Transcript Review Unit 3 Brain -Biology 2014-2015

Section A
Neural Communication: Neurons
• Neuron a nerve cell
– Sensory neurons (afferent Neurons) carry incoming
information from the sensory receptors to spinal cord or brain.
– Motor neurons (efferent neurons) carry outgoing information
from the brain and spinal cord to the muscles and glands.
– Interneurons neurons in the brain and spinal cord that
communicate between the sensory inputs and motor outputs.
Communication between sensory and motor neurons
Neurons
Parts of a Neuron:
Dendritethe bushy, branching extensions of a neuron that receive
messages from other neurons and conduct impulses toward
the cell body.
Axon messages pass to other neurons or to muscles or
glands.
Myelin sheath fatty tissue encasing the fibers of many neurons;
enables vastly greater transmission speed of neural impulses as
the impulse hops from one node to the next.
Multiple sclerosis=wearing down of Myelin Sheath
Terminal branches(end button, axon terminal, synaptic knobs) branched end of axon that contains neurotransmitters
Cell body (aka Soma)-contains nucleus and other parts needed to
sustain life
Neurons
Neurons
– Action potential firing of a neuron, a
neural impulse; a brief electrical charge
that travels down an axon
Action Potential
Neurons
• Firing of a neuron
– Depolarize=when axons allow info in and cause a
domino effect with axons
– Refractory period=inactivity after neuron had firedcan’t respond to stimulation, the inside of the cell
membrane is negative compared to the outside
– Excitatory neurotransmitters (chemicals released
from terminal buttons that excite next neuron to
fire)versus
– inhibitory (chemicals inhibit next button from
firing)
– Threshold a level of stimulation required to trigger a
neural impulse.
-All or none response-neurons fire completely or not
How Neurons Communicate
• Synapse = Synaptic gap = synaptic cleft-the junction between
the axon tip of the sending neuron and the dendrite or cell body of
the receiving neuron. The tiny gap at this junction is called the
synaptic gap or synaptic cleft.
• Neurotransmitters chemical messengers that cross the
synaptic gaps between neurons.
• Reuptake a neurotransmitter’s absorption
Into the terminal buttons of the sending neuron.
• Postsynaptic membrane/Pre-synaptic
membrane
How Neurons Communicate
How Neurotransmitters Influence Us
• Know ALL information in chart,
p.57 Plus:
Endorphins “opiate Like” linked to
pain control
How Neurotransmitters Influence Us
How Drugs and Other Chemicals Alter
Neurotransmitters
• Agonists versus antagonists
– Agonists
Mimics
neurotransmitter
– Antagonists
Blocks reuptake of
neurotransmitter
Introduction
• Nervous System is speedy and consists of all the nerve cells of the
peripheral and central nervous systems.
– Central Nervous System (CNS) the brain and spinal cord.
– Peripheral Nervous System (PNS) =Somatic (voluntary movement)
and Autonomic (automatic functions)
• Nerves= bundled axons
that form neural “cables”
connecting the
central nervous system
with
muscles
glands and
sense organs
The Peripheral Nervous System
Somatic Nervous System controls skeletal muscles.
• Also called the skeletal nervous system.
Autonomic Nervous System controls glands/muscles of the internal
organs (such as the heart). Its sympathetic division arouses; its
parasympathetic division calms.
The Nervous System-. 59 (Know these divisions)
The Central Nervous System
• Brain and spinal cord
Reflex a simple, autonomic
response to a sensory
stimulus such as the
knee-jerk response.
A Simple Reflex
Endocrine System-Contains Most Glands
Endocrine system the body’s “slow” chemical
communication system; a set of glands that
secrete :
Hormones into the bloodstream-longer lasting than
neurotransmitters
Adrenal glands a pair sit just above the kidneys and secrete
hormones (epinephrine and norepinephrine)
that arouse body in times of stress.
-Epinephrine a.k.a norepinephrine
-Adrenaline a.k.a. noradrenaline
Fight or flight response
Pituitary gland-endocrine system’s most influential gland.
Under influence of the hypothalamus, regulates growth
and controls other endocrine glands
The Brain-Part B
Introduction
• Lesion tissue destruction
is a naturally or
experimentally caused
destruction of brain tissue.
Neuroimaging Techniques
CT (Computed Tomography) or CATscan (xrays from dif.
Angels and combined by computer to give complete view)
PET Scan(Positron Emission Tomography) visual display
metabolic activity (chemical reactions that maintain life) of
brain -detects where a radioactive form of glucose goes
while the brain performs a given task.
MRI (Magnetic Resonance Imaging)revealing blood flow and
brain activity
fMRI (Functional MRI)show brain function.
Electroencephalogram (EEG)measures brain waves
Brain Functions-SEE Page 73
in Myers
The Brainstem
Brainstem is where
spinal cord swells as it enters
the skull; responsible for
automatic survival functions.
Medulla base of brainstem;
controls heartbeat and breathing.
