Lecture 13 Nervous System II Brain 1 Brain

Lecture 13 Nervous System II: Brain 1

Brain Major parts of the brain – – Brainstem Cerebellum Diencephalon Cerebrum 2

Brainstem • Connects spinal cord to brain • Parts – Medulla oblongata – Pons – Mesencephalon Fig. 15. 1 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 4

Cerebellum • Involved in control of: balance, posture, locomotion, and fine motor coordination producing smooth flowing movements Fig. 15. 22 5

Diencephalon • Components – Thalamus, Epithalamus, Hypothalamus Fig. 15 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 7

Cerebrum • Largest portion of brain • Hemispheres – Right – Left – Lobes: frontal, parietal, occipital, temporal, insula • Gyrus • Sulcus Fig. 15. 10 Fig. 15. 1 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 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 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 11

Brain Blood Supply • Brain – Requires tremendous amount of blood – Receives 15 -20% of blood pumped by heart – Interruption 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) 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

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. 14

Questions? 15