THE BIOLOGY OF THE MIND!
NEURAL COMMUNICATION
• Our bodies neural information system is complexity built from simplicity
• Neuron – nerve cells
• Sensory neurons – carry messages from the body’s tissues and sensory
organs inward to the brain and spinal cord, for processing
• Motor neurons – neurons that carry outgoing information from the brain
and spinal cord to the muscles and glands
• Interneurons – located inside the brain and intervene between the
sensory neurons and the motor neurons
WHAT DOES A NEURON LOOK LIKE?
• All neurons are essentially based off of the same cell body
• Dendrites receive information whereas the axons passes the message along –
Axons speak, dendrites listen
• The Myelin Sheath insulates the axons and helps speed up their impulses
ACTION POTENTIAL
• Action potential is a neural impulse. It is a brief electric charge that
travels down an axon.
HOW DO NERVE CELLS COMMUNICATE WITH OTHER
NERVE CELLS?
• Neurons interweave and meet at a point in between themselves called a
synapse.
• When an action potential reaches the knoblike terminals at an axon’s end, it
triggers the release of chemical messengers, called neurotransmitters.
• Within 1/10,000th of a second, the neurotransmitter molecules cross the
synaptic gap and bind to the receptor sites of the receiving neuron
• Reuptake then occurs in which the neuron reabsorbs the excels
neurotransmitters.
NEURON VIDEO
• http://www.youtube.com/watch?feature=player_embedded&v=o9p2ou1IyC0
THE NERVOUS SYSTEM
• Nervous System: the body’s speedy, electrochemical
communication network, consisting of all the nerve cells of the
peripheral and central nervous systems.
• Central Nervous System: the brain and the spinal cord.
• Peripheral Nervous System: the sensory and motor neurons that connect the
central nervous system to the rest of the body.
THE PERIPHERAL NERVOUS SYSTEM
• Contains two systems: somatic and autonomic.
• Somatic Nervous System: enables voluntary control of our skeletal muscles (example:
turning a page in a book)
• Autonomic Nervous System: controls our glands and muscles of our internal organs,
influencing such functions as glandular activity, heartbeat, and digestion.
• Within the autonomic nervous system there are two divisions which serve two important
functions
• Sympathetic Nervous System: arouses the body, mobilizing its energy in stressful situations
• Parasympathetic Nervous System: conserves energy, calms you down, decreases heartbeat
THE CENTRAL NERVOUS SYSTEM
• Composed of the brain and the spinal cord, there are 40 billion neurons running through the CNS. There
are about 400 trillion synapses in the human body.
• The brain’s neurons cluster into work groups called neural networks. Neurons that fire together, work
together.
• The spinal cord is an information highway connecting the peripheral nervous system to the brain. The
spinal cord runs the reflexes, which are simple, automatic responses to a sensory stimulus.
•
Examples: knee-jerk, heat reflex, arousal
THE ENDOCRINE SYSTEM
• Endocrine System: the body’s “slow” chemical communication system; a set
of glands that secrete hormones in the bloodstream.
• Hormones: chemical messengers that are manufactured by the endocrine glands. –
travel through the bloodstream and affect other tissues
• When hormones act on the brain they influence our interest in aggression, food, and sex.
GLANDS
• Adrenal Gland: a pair of endocrine glands that sit just above the kidneys and secrete hormones
(epinephrine and norepinephrine) that help arouse the body in times of stress
• Pituitary Gland: the endocrine system’s most influential gland. Under the influence of the
hypothalamus, the pituitary regulates growth and controls other endocrine glands.
• Feedback System BRAIN -> PITUITARY -> OTHER GLANDS-> HORMONES -> BRAIN
THE BRAIN
• Brain + body = mind
•
The effect of hormones on experiences such as love reminds us that we would not be the same mind if we
were a bodiless brain.
•
If all of your organs were transplanted, you would be much the same person, unless one of these organs was
your brain
LOWER LEVEL BRAIN STRUCTURES
1) THE BRAINSTEM
• Begins where the spinal cord swells slightly after entering the skull. The slight swelling is the medulla,
above that is the pons, and the midbrain.
• The brainstem controls breathing, digestion, heart rate, and other automatic processes, as well as
connecting the brain with the spinal cord and the rest of the body.
2) THE THALAMUS
• Sensory switchboard – controls all the senses except smell and routes it to the higher brain regions that
deal with seeing, hearing, tasting, and touching.
3) CEREBELLUM
• Means “little brain” - The Cerebellum helps us judge time, modulate our emotions, and discriminate
sounds and textures – it also coordinates voluntary activity
THE LIMBIC SYSTEM
1) THE AMYGDALA
• In the limbic system, it consists of two lima bean-sized neutral clusters
• The amygdala influences aggression and fear, processes emotional memories
2) THE HYPOTHALAMUS
• Just below the thalamus is the hypothalamus
• Influences memory function – long and short term memory – as well as monitors blood chemistry to
keep the internal environment in a steady state – can also take orders from the brain to trigger
hormones
3) THE CEREBRUM
• Makes up 75% of the brain by volume and 85% by weight – is divided by a large groove called the
longitudinal fissure, into two distinct hemispheres which control the left and right sides of the body
4) CEREBRAL CORTEX
• Covers the cerebrum, is a sheet of neural tissue which is only 2-4 millimeters thick, which serves as the
brains control and information processing center - it plays a key role in memory, attention, perceptual
awareness, thought, language, and consciousness.
• It envelops other brain organs such as the thalamus and hypothalamus and relays information
• The cerebral cortex contains six distinctive and interconnected layers, which are grooved and folded,
allowing a large surface area to fit in the confines of the skull. Folds are called gyri and the grooves are
called sulci.
MOTOR CORTEX VS. SENSORY CORTEX
• The motor cortex is an area at the rear of the frontal lobes that controls voluntary movements.
• The sensory cortex is an area at the front of the parietal lobes that registers and processes body touch
and movement sensations.