Pons: controls facial expressions;
helps coordinate Movement
Thalamus sensory control center for
All senses but SMELL
Reticular formation nerve network in
brainstem through thalamus:
role in controlling arousal and focusing;
if does not function, we fall into deep
coma
The Cerebellum
• Cerebellum
–“Little brain”
processes sensory
input and coordinating
balance and voluntary
movement will help
from Pons
The Limbic System
Limbic System• doughnut-shaped neural
system -including the
Hippocampus: processes
memories
Amygdala: aggression and
emotions
(2 -lima bean sized)
Hypothalamus: emotions
and drives (hunger, thirst,
sex, body temp), reward center; helps governs endocrine
system via the pituitary gland
Introduction
• Cerebrum
– Cerebral cortex
Has about 20 billion nerve cells
and 300 billion synaptic
connections: interconnected
neural cells covering
cerebral hemispheres;
the body’s
ultimate control and
information-processing
center.
Functions of the Cortex
Association Areas
•
Association areas areas of the cerebral cortex that are not involved in
primary motor or sensory functions; are involved in higher mental
functions such as learning,
remembering, thinking, and
speaking. AA found in all 4 lobes
-Frontal lobes (judgment,
planning, process new
Memories-damage may remove
Inhibitions
• Phineas Gage (AP-look him up)
– Parietal lobes (math and spatial
reasoning-Einstein’s were large
and unusually shaped)
– Temporal lobes (recognize faces)
Structure of the Cortex
• Glial cells (“glue cells”) cells in the nervous system that support,
nourish, and protect neurons.
• Lobes:
1. Frontal lobes portion of cerebral cortex
lying behind the forehead; involved in
speaking, muscle movements
(motor cortex in rear of Frontal lobe),
Making plans and judgments
2. Parietal lobes top of the head and toward
the rear; receives sensory input for touch and
body position (via sensory cortex in front
of parietal lobe)
3. Occipital lobes at the back of the head; includes areas that receive
info. from visual fields
4. Temporal lobes above the ears; includes the auditory(hearing)
areas, each receiving info. primarily from opposite ear.
Language
• Aphasia impairment of language, usually caused by
left hemisphere damage either to Broca’s area
(impairing speaking) or to Wernicke’s area (impairing
understanding).
-Broca’s area (producing speaking)
– Wernicke’s area (understanding speech)
– Angular Gyrus-seeing/reading words
The Brain’s Plasticity
• Brain Damage
– Plasticitythe brain’s ability to
change, especially during
childhood, by reorganizing after
damage or by building new
pathways based on experience.
– Neurogenesis
the formation of new neurons/brain cells.
Splitting the Brain
– Corpus-callosum band of neural
fibers connecting the two brain
hemispheres and carrying messages
between them.
– Split brain isolates the brain’s two
hemispheres by cutting the fibers of
the corpus callosum connecting them.
Gazzaniga (key figure)-divided
brains of cats/monkeys
without serious effects
Right-Left Brain Differences
• Hemispheric Specialization
L controls R and visa versa
– Perceptual, spatial tasks-right
hemisphere
– Language-L
– Sense of self-R
– Read EmotionsR; motor skills R
Cognitive Neuroscience
• Cognitive neuroscience study
of the brain activity linked with
cognition (including
perception, thinking, memory
and language)
Section C- Genes: Our Codes for Life
• Chromosome=threadlike structures made of DNA molecules
that contain the genes.
• DNA=contains genetic information
that takes up chromosomes.
Genes=biochemical units of heredity
Recessive =(both parents need gene)
verses Dominant Trait =
(one parent needs gene)
Genome=shared genetic profile
Makes us human and not chimps
(or) Genetic make-up of an organism
Genotype is simply the information within a gene, or
the genetic makeup of a specific organism.
Examples of genotype:
• The gene responsible for eye color
• The gene responsible for hair color
• The gene responsible for height
• The gene responsible for how your voice sounds
• The gene responsible for certain diseases
• The gene responsible for certain behaviors
• The gene responsible for the size of a bird’s beak
• The gene responsible for the length of a fox’s tail
• The gene responsible for the color of stripes on a cat
• The gene responsible for the spots on a dog’s back
• The gene responsible for a person’s shoe size
Whereas genotype is the set of genes responsible for
a particular trait, phenotype is the physical
expression of that trait.
Examples of phenotype:
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Eye color
Hair color
Height
The sound of your voice
Certain types of disease
Certain behaviors
The size of a bird’s beak
The length of a fox’s tail
The color of the stripes on a cat
The size and shape of the spots on a dog’s back
An individual’s shoe size
Twins
Identical (monozygotic)Versus Fraternal
(dizygotic)Twins
Dad determines a child’s sex
mother gives us X (female) chromosome
dad gives either another X or a Y (male
chromosome)
XX=girl; XY=boy
Sex chromosomes are the 23rd pair (46
chromosomes total-23 from mom and 23
from dad) of chromosomes
Up until 7 weeks after conception, you are
anatomically (genital) neutral
Mutation
= the random error in gene replication that
leads to a change.
Example=color blindness
Genome
= the complete instructions for making an
organism, consisting of all the genetic
material in that organism’s chromosomes.
Genetic make-up of an organism
Identical Twins
= twins who develop from a single fertilized
egg that splits in two, creating two
genetically identical organisms.
Fraternal Twins
= twins who develop from separate fertilized
eggs. They are genetically no closer than
brothers and sisters, but they share a fetal
environment.
Heritability
= the proportion of variation among
individuals that we can attribute to genes.
The heritability of a trait may vary,
depending on the range of populations
and environments studied.