The Human Brain

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The Human Brain

• Ranges from 750 cc to 2100 cc
• Contains almost 98 of the bodys neural tissue
• Average weight about 1.4 kg (3 lb)

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Can You Label the Brain?
Motor Cortex
Sensory Cortex
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Parietal Lobe
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Frontal Lobe
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Occipital Lobe
Temporal Lobe
Cerebellum
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Reticular Activating System
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Spinal Cord
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three layers of meninges around the brain and
spinal cord.
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• 1. Cerebrum
• Largest part of brain
• Controls higher mental functions
• Divided into left and right cerebral hemispheres
• Surface layer of gray matter (neural cortex)

• Neural Cortex
• Also called cerebral cortex
• Folded surface increases surface area
• Elevated ridges (gyri)
• Shallow depressions (sulci)
• Deep grooves (fissures)

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• 2. Cerebellum
• Second largest part of brain
• Coordinates repetitive body movements
• 2 hemispheres
• Covered w/ cerebellar cortex

• 3. Diencephalon
• Located under cerebrum and cerebellum
• Links cerebrum with brain stem

4. Mesencephalon Also called midbrain Processes
sight, sound, and associated reflexes Maintains
consciousness
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The Diencephalon

• Thalamus, epithalamus, and hypothalamus

• Integrates sensory information and motor commands

• Pineal Gland in posterior epithalamus
• Secretes hormone melatonin

• Thalamus Post Office
• Filters ascending sensory information for primary
  sensory cortex

Figure 145a
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thalamus(80 of diencephalon), hypothalamus,
epithalamus.
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Brain Structure Hindbrain

• Hindbrain (Old Brain)
• (Reptilian Brain)
• Spinal cord, lower brain stem, and cerebellum
• Medulla Oblongata
• Located where the spinal cord enters the skull
• Breathing, posture

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Brain Structure Hindbrain

• Cerebellum
• Extends from rear of hindbrain
• Motor control
• Pons
• Bridge in hindbrain
• Sleep and arousal

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Brain Structure Midbrain

• Midbrain
• Between midbrain forebrain
• Relays information between the brain and
  eyes/ears
• Reticular Activation System
• RAS
• Stereotyped patterns of behavior
• Walking, sleeping, automatic functions

Basal ganglia Starting and stopping voluntary
movements
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Brain Structure Limbic SystemInstinctual Brain

• Limbic system
• Plays an important role in both memory and
  emotion
• Amygdala
• Discrimination of objects and emotion Angry Amy
• Hippocampus
• Storage of memories
• BIG Campus Library!

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Brain Structure

• Hypothalamus
• Monitors eating, drinking, sex, temperature
• Helps direct the endocrine system through the
  pituitary gland
• Involved in emotion, stress, and reward

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8 Functions of the Hypothalamus

1. Provides subconscious control of skeletal muscle
2. Controls autonomic function
3. Coordinates activities of nervous and endocrine
   systems

1. Secretes hormones ADH(Antidiuretic) OT
   (Oxytocin)

• Produces emotions and behavioral drives
• the feeding center (hunger)
• the thirst center (thirst)

1. Coordinates voluntary and autonomic functions
2. Regulates body temperature

1. Controls circadian rhythms (daynight cycles)

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Sensory Areas

• Postcentral gyrus of parietal lobe
• receives somatic sensory information (touch,
  pressure, pain, vibration, taste, and
  temperature)
• Primary sensory cortex
• surface of postcentral gyrus

Central sulcus separates motor and sensory areas

• Visual cortex
• information from sight receptors
• Auditory cortex
• information from sound receptors
• Olfactory cortex
• information from odor receptors
• Gustatory cortex
• information from taste receptors

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Neocortex..NEWBRAIN

• Occipital lobe ..SIGHT
• Back of the head
• Vision
• Temporal lobe
• Just above the ears
• Hearing,Speech

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Neocortex

• Frontal lobe
• Behind the forehead
• Purposeful control of voluntary muscles
• Intelligence, Cognition
• Parietal lobe
• Top of the head, toward the rear
• Processing bodily sensations
• Motor Cortex
• Somatosensory Cortex

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Right Hemisphere Radical, Religious, Random,
Roundabout ways
Left Hemisphere Language, Linear, Logical
Corpus Callosum
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Brain Protection and Support

• Physical protection
• bones of the cranium
• cranial meninges
• cerebrospinal fluid
• Biochemical isolation
• bloodbrain barrier

• Cranial Meniges - 3 layers
• dura mater
• arachnoid mater
• pia mater
• Is continuous with spinal meninges
• Protects the brain from cranial trauma

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4 Breaks in the BBB

• Portions of hypothalamus
• secrete hypothalamic hormones
• Posterior lobe of pituitary gland
• secrete hormones ADH and oxytocin

• Pineal glands
• pineal secretions
• Choroid plexus
• where special ependymal cells maintain bloodCSF
  barrier

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Brain Damage
Phineas Gage

• Plasticity
• The brains capacity to modify and reorganize
  itself following damage
• Collateral sprouting
• Axons of healthy neurons adjacent to damaged
  cells grow new branches
• Substitution of function
• Damaged regions function is taken over by
  another area, or areas, of the brain

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Studying the Brain

• Electroencephalograph (EEG)
• Records the electrical activity of the brain
• Computer-assisted axial tomography (CAT scan)
• 3D imaging obtained from X rays of the head
• Magnetic resonance imaging (fMRI)
• Magnetic field around the body

• PET Positron Emission Tomograpy
• Color images of hot cold actions

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The Endocrine System

• Endocrine Glands
• Release their chemical products, called
  hormones, directly into the bloodstream
• Pituitary gland
• Controls growth and regulates other glands
• Adrenal glands
• Play an important role in our moods, energy
  level, and ability to cope with stress
• Thyroid Gland Growth
• Gonads Sex Characteristics

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Autonomic nerves (in blue)--sympathetic and
parasympathetic--regulate much of the body
without our conscious knowledge. Sympathetic
nerves branch from spinal nerves (in white) and
form a chain of ganglia that sends fibers to the
organs. Parasympathetic nerves, including the
important vagus, usually reverse the action of
sympathetic ones.