Fisiologi Sistem Saraf Pusat

PHYSIOLOGY CENTRAL

NERVOUS SYSTEM

THE BRAIN

Major Parts of the Brain

 Cerebrum

 Cerebellum

 Diencephalon

 Brain stem

P

ROTECTION OF THE BRAIN

 Cranium

 Cranial meninges

 Dura mater

 Arachnoid mater

 Pia mater

B

^LOOD

F

^LOW

 internal carotid arteries

 vertebral arteries

 Internal jugular veins

B

LOOD–

B

RAIN

B

ARRIER

 Protects brain cells from harmful substances and pathogens

 Tight junctions (+)

 water-soluble substances : glucose, cross the BBB by active transport.

 creatinine, urea, and most ions, cross the BBB very slowly

 proteins and most antibiotic drugs—do not pass BBB

 lipid-soluble substances : oxygen, carbon dioxide,

alcohol, and most anesthetic agents, easily cross the blood–brain barrier.

 Trauma, certain toxins, and inflammation can cause a breakdown of BBB

CEREBROSPINAL FLUID

 Clear, colorless liquid

 Protects brain and spinal cord from injuries

 carries oxygen, glucose, and other needed chemicals from blood to neurons and

neuroglia

 circulates through cavities in brain and spinal cord and around the brain and spinal cord in subarachnoid space (between arachnoid

mater and pia mater).

 CSF volume : 80 to 150 mL (adult)

 contains glucose, proteins, lactic acid, urea, cations (Na, K, Ca2, Mg2), and anions (Cl and HCO3), some white blood cells

Function

 1. Mechanical protection

 shock-absorbing medium

 2. Chemical protection

 provides an optimal chemical environment for accurate neuronal signaling

 3. Circulation

 allows exchange of nutrients and waste products between blood and nervous tissue.

F

ORMATION OF

CSF

 Ventricles : CSF-filled cavities within the brain

 lateral ventricle : in each hemisphere of cerebrum.

Anteriorly separated by septum pellucidum (SEP-tum pe-LOO- sidum

 3rd ventricle : narrow cavity along midline superior to

hypothalamus and between

right and left halves of thalamus

 4th ventricle lies between brain stem & cerebellum.

F

ORMATION OF

CSF

 choroid plexuses in the walls of the ventricles

 ependymal cells that form

cerebrospinal fluid from blood plasma by filtration and secretion

C

IRCULATION OF

CSF

BRAIN STEM

 part of the brain between spinal cord and diencephalon

 3 structures :

 (1) medulla oblongata

 (2) pons

 (3) midbrain

MEDULLA OBLONGATA

 sensory (ascending) tracts

 motor (descending) tracts

 Pyramids :

corticospinal tracts

 Decussation of pyramids

N UCLEI (COLLECTION OF NEURONAL CELL BODIES WITHIN THE CNS ⁾

 Cardiovascular center

 medullary rhythmicity area :respiratory center

 vomiting & Deglutition center

 Inferior olivary nucleus

 Gracile nucleus & cuneate nucleus

 gustatory nucleus

 cochlear nuclei

 vestibular nuclei

 Nuclei of 5 pairs of cranial nerves vestibulocochlear (VIII), glossopharyngeal (IX) nerves,

vagus (X) , accessory (XI) nerves (cranial portion) hypoglossal (XII) nerves.

P

ONS

 Bridge that connects different parts of the brain with one another

 pontine nuclei : relayed signals for voluntary

movements from motor areas of cerebral cortex

 vestibular nuclei : components of equilibrium pathway from inner ear to the brain

 pneumotaxic area & apneustic area : respiration

 Nuclei of 4 pairs of cranial nerves : trigeminal (V) nerves, abducens (VI) nerves, facial (VII) nerves, and vestibulocochlear (VIII) nerves.

