Biomed II: Structure of Brain

Brain Stem

* regulates body automatic functions; necessary for survival
* connects spinal cord to brain
* contains pons, medulla oblongata, & midbrain

Midbrain/Mesencephalon

* visual & auditory reflexes; consciousness


* Substantia Nigra

Substantia Nigra

* motor regulation
* neuromelanin pigment (black substance)

Structural Plasticity

experiences/memories change brain’s physical structure

Functional Plasticity

brain functions move from damaged areas to healthy areas

Medulla Oblongata

* controls automatic behaviors necessary for survival (BP, HR, breathing)
* connects brain & spinal cord

Pons

* connects cerebellum to brain stem
* subconscious motor control
* regulates breathing & CO2 levels

Cerebellum

* 11% of brain’s mass
* controls balance & coordination
* Muscle Memory
* Arbor Vitae

Arbor Vitae

* treelike pattern of cerebellar white matter in center of cerebellum
* helps provide sensory information to brain

Diencephalon

* connects brainstem to cerebrum
* above diencephalon: conscious
* below diencephalon: unconscious
* contains thalamus, hypothalamus, epithalamus

Thalamus

* filters & decides what should/shouldn’t bother brain
* sensory relay center
* can’t filter smell

Hypothalamus

* maintains homeostasis; regulates hunger/thirst


* has infundibulum
* produces Antidiuretic Hormone (ADH) & Oxytocin (OXT)
* transports hormones to pituitary gland
* regulates production of melatonin (pineal gland)

Indundibulum

connection to pituitary gland

Epithalamus

* location of pineal gland
* no neurons, only glial cells & pinealocytes

PIneal Gland

* secretes melatonin
* regulates circadian rhythm
* called seat of soul (Descart)

Pinealocytes

releases melatonin, astrocytes, microglia, endothelial cells

Cerebrum

* 83% of brain’s mass
* conscious motor activity
* 2 cerebral hemispheres connected by corpus callosum
* 5 lobes of each hemisphere

Corpus Callosum

* thick bundle of nerve fibers that connect 2 cerebral hemispheres
* communicates & sends signals to hemispheres

Central Sulcus

separates frontal & parietal lobe

Frontal Lobe

motor functions, complex thinking, intelligence (lobe)

Parietal Lobe

primary sensory cortex; touch temperature (lobe)

Lateral Sulcus

separates frontal lobe from temporal

Occipital Lobe

visual cortex (lobe)

Temporal Lobe

auditory & olfactory (smell) cortex, memory retrieval (lobe)

Insula

gustatory (taste) cortex

Hemisphere Lateralization

certain functions exist on 1 half of brain but not other

Left Hemisphere

controls language, math, logic, & reading/writing

Right Hemisphere

controls sensations, tough, taste, voice, face recognition, & artistic skills

Meninges

* 3 CT membranes that are external to CNS & cover/protect CNS inside skull
* includes dura, arachnoid, & pia mater

Dura Mater

strong outer layer meninge

Arachnoid Mater

* middle layer meninge that forms loose brain covering
* Arachnoid Villi allows CSF to be absorbed

Pia Mater

* deepest meninge layer
* delicate CT that clings to brain & carries blood vessels

Ventricles

* network of cavities inside brain
* filled w/ CSF & lined by ependymal cells
* produce, monitor, transport, & remove CSF
* cushions & supports brain; transports nutrients

Cerebrospinal Fluid (CSF)

* produced by ependymal cells & replaced 3 times a day (500 mL/day)
* prevents brain from being crushed
* protects CNS from trauma & nourishes brain
* carries chemical signals

Choroid Plexus

* network of capillaries & ependymal cells
* maintaining blood CSF barrier

CSF Analysis Diagnosis

* meningitis: infection; lactic acid elevation
* intracranial bleeding
* tumors in brain/spine
* multiple sclerosis: demyelination (ex: cytokines)