Lecture 13
Nervous System II: Brain
13-1
Brain
Major parts of the brain
–
–
–
–
Brainstem
Cerebellum
Diencephalon
Cerebrum
13-2
Brainstem
• Connects spinal cord to brain
• Parts
– Medulla oblongata
– Pons
– Mesencephalon
Fig. 15.1
13-3
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
13-4
Cerebellum
• Involved in control of:
balance, posture, locomotion,
and fine motor coordination
producing smooth flowing
movements
Fig. 15.22
13-5
Diencephalon
• Components
– Thalamus, Epithalamus, Hypothalamus
Fig. 15.15
13-6
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 sleepwake cycle
13-7
Cerebrum
• Largest portion of brain
• Hemispheres
– Right
– Left
– Lobes: frontal, parietal,
occipital, temporal, insula
• Gyrus
• Sulcus
Fig. 15.10
Fig. 15.1
13-8
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
13-9
Ventricles
Fig. 15.6
• Ventricles: Lateral ventricles (2), third ventricle,
fourth ventricle
• Choroid plexuses produce CSF which fills
ventricles and other parts of brain and spinal cord
13-10
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
13-11
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)
13-12
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
13-13
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.
13-14
Questions?
13-15