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Nervous System II: BrainLecture 13

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Brain

Major parts of the brain– Brainstem

– Cerebellum

– Diencephalon

– Cerebrum

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Brainstem

• Connects spinal cord to brain• Parts

– Medulla oblongata– Pons– Mesencephalon

Fig. 15.1

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Brainstem• Medulla oblongata or medulla

– Regulates: Heart rate, blood vessel diameter, respiration, swallowing, vomiting, hiccupping, coughing, and sneezing

• Pons– Sleep and respiratory center

• Mesencephalon– Integral part of auditory

pathways in CNS

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Cerebellum• Involved in control of:

balance, posture, locomotion, and fine motor coordination producing smooth flowing movements

Fig. 15.22

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Diencephalon

• Components– Thalamus, Epithalamus, Hypothalamus

Fig. 15.15

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Diencephalon

• Thalamus– Largest part of

diencephalon

– Most sensory input projects to here

– Influences mood and actions as fear or rage

• Epithalamus– Pineal gland may

influence sleep-wake cycle

• Hypothalamus– Functions

• ANS control

• Endocrine control

• Muscle control

• Temperature regulation

• Regulation of food and water intake

• Emotions

• Regulation of sleep-wake cycle

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Cerebrum• Largest portion of brain• Hemispheres

– Right – Left– Lobes: frontal, parietal,

occipital, temporal, insula

• Gyrus• Sulcus

Fig. 15.10

Fig. 15.1

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Meninges• Connective tissue

membranes– Dura mater:

Superficial– Arachnoid mater– Pia mater:

Bound tightly to brain

– Spaces • Subdural:

Serous fluid• Subarachnoid:

Cerebrospinal fluid (CSF)

Fig. 15.4

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Ventricles

• Ventricles: Lateral ventricles (2), third ventricle, fourth ventricle

• Choroid plexuses produce CSF which fills ventricles and other parts of brain and spinal cord

Fig. 15.6

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Cerebrospinal Fluid (CSF)

• Similar to serum with most of proteins removed

• Bathes brain and spinal cord• Provides a protective cushion around CNS• Provides some nutrients to CNS tissues• Produced by ependymal cells in the

ventricles of the brain

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Brain Blood Supply• Brain

– Requires tremendous amount of blood– Receives 15-20% of blood pumped by heart– Interruption can cause unconsciousness and

irreversible brain damage– High metabolic rate and dependence on

constant supply of oxygen and glucose– Receives blood through arteries

• Internal carotid arteries (carotid canal) and vertebral arteries (foramen magnum)

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Review Question

The primary link between the nervous system and the endocrine system (consists of glands that secrete hormones) is the

(a) Hypothalamus

(b) Pons

(c) Medulla oblongata

(d) Cerebellum

(e) Midbrain

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Points to Remember• Major parts of brain are: brain stem, cerebellum,

diencephalon and cerebrum.• Injury to medulla oblongata often fatal since it

contains vital parts for control of breathing, heart rate and blood pressure.

• Cerebellum provides important control of skeletal muscles for coordination of movement and posture.

• Diencephalon functions in several emotions and control of sleep-wake cycle.

• Cerebrum is largest part of brain with functions in emotions, higher level thinking, interpretation of sensory data and muscular control.

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Questions?