Chp.45: Hormones & the Endocrine System (review: Chp.11 Cell
Communication)
Thurs. 3/6Collect: LabToday: Test, INB check, Cell Communication
POGILHomework: Signal Transduction POGIL(print from my.ccsd.net),
Print out notes for Ch. 40 for next class, Guided Reading-Ch.
40.Next class: Ch 40.Test Corrections must be done by Thurs.
3/13
Pg. 144Ch 40 Guided ReadingPg. 145Ch 40 EK Paragraph3D2 or
3D3In: pg. 146 Watch video clip: Bozeman Cell
Communication.Complete Video Guide and tape in.Cell Communication
POGILComplete ONE copy in groups of 3-4 and turn in at end of
period.Pg. 147Signal Transduction POGILPrint out the Signal
Transduction POGIL from my.ccsd.net, complete and turn in next
class. It will go on this page when returned.OutWhy is cellular
communication is important for:Unicellular organisms?Multicellular
organisms?Mon. 3/10Collect: Signal Transduction POGIL and Guided
Reading-Ch 40Today: Finish Cell Comm. POGIL, Notes-Ch 40Homework:
Endocrine diagrams and Guided Reading-Ch 37. Print Ch. 37
powerpoint for next class.Next class-Quiz-Ch 40Test corrections by
Thursday!!!In: pg 148What is the difference between and endocrine
gland and exocrine gland? Give an example of each.Pg. 149Chp.40:
Hormones & the Endocrine System
Remember:Why cells need to communicate:Coordinate activities in
multicellular organismsHormone actionsCell recognitionTo find mates
(yeast cells)Turn pathways on/offapoptosis
10Coordinate activities such as development and movement,
hormones and neurotransmitters are chemical communications, cell
recognition such as for antibodies, yeast exchange mating factors,
pathways such as signal transduction pathway that are a series of
steps by which a signal on the cells surface is converted to a
specific cellular response, and apoptosis is a type of programmed
cell death (think embryonic development of fingers and toes, the
disappearance of a tadpoles tail, etc.), just to name a
few.10Evolutionary ties of cell communicationCell-to-cell
communication is everywhere in biological systems from Archaea and
bacteria to multicellular organisms.
The basic chemical processes of communication are shared across
evolutionary lines of descent.
Signal transduction is an excellent example
1111Signal Transduction AnimationClick on this link to access
the
animation:http://www.wiley.com/college/boyer/0470003790/animations/signal_transduction/signal_transduction.htm
12At this point, we just want to introduce the concept of signal
transduction. Preface this animation with a brief discussion of the
fight or flight response. Imagine observing a bear in its natural
habitat is an appropriate introduction, then click on the animation
link. Only explore the overview portion of the animation at this
time. 12Chemical Communication13Pheromones are chemicals that are
produced by organisms to aid in communication by members of the
same species, quorum sensing is used by organisms to react as a
group usually in bacteria.
13Pheromones14Members of the same animal species sometimes
communicate with pheromones, chemicals that are released into the
environment.
Pheromones serve many functions, including marking trails
leading to food, defining territories, warning of predators, and
attracting potential mates.
The video shows a gentleman laying down a PaperMate Ink trail on
a plain white piece of paper. Next, he places a termite onto the
paper and within seconds the termite follows the trail (with a bit
of trial and error on the termites part). Students love this!
14Quorum sensing Quorum sensing in bacteria single celled bacteria
monitor their environment by producing, releasing and detecting
hormone-like molecules called autoinducers.
15
This process, termed quorum sensing, allows bacteria to monitor
the environment for other bacteria and to alter behavior on a
population-wide scale in response to changes in the number and/or
species present in a community. THERE IS NO NEED TO DESCRIBE THE
DETAILS of the image shown.
15Chemical Communication16This flow chart shows a simplified
classification system for the cell communication occurring within
the body. The dividing lines between hormones, paracrine and
autocrine signals have blurred. In our study of hormones we will
mostly focus on hormones as long distance communicators. Paracrine
refers to a secreted molecule that acts on a neighboring cell,
autocrine refers to a secreted molecule that acts on the cell that
secreted it.16Direct Contact CommunicationEx. Plant cells
communicate directly through openings called plasmodesmata.
