System (cont’d.)

• Sympathetic– Energy and stressful situations– Increases heartbeat and breathing rates– Neurotransmitters: acetylcholine and

norepinephrine

25

The Autonomic Nervous System (cont’d.)

• Parasympathetic– Restores body to nonstressful state– Neurotransmitter: acetylcholine– Stimulates digestion, urination, and defecation

26

The 12 Cranial Nerves and Their Functions

27

The 12 Cranial Nerves and Their Functions (cont’d.)

• (I) Olfactory: smell

• (II) Optic: sight

• (III) Oculomotor: movement of eyeball, constriction of pupil

• (IV) Trochlear: movement of eyeball

28

The 12 Cranial Nerves and Their Functions (cont’d.)

• (V) Trigeminal: chewing, sensations in teeth

• (VI) Abducens: movement of eyeball

• (VII) Facial: facial expression, taste, tear and salivary glands

• (VIII) Vestibulocochlear: equilibrium, hearing

29

The 12 Cranial Nerves and Their Functions (cont’d.)

• (IX) Glossopharyngeal: swallowing, taste, salivary glands

• (X) Vagus: certain muscle movements, sensory impulses

• (XI) Accessory: swallowing, head movement

• (XII) Hypoglossal: swallowing, speech

30

The Special Senses

31

The Sense of Smell

• Molecules in air dissolve in nasal mucus

• Bipolar sensory neurons transfer chemical impulse

• Olfactory bulbs receive impulse

• Impulse sent to olfactory cortex

• Odor variety dependent on brain interpretation

32

The Sense of Smell

33

The Sense of Taste

• Taste buds on tongue, palate, and pharynx

• Taste bud cell types– Exterior capsule: epithelial cells– Interior: taste cells

• Taste depends on chemicals dissolved in saliva

• Taste influenced by olfactory sensations

34

The Sense of Taste

35

The Sense of Sight

• Eyes protected by eyelids and eyelashes

• Tears– Lubricate the eyes– Contain bacteriolytic lysozyme enzyme– Contain salt and gamma globulin

36

The Sense of Sight (cont’d.)

37

The Sense of Sight (cont’d.)

38

The Sense of Hearing and Equilibrium

• Outer ear– Auricle: external, visible, flexible part– External auditory meatus

• Lined with hair and ceruminous glands

– Tympanic membrane: vibrates in response to sound

39

The Sense of Hearing and Equilibrium

40

The Sense of Hearing and Equilibrium

41

The Sense of Hearing and Equilibrium (cont’d.)

• Middle ear– Auditory ossicles: malleus, incus, and stapes– Openings: oval and round windows– Eustachian tube: equalizes pressure

42

The Sense of Hearing and Equilibrium (cont’d.)

• Inner ear– Cochlea: hearing – Equilibrium

• Static: vestibule• Kinetic: semicircular canals

43

Summary

• Named the principal parts of the brain

• Discussed the functions of the major parts of the brain

• Named the 12 cranial nerves

• Discussed the role of the autonomic nervous system and its divisions

• Described the special senses and the organs involved