Neurons, Hormones, and the Brain
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Transcript of Neurons, Hormones, and the Brain
Neurons, Hormones, and the Brain The central nervous system The peripheral nervous system Communication in the nervous system Neurotransmitters Mapping the brain A walk through the brain The two hemispheres of the brain Where is the self? Are there “his” and “hers” brains?
The Central Nervous System
Brain Spinal cord
A collection of neurons and supportive tissue running from the base of the brain down the center of the back.
Protected by spinal column.
Peripheral Nervous System Somatic
Includes the nerves that are connected to sensory receptors and skeletal muscles.
Autonomic The sympathetic nervous system mobilizes bodily
resources and increases the output of energy during emotion and stress.
The parasympathetic nervous system operates during relaxed states and that conserves energy.
Communication in the Nervous System The structure of the neuron
Different kinds of neurons How neurons communicate
Action potential Chemical messengers in the nervous system
Neurotransmitters Major neurotransmitters Endorphins
Endocrine system Hormones
Structure of a Neuron Dendrites
receive information from other neurons and transmit towards the cell body.
Cell body keeps the neuron alive and determines
whether it will fire.
Axon extending fibre that conducts impulses
away from the cell body and transmits to other cells.
Neurons in the News Canadian research has provided evidence for
neurogenesis: the production of new neurons from immature stem cells.
Stem cells are immature cells that renew themselves and have the potential to develop into mature cells; given encouraging environments, stem cells from early embryos can develop into any cell type.
How Neurons Communicate Axon terminals release
neurotransmitter. Neurotransmitter enters
synaptic gap. Neurotransmitter binds
to receptors that it fits.
Action Potential A brief change in electrical voltage which occurs
between the inside and outside of an axon when a neuron is stimulated. It produces an electrical impulse.
Neurotransmitter A chemical substance that is released by a
transmitting neuron at the synapse and that alters the activity of a receiving neuron.
Major Neurotransmitters Serotonin Dopamine Acetylcholine (ACh) Norepinephrine Gamma amino butryic acid (GABA) Glutamate Endorphins
The Endocrine System Endocrine glands
release hormones into the bloodstream.
Hormones regulate growth, metabolism, sexual development and behaviour, and other functions.
Hormones: Long Distance Messengers Melatonin Adrenal Hormones
Cortisol, epinephrine, and norepinephrine. Sex Hormones
Androgens, estrogens, and progesterone.
Mapping the Brain Lesion method Electroencephalogram (EEG) Transcranial magnetic stimulation (TMS) Positron-Emission tomography (PET) Magnetic resonance imaging (MRI)
Mapping the Brain
Lesioning Involves damaging and removing sections of
brain in animals, then observing their effects. Transcranial magnetic stimulated (TMS)
Stimulates brain cells using a powerful magnetic field produced by a wire coil placed on the head.
Can be used to temporarily inactivate neural circuits.
Positron Emission Tomography (PET) A method for analyzing biochemical activity in the
brain, using injections of a glucose-like substance containing a radioactive element.
Active areas have increased blood flow.
Sensors detect radioactivity.
Different tasks show distinct activity patterns.
Magnetic Resonance Imaging (MRI) Method for studying body and
brain tissue. Magnetic fields align certain
ions and compounds. When field is removed, these
molecules release energy as radio waves.
Computer calculates tissue density from radio waves.
Provides clear, 3D images.
A Walk Through the Brain The brain stem The cerebellum The thalamus The hypothalamus and the pituitary gland The amygdala The hippocampus The cerebrum and lobes of the cerebral cortex
The Brain Stem Pons
involved in sleeping, waking and dreaming.
Medulla responsible for certain automatic
functions such as breathing and heart rate.
Reticular activating system (or formation) arouses cortex and screens
incoming information.
The Cerebellum Regulates movement and
balance. Involved in remembering
simple skills and acquired reflexes.
Plays a part in analyzing sensory information, solving problems and understanding words.
The Thalamus Relays sensory messages to the cerebral cortex. Includes all sensory messages except those from
olfactory bulb.
Hypothalamus and Pituitary Gland Involved in emotions and
drives vital to survival including fear, hunger, thirst, and reproduction.
Also regulates autonomic nervous system.
The pituitary gland is a small endocrine gland which releases hormones and regulates other endocrine glands.
Pituitary Gland
The Amygdala Responsible for arousal
and regulation of emotion and the initial emotional response to sensory information.
Plays important role in mediating anxiety and depression.
The Hippocampus Responsible for the
storage of new information in memory.
Compares information with what the brain has come to expect about the world.
“Gateway to memory” because it enables us to navigate through the environment.
The Cerebrum Largest brain structure. Consists of upper part of brain and divided into
two cerebral hemispheres which are connected by the corpus callosum.
In charge of most sensory, motor and cognitive processes.
Surrounded by cerebral cortex, a collection of several thin layers of cells (gray matter).
Lobes of the Cerebral Cortex Occipital lobes
Visual cortex.
Parietal lobes Somatosensory cortex.
Temporal lobes Memory, perception, emotion and auditory cortex. Left lobe, Wernicke’s area.
Frontal lobes Emotion, planning, creative thinking and motor cortex. Left lobe, Broca’s area.
Phineas Gage Gage was a railroad
construction foreman An 1848 explosion forced
a steel tamping rod through his head
Others said he was “…no longer Gage…”
Lost his job, worked as a sideshow exhibit
The Corpus Callosum Millions of myelinated
axons connecting the brain’s hemispheres.
Provides a pathway for communication between the hemispheres.
If surgically severed for treatment of epilepsy, hemispheres cannot communicate directly.
Split-Brain Experiment Subjects were presented information to one or the
other side of their brains. Patients identified verbally the pictures to the right
(i.e., boy). When asked to point to the face seen, the patients
pointed to the left picture.
Where Is the Self? Most scientists assume that what we call “mind,”
“consciousness,” self-awareness,” or “subjective experience” can be explained in physical terms as a product of the brain.
Some contend that the brain consists of independent modules and that the self is an illusion.
No one understands yet how subjective experience is linked to physical processes in the brain.
Are There “His” and “Hers” Brains? After analyzing 49 studies of sex differences in
brain anatomy, Canadian researchers found small differences between the two groups and larger differences within groups.
There does appear to be sex differences in lateralization of language. Males show left hemisphere activation only. Females, left and right.
There also appears to be differences in amounts of grey matter. Females have more.