Transcript BI 201 Human Anatomy & Physiology

BI 201 Human Anatomy & Physiology
How do cells communicate throughout the body?
Membranes & Receptors
Chemical compounds & electricity
are the medium through which,
cells communicate!
• Analogous with information
sent via electrical pulses.
Ex. email
• Information sent as “actual”
messages (letters etc.) rather than
“virtual” such as hormones
BI 201 Human Anatomy & Physiology
How do receptors respond only to the proper
signal?
• Chemical signals called
____________
• ____________ are
molecules with a special
spot for the ligand to bind
to called either a ________
____ or a ___________
_____.
• __________! ~ Lock and
Key theory
BI 201 Human Anatomy & Physiology
If I had 2 ligands, one that
was water soluble and one
that was lipid soluble.
Which one could enter a
cell and interact with an
“intracellular receptor”?
?
?
What if there were two
molecules, one very large
one and one very small
one, which one might be
restricted to interacting
with “membrane bound
receptors”?
BI 201 Human Anatomy & Physiology
How can a membrane bound receptor affect
change on the inside of a cell?
Ligands bound with membrane
bound receptors cause one of
three reactions:
1)
2)
3)
BI 201 Human Anatomy & Physiology
Changing membrane permeability will do what
to the inside of a cell?
The protein with the
receptor site can be
part of a _________
_________.
When the ligand
bonds, it changes the
______ (and hence
function) of the
channel protein
BI 201 Human Anatomy & Physiology
What if the receptor doesn’t have a channel?
G proteins
(bond with
guanine
nucleotides)
3 subunits:
Alpha
Beta
Gamma
1.
3.
2.
4.
Activated (GTP) Alpha subunit activates a response
BI 201 Human Anatomy & Physiology
What if the receptor doesn’t have any Gproteins?
Receptor proteins
can activate or
alter activity of
__________
_______.
An example is
____________
such as what
happens when
insulin binds with
receptors.
BI 201 Human Anatomy & Physiology
How do intracellular receptors function?
Some ligands
diffuse into cell
and interact with
_________ or
____ itself. DNA
is code for
specific proteins
which, are the
cell’s response
Ex. __________
& 2ndry sex char.
BI 201 Human Anatomy & Physiology
Take 5!!!
Some drugs produce rapid responses,
which disappear shortly after the drug
is no longer present. Other drugs
require many hours before a response
is seen, and the effects of the drug take
days or longer to disappear once the
drug is discontinued. Why is one of
these drugs is more likely to influence Discuss with your
intracellular receptors and the other is neighbor and predict
more likely to influence membranean answer.
bound receptors?
BI 201 Human Anatomy & Physiology
How do different receptors result in response?
Hormone
Cell Response
BI 201 Human Anatomy & Physiology
How does the body generate electric potential?
Electric signals (called
_______________) are
essential to nerve cell
function and muscle
contraction.
Refer to tables 11.2, 3 & 4
BI 201 Human Anatomy & Physiology
How does the body maintain electrical
gradients?
_________ with “-” charge
stuck inside cells
• __________ channels
that allow K+ to diffuse in Non-gated
or out of the cell
• Very few Na+ ions can
diffuse through cell
membrane EXCEPT via
_____________
• ___________ contributes
to gradient
Gated
BI 201 Human Anatomy & Physiology
How does the body maintain electrical
gradients?
•As K+ diffuse out they
leave ____________ inside
the cell and develop an
electric potential. When
the “-” attraction inside the
cell is = to the tendency for
K+ to leave then
__________ is established.
•Usually around -70 to -90
mVolts… called _______
___________
BI 201 Human Anatomy & Physiology
What are the 2 primary ways to change the
resting potential?
1)
2)
Decrease potential…
_____________
(hypopolarization)
Increase potential…
_____________
BI 201 Human Anatomy & Physiology
Take 5!!!
What would the effect on the resting
membrane potential be if the
permeability of the plasma membrane
to K+ was reduced? Why?
Discuss with your
neighbor and predict
an answer.
BI 201 Human Anatomy & Physiology
What is the effect on the resting potential that results
from changing Na+ concentrations?
Change in Na+ ion
concentration
DOESN”T have
much effect
Change in
permeability DOES
Why?
BI 201 Human Anatomy & Physiology
What properties make some cells electrically excitable?
Cells such as muscle and
nerve cells have >#...
Depolarization causes the ___
channels to open quickly…
(___ open more slowly and
close more slowly)
BI 201 Human Anatomy & Physiology
What about the effects of Ca2+ ions on the
resting potential?
When extracellular
Ca2+ ions are reduced
then they _________
_____ ______
(including gated Na+
channels, which causes
them to open).
What is the result of
Hypocalcemia?
Ca 2+
BI 201 Human Anatomy & Physiology
Are there any potentials other than resting
potentials?
A localized stimulus usually causes… a _____
_______ (change in resting membrane potential).
Can be caused by:
1)
2)
3)
4)
5)
BI 201 Human Anatomy & Physiology
What are the properties of local potentials?
Changes in the
resting potential
can be at
different levels
of magnitude,
i.e. ________
Influence of
local potentials
can be
increased by
___________
Local potentials taper off as they move
away from the stimulus source
(see table 11.3)
BI 201 Human Anatomy & Physiology
Do local potentials have any potential?
If the threshold potential is
reached… then an _______
_________ results
3 phases:
These are propagated along
the plasma membrane and
are “_____________”
Below the threshold = local
potential ~ “______”
Above the threshold =
action ~ “______”
(see table 11.4)
BI 201 Human Anatomy & Physiology
How do those waves correlate with cellular
reality?
BI 201 Human Anatomy & Physiology
What happens after all the excitement?
Refractory period
Until the voltage gated
channels return to the
resting state, no further
action potential is possible.
When totally
insensitive…then ________
__________ _________
BI 201 Human Anatomy & Physiology
How do action potentials move along a cell?
What keeps
the action
potential
from
reversing
direction?
BI 201 Human Anatomy & Physiology
What about getting the electrical “message”
(action potential) to the next cell?
Generally accomplished
via _________ _________
If ligand opens Na+
channels then…
If ligand opens K+
channels then…
BI 201 Human Anatomy & Physiology
What about getting the electrical “message”
(action potential) to the next cell?
Cardiac & smooth muscle
tissue have _________
____________.
Action potentials can be
propagated across
adjacent cells via the ___
_________, which allow
ions to pass through.
BI 201 Human Anatomy & Physiology
Do all neurons respond to continued
stimulation equally?
Some neurons will
continue to maintain a
local potential sufficient
to initiate action
potentials.
other neurons begin to
become insensitive to
continued stimulus and
the frequency drops off
until the local potential
drops below threshold
(_____________).