M

IDBRAIN

 contains nuclei and tracts

 Cerebral peduncles : axons of corticospinal, corticopontine, and corticobulbar tracts (conduct nerve impulses from motor areas in cerebral cortex to spinal cord, pons, and medulla)

 Tectum

 superior colliculi (reflex centers for certain visual activities)

 inferior colliculi (relaying impulses from the receptors for hearing in the inner ear to the brain)

 substantia nigra

 red nuclei

 look reddish (rich blood supply and an iron- containing pigment in neuronal cell bodies)

 help control some voluntary movements of the limbs

 Nuclei of 2 pairs of cranial nerves:

 oculomotor (III) nerves and trochlear (IV) nerve

R

ETICULAR

F

ORMATION

 broad region where white matter and gray matter exhibit a netlike arrangement

 ascending (sensory) functions

 Reticular activating system (RAS)

 sensory axons project to cerebral cortex

 helps maintain consciousness and is active during awakening from sleep

 descending (motor) functions

 help regulate posture and muscle tone

THE CEREBELLUM

• Smoothes and coordinates

contractions of skeletal muscles

• Regulates posture and Balance

• May have a role in cognition and language

processing

 central constricted area : vermis ( worm)

 Cerebellar hemispheres

 Anterior and posterior lobe govern subconscious aspects of skeletal muscle movements

 flocculonodular lobe : equilibrium and balance

 Cerebellar cortex

 consists of gray matter/ folia ( leaves)

 cerebellar nuclei

 axons carrying impulses from the cerebellum to other brain centers

 cerebellar peduncles

 Superior, middle, and inferior

 Conduct impulses between the cerebellum and other parts of the brain.

C

EREBRUM (

C

EREBRAL

H

EMISPHERES)

 Cerebral cortex is gray matter over white matter

 2-4 mm thick contains billions of cells

– Folds (gyri) & grooves (sulci or fissures)

 Longitudinal fissure: separates L & R Cerebral Hemispheres

 Corpus callosum band of white matter connects L & R cerebral hemis.

 Each hemisphere is subdivided into 4 lobes :

 Frontal

 Parietal

 Temporal

 Occipital

F

UNCTIONAL ORGANIZATION OF THE CEREBRAL CORTEX

 Sensory area

 Primary somatosensory area (areas 1,2, and 3)

 Primary visual area (area 17)

 Primary auditory area (areas 41 and 42)

 Primary gustatory area (area 43)

 Primary olfactory area (area 28)

 Motor area

 Primary motor area (area 4)

 Broca’s speech area (areas 44 and 45)

 Association area

C

EREBRAL

W

HITE

M

ATTER

 Association tracts

 axons that conduct nerve impulses between gyri in the same hemisphere

 Commissural tracts

 axons that conduct nerve impulses from gyri in one cerebral hemisphere to corresponding gyri in the other cerebral hemisphere.

 corpus callosum , anterior commissure, and posterior commissure.

 Projection tracts

 axons that conduct nerve impulses from the cerebrum to lower parts of the CNS (thalamus, brain stem, or spinal cord) or from lower parts of the CNS to the cerebrum

DIENCEPHALON



Thalamus



Hypothalamus



Epithalamus

11/11/2024

32

GANGLIA BASALIS

GANGLIA BASALIS

 help initiate and terminate movements of the body

 Suppress unwanted movements and regulate muscle tone

 influence many aspects of cortical function, including sensory, limbic, cognitive, and

linguistic functions

 Disorders : Parkinson disease

L

IMBIC

S

YSTEM

• Sistem limbik: jaringan otak di sekitar hilus

hemispherium cerebri (hippocampus, amygdala, lobus limbik, thalamus, mesencephalon, septal nuclei)

• Korteks limbik  bagian tertua cortex, dari allocortex & juxtallo cortex

 “emotional brain”

 primary role in a range of emotions

 pleasure, pain, docility, affection, fear, and anger

 olfaction (smell) and memory

 hippocampus, together with other parts of the cerebrum, functions in memory

• Koneksi sistem limbik (sirkuit tertutup):

Hippocampus – Fornix – Corpus mamillaris – Nuclei thalamus anterior – Cortex cingulatum – Hippocampus

11 Nov 2024

38

Terima kasih...