17
Another example would be helper T cells bind with Killer T cells
in the immune system.17Short Distance CommunicationParacrine
signals diffuse to and affect nearby cellsEx. NeurotransmittersEx.
Prostaglandins18
The next four slides outline the different categories of cell to
cell communications involved in the endocrine system. Students
should know an example for each one as well as the basics of how
each type of communication works.
Paracrine chemical signals work in cells that are near the
secreting cell. For example, neurotransmitters released by a
presynaptic cell move across the synapse and impact the post
synaptic cell.
In the immune system, prostaglandins promote fever and
inflammation and intensify the sensation of pain.Prostaglandins
help regulate aggregation of platelets, an early step in formation
of blood clots.
18
SynapseResponseResponseNeuronSynaptic
signalingNeurosecretorycellBloodvesselNeuroendocrine
signalingNeurotransmitters and Neurohormones19 Intercellular
communication by secreted molecules.Autocrine signalsThese
chemicals affect the same cells that release them. Ex.
Interleukin-1 produced by monocytes and can bind to receptors on
the same monocyte.Tumor cells reproduce uncontrollably because they
self-stimulate cell division by making their own division
signals.
20
Againstudents need to become an expert on an example while have
knowledge of various examples. 20Long Distance
CommunicationEndocrine hormones via signal transduction
pathway:21
The word transduce means to convert. A signal transduction
pathway converts the original signal molecule into a cellular
response. This conversion requires several intermediate messenger
molecules (sometimes called second messengers), so the signal is
actually converted or transduced several times, as shown in the
blue box above labeled Transduction. The concept of signal
transduction pathways will be seen over and over again in AP
Biology and is certain to be on the exam.21HormonesEndocrine glands
produce hormones which areChemical signalsTransported in tissue
fluidsDetected only by target cells22
Ask students to name some hormones. Testosterone and estrogen
are sure to be in their list! Either of those make perfect expert
examples. 22Summary:23
Allow students to correct their misconceptions before moving on.
It would be great if they could leave class with a complete and
ACCURATE concept map!23Communication FeaturesSecreting cell -
releases the signal
Signal = chemical = ligand
Receptor - accepts and temporarily joins with the ligand forming
receptor/ligand complex
Target cell contains the receptor 24
A ligand is in a narrow sense, a signal triggering molecule,
binding to a site on a target protein. The word binding refers to
intermolecular forces (IMFs) rather than an actual chemical
(covalent or ionic) bond. While actual chemical bonds can form, it
is very rare. It is far more common for the binding to be more of
an electrostatic attraction. You can demonstrate this for students
using small pieces of torn paper and an ordinary comb. Charge the
comb by combing it through someones hair (ions from the keratin
protein of hair will adhere to the plastic comb). The comb will
then attract the small pieces of paper. It is obvious that these
attractions are not actual chemical bonds.
Historical note: In 1970, Dr. Martin Rodbell examined the
effects of glucagon on a rat's liver cell membrane receptor. He
noted that guanosine triphosphate disassociated glucagon from this
receptor and stimulated the G-protein, which strongly influenced
the cell's metabolism. Thus he deduced that the G-protein was a
transducer that accepted glucagon molecules and affected the cell.
For this he shared the 1994 Nobel Prize in Physiology or Medicine
with Dr. Alfred G. Gilman.
Dr. Gilman became Chairman of the Department of Pharmacology at
the University of Texas Southwestern Medical Center in 1981 and
then in 2006 he became Executive Vice President for Academic
Affairs and Provost of the University of Texas Southwestern Medical
Center in Dallas, TX. In short, he is a teacher as well as a Nobel
Prize Winner! He has worked with the NMSI science staff on several
teacher training projects including the development of a virtual
microscope. He is a long standing supporter of LTF and of NMSI and
an advocate of science education. 24Apply the featuresInsulin is
secreted by beta cells of the pancreas. Once secreted, insulin
travels around the body. When insulin docks with an integral
protein on the membrane of a muscle cell, glucose can enter the
cell.
What is the secreting cell, the target cell, ligand, and the
receptor?25Insulin makes another excellent expert example. Students
often know someone who is diabetic, so they may have a keen
interest in learning more about diabetes.
