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Ch 46-47 Wrap-up

Urchin
Gastrulation

( proto or deuterostome ? )

Triploblastic
(know 3 layers/colors)

Archenteron,
blastocoel
Nerve cord?
Notochord?
 Primitive streak


What structure(s)
does each layer
give rise to?

Organogenesis
(differentiation)
happens very early
Table 47.1
GERM LAYER
ECTODERM
ENDODERM
MESODERM
p. 945
Organs and tissues
formed
Skin, cornea and lens of
eye, nervous system
(neural tube), mouth and
rectum
Digestive tract lining,
respiratory system lining,
many organs
Notochord, skeleton,
muscles, circulatory
systems, reproductive
system, excretory
system
Ch. 48
Nervous Systems
Nervous
system
afferent
interneurons
efferent

PNS, CNS
INPUT:
Effector cells
Sensory Neurons (receptors)
INTEGRATION: CNS(brain & spinal cord) Interneurons
OUTPUT: Motor Neurons (effectors)
The Reflex Arc
The Neuron






Dendrites receive
the signal, axon
delivers the signal
away to another
neuron or to the CNS
Myelin sheaths (white matter) insulate the axon and
are made by Schwanns cells or oligodendrocytes.
Schwanns and Oligodendrocytes are both types of
supporting cells called glia.
What is saltatory conduction? P.970
What is a Node of Ranvier?
What is a synapse?
Anatomy of a Neuron
Makes myelin - PNS
>Speed of Transmission: Larger axons
& Myelin sheath (Saltatory conduction)
Outside
is always
zero
Less (+)
inside =
“-” inside
and “+”
outside
-70 mV is the resting
membrane potential

What makes a signal travel down the
axon ?
0
Action Potential
(“all or none” nerve
impulse)
K+ out of
EPSP
the cell
-50
Threshold Potential reached: -50
-70
Membrane potential (mV)
+35
Na+
into the
cell
Na/K pump restores
Hyperpolarization
from ___ ions
0
1
2
3
4
Time (milliseconds)
resting state
restored (-70)
Hyperpolarization:
more negative inside
by K+ moving out—does
not cause an action potential
Depolarization: inside gains more
positive charge by Na+ rushing in
EXCITATORY (+)
-70
What is meant by all–or–none action potential?
The steps of an action potential…
Resting State
+
Na
gates closed,
K+ gate closed
Na/K pump is maintaining –70mV
Depolarizing
Phase
Na+ gate OPENS, (fast gate)
+
K channels are still closed
(slow gate)
Na+ rushes into the neuron (+ + + +)
RE-polarizing
Phase
+
Na
inactivation gate closes,
K+ slow gate OPENS
K+ rushes out of the neuron
Undershoot
+
Na
channels closed,
K+ channels still OPEN
K+ still rushes out of the neuron
(Hyperpolarizing the inside - - - - - -)
Direction of
transmission?
Slow closing of
the K+ channels
prevents “backflow”
One way flow
of Electricity!
Chemical synapses

TERMS:

Vesicles
synaptic cleft
neurotransmitters
(Ca2+)
receptor
ion channel
Pre/post
synaptic
membrane
Enzymes to
degrade the
neurotransmitters

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

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Summation of IPSP & EPSP
Inhibitory(-) & Excitatory(+) Post-Synaptic Potential
Temporal and Spatial Summation
PNS
AUTONOMIC

Sympathetic

Stress (like

Parasympathetic

Peace
a “fight or
flight”
response)
(relaxed,
normal
functions)
The real thing . . . . . . . .
Cerebrum
Thalamus
Hypothalamus
Cerebellum
Brain stem: medulla
oblongata, pons, midbrain
Cerebrum
Right versus left Cerebrum
BRAIN STRUCTURES
AND FUNCTIONS

Brain Stem:

Medulla Oblongata & Pons = (autonomic,
homeostatic, data conduction)
 Midbrain = (receives and integrates sensory
information)
 Cerebellum: Automatic coordination of movements



and balance
Thalamus:integration of stimuli coming to the brain
Hypothalamus: important homeostatic regulation
(temperature, hunger, thirst) & hormones
Cerebrum: memory, learning , emotions, motor
movements, sensory cortex areas