1. UNIT 5: Nervous System – part 4 THE HUMAN BRAIN (vital part of CNS)

2. Protective Structures
The brain and spinal cord are delicate and vital organs and are protected by two coverings
1. Outer bone coverings
2. Inner membranes called the “meninges”

3. Meninges Consists of 3 layers Dura mater – “Tough Mother”
Outer layer
Made of a thick fibrous tissue
Also has extensions which separate parts of the brain
Arachnoid mater
Middle layer
Delicate, cobweb like-layer
Pia mater
Innermost layer
Transparent and adheres to blood vessels on the outer surface of the brain and spinal cord

5. An infection or inflammation of the meninges is called meningitis
Usually caused by virus but could also be bacterial or even fungus (bacterial can come on swiftly!)
Brain swelling leads to symptoms: include sudden high fever, severe unrelenting headache, neck stiffness, vomiting, confusion
Meningitis may range from a mild condition to a fatal illness

6. Protective Structures (cont.)
Between the bone & the meninges: additional protection from cerebrospinal fluid
Cushions & nourishes the brain & spinal cord

7. Fun Brain Facts!
The brain is one of the largest organs in the adult human body
It weighs about 3 lbs.
Also contains about 100 billion neurons and 900 billion glial cells 
The brain grow rapidly through the first 9 years, attains full size by the 18th year

8. Parts of the Brain: The brain has 4 main regions: CEREBRUM CEREBELLUM
BRAIN STEM
DIENCEPHALON

9. 1) CEREBRUM:  Divided into hemispheres (R and L)
 Each hemisphere divided into lobes (frontal, parietal, temporal, occipital)
Each hemisphere has a highly folded outer covering of gray matter = CEREBRAL CORTEX
Hemispheres are connected by white
matter called CORPUS CALLOSUM
Roughly over 200 million axons!

13. CEREBRUM – functions! Where memories are stored
Interprets sensory impulses arriving from sense organs
 Centers for motor coordination; send motor impulses to muscles
Where conscious decisions are made
Intelligence and personality stem from cerebral activity

14.  3 functional cortical areas:
1) Motor Cortex: sends commands to skeletal muscles

15. 2) Somatosensory Cortex:
*Receives and integrates signals from touch, pain, pressure, and temperature receptors;
*Divided into specific areas so that we can associate specific stimuli with specific parts of the body. 

18. Analyze & interpret sensory experiences
3) Association Areas:
Areas of the cerebral cortex that are outside the primary sensory areas
Essential for more complex mental functions
Analyze & interpret sensory experiences
Oversee memory, reasoning, verbalizing, judgment, & emotion
Ex: association areas of the frontal lobe control many higher intellectual processes vs. assoc. areas in occipital lobes deal with visual interpretation

20. Language
Language functions consist of the ability to speak and write words, and the ability to understand spoken and written words.
Wernicke’s area is located posteriorly in the temporal lobe
This area is responsible for understanding written and spoken language
Broca’s area is a large speech center located in the frontal lobe
Damage to Broca’s area would cause a person to be unable to articulate words, but still make vocal sounds and understand written and spoken language

22. Specialization of Cerebral Hemispheres
The right and left hemispheres of the cerebrum
specialize in different functions
The left hemisphere: language functions, and
dominates hand movements (especially skilled
gestures and movements)
Most of the population uses their right hands
The right hemisphere: perception of certain auditory stimuli, tactual perception, and in perceiving and visualizing spatial relationships
Despite specializations in each hemisphere, both hemispheres communicate with each other through the corpus collosum

24. 2) CEREBELLUM:
coordination of movement;
balance;
hand-eye coordination

25. superior end of spinal cord; 3 parts that function in:
3) BRAINSTEM:
superior end of spinal cord;
3 parts that function in:
-Homeostasis, Movement coordination, Conduction of info. to higher brain centers:
Medulla oblongata
Pons
Midbrain

26. 1) Medulla oblongata: controls involuntary reflexes like breathing, heart and blood vessel activity, swallowing, vomiting, sneezing, digestion

27. 2) Pons: regulates breathing centers in the medulla oblongata

28. 3) Midbrain: receives and sends sensory information that coordinates eye movements/head movements to respond to stimuli

29. 4) DIENCEPHALON: (Between Brain):
Located between the cerebral hemispheres and above the midbrain.
Includes the:
thalamus
hypothalamus
optic tracts & optic chiasma
posterior pituitary gland
pineal gland

31. THALAMUS: relay center that sorts out & transmits sensory information to and from cerebrum

32. HYPOTHALAMUS:  Important regulator of HOMEOSTASIS
 Contains body’s thermostat (regulates temperature)
 Includes centers for regulating hunger & thirst
 Plays role in sexual response and mating behavior
 Fight-or-flight response, pleasure, daily biorhythms

34. Pineal Gland (Body)
Located below the hypothalamus and named pineal gland because its structure resembles a small pinecone
-Functions of the pineal gland are not well understood but it is thought to be involved in regulating the body’s biological clock
-Produces the hormone melatonin, which is thought to synchronize various body functions with each other and external stimuli

35. Optic Chiasma
Region where the right and left optic nerves cross each other before entering the brain