Secreting cells are the pancreatic beta cells. Target cells (in
this example) are muscle cells. The ligand is insulin. The receptor
is an integral protein in the membrane of the muscle
cell.25Endocrine SystemThe human endocrine system is composed of a
collection of glands that secrete a variety of hormones.
These chemicals use long distance communication to control the
daily functioning of the cells of the body, maintain homeostasis,
respond to environmental stimuli, and growth & development.
26The endocrine system is in contrast to the exocrine system,
which secretes its chemicals using ducts. The word endocrine
derives from the Greek words "endo" meaning inside, within, and
"crinis" for secrete. The endocrine system is an information signal
system like the nervous system, yet its effects and mechanism are
classifiably different. By contrast, the endocrine system's effects
are slow to initiate, and prolonged in their response, lasting from
a few hours up to weeks. 26Endocrine SystemThe endocrine system
produces more than 30 different chemicals used by your body to and
promote normal body function. This system contains 9 primary glands
as well as endocrine cells found within major organs. The endocrine
system is a ductless system that employs the circulatory system
when delivering chemical signals over long distances.
27The nervous system sends information very quickly, and
responses are generally short lived. Hormones are substances
(chemical mediators) released from endocrine tissue into the
bloodstream where they travel to target tissue and generate a
response. Hormones regulate various human functions, including
metabolism, growth and development, tissue function, sleep, and
mood. The field of study dealing with the endocrine system and its
disorders is endocrinology, a branch of internal medicine.
Features of endocrine glands are, in general, their ductless
nature, their vascularity, and usually the presence of
intracellular vacuoles or granules storing their hormones. In
contrast, exocrine glands, such as salivary glands, sweat glands,
and glands within the gastrointestinal tract, tend to be much less
vascular and have ducts or a hollow lumen (interior).
2728
While it is not necessary to memorize every cell type or gland
found within the system, it will be helpful to recognize the
endocrine glands and the function of the hormones produced by
select glands to use as examples of how both short and long
distance chemical communication occurs.
In addition to the specialized endocrine organs mentioned above,
many other organs that are part of other body systems, such as the
kidney, liver, heart and gonads, have secondary endocrine
functions. For example the kidney secretes endocrine hormones such
as erythropoietin and renin.28The Endocrine System works with the
Nervous SystemTwo systems coordinate communication throughout the
body: the endocrine system and the nervous system.The endocrine
system secretes hormones that communicate regulatory info
throughout body.The nervous system uses neurons to transmit
signals; these signals can regulate the release of hormones.29The
endocrine system is made of a series of glands that produce
chemicals called hormones. A number of glands that signal each
other in sequence are usually referred to as an axis, for example,
the hypothalamic-pituitary-adrenal axis.Table 45.1a
30Major Human Endocrine Glands and Some of Their Hormones. Have
students pick a favorite from either this slide or the next so they
can use it as an example in their free-response writing.Table
45.1b
31Major Human Endocrine Glands and Some of Their HormonesFigure
45.17
PathwayExampleStimulusColdSensory
neuronHypothalamusNeurosecretory cellReleasing hormoneBlood
vesselAnterior pituitaryTropic hormoneEndocrine
cellHormoneTargetcellsResponseNegative feedbackHypothalamus
secretesthyrotropin-releasinghormone (TRH).Anterior pituitary
secretesthyroid-stimulatinghormone (TSH, also knownas
thyrotropin).Thyroid gland secretesthyroid hormone(T3 and T4).Body
tissuesIncreased cellularmetabolism32How accurate were you?The
Process of Communication:Signal-Transduction PathwayThree stages of
the Signal-Transduction Pathway1. reception2. transduction3.
responseMost cell communication involves three basic steps,
reception, transduction and response. Today, we will see this
signal transduction pathway being initiated by hormones. We will
look at specific examples of how communication is completed using
this pathway.33Typical Signal Transduction Pathway
The diagram shows a typical signal transduction pathway. In our
example today, we will consider a ligand or signal molecule to be a
hormone produced by one of the endocrine glands we discussed
earlier.
The word transduce means to convert. A signal transduction
pathway converts the original signal molecule into a cellular
response. This conversion requires several intermediate messenger
molecules (sometimes called second messengers), so the signal is
actually converted or transduced several times, as shown in the
blue box above labeled Transduction. The concept of signal
transduction pathways will be seen over and over again in AP
Biology and is certain to be on the exam.
34Ligand = Chemical MessengerThree major classes of molecules
function as hormones in vertebrates (ligands)
Polypeptides (proteins and peptides)Amines derived from amino
acidsSteroid hormones
35The hormones we consider today fall into three main
categories. Polypeptides, amines and steroid hormones. The chemical
make up of each is different so it is not surprising that these
ligands impact cells very differently.35Cellular Response
PathwaysWater- and lipid-soluble hormones differ in their paths
through a bodyWater-soluble hormones are secreted by exocytosis,
travel freely in the bloodstream, and bind to cell-surface
receptorsLipid-soluble hormones diffuse across cell membranes,
travel in the bloodstream bound to transport proteins, and diffuse
through the membrane of target cells36Protein/peptide hormones are
released by exocytosis, steroid hormones are able to leave their
secretory cells by way of diffusion. Once in the blood stream, both
travel to their target cells.. Upon arrival at the target cell,
these two types of hormones have different methods of communicating
with the target cells.
Type of Receptor: Ex- G-protein linked(Water soluble =
polypeptides & amines, cant pass cell membrane)G protein linked
receptors are located in the membrane of the cell. When activated,
the G-protein linked receptor sets off a chain of events inside the
cell.37
Type of Receptor:Intracellular Receptor(Lipid Soluble = Steroid
Hormones, can pass cell membrane)
Some receptors are located inside the cell and are described as
intracellular receptors. The receptor for testosterone, for example
is found inside the cell.Testosterone is a steroid hormone.
Challenge students to explain why steroid hormones have
intracellular receptors, while protein hormones have extracellular
receptors. (Steroids are lipids and therefore easily diffuse
through the membrane and into the cell. Proteins will not diffuse
through the membrane due to both charge and size, so they must bind
with receptors on the cells surface.)38
Lipid-solublehormoneSECRETORYCELLWater-solublehormoneVIABLOODSignal
receptorTARGETCELLORCytoplasmicresponseGeneregulation(a)(b)CytoplasmicresponseGeneregulationSignalreceptorTransportproteinNUCLEUS39Receptor
location varies with hormone type.
Plasma
membraneEXTRACELLULARFLUIDCYTOPLASMReceptionTransductionResponseReceptorSignalingmoleculeActivationof
cellularresponseRelay molecules in a signal
transductionpathway321Recap40Overview of cell signaling.
Multiple Effects of HormonesThe same hormone may have different
effects on target cells that haveDifferent receptors for the
hormoneDifferent signal transduction pathways41The same hormone can
cause different reactions depending upon the cell it has
targeted.Multiple Effects of HormonesThe hormone epinephrine has
multiple effects in mediating the bodys response to short-term
stress
Epinephrine binds to receptors on the plasma membrane of liver
cells
This triggers the release of messenger molecules that activate
enzymes and result in the release of glucose into the
bloodstream42For example, epinephrine can be stimulatory is some
parts of the body and stimulatory in others.43
Epinephrine inhibits the glycogen synthesizing work of a liver
cell while promoting the breakdown of glycogen43
Different receptorsSame receptors but differentintracellular
proteins (not shown)Different cellularresponsesDifferent
cellularresponsesEpinephrineEpinephrineEpinephrine receptor
receptor
receptorGlycogendepositsVesseldilates.Vesselconstricts.Glycogenbreaks
downand glucoseis releasedfrom cell.(a) Liver cell(b)Skeletal
muscleblood vesselIntestinal bloodvessel(c)44One hormone, different
effects.Insulin and Glucagon: Control of Blood GlucoseHormones work
in pairs to maintain homeostasis.Insulin (decreases blood glucose)
and glucagon (increases blood glucose) are antagonistic hormones
that help maintain glucose homeostasis.
The pancreas has clusters of endocrine cells called pancreatic
islets with alpha cells that produce glucagon and beta cells that
produce insulin.45
Body cellstake up moreglucose.InsulinBeta cells
ofpancreasrelease insulininto the blood.Liver takesup glucose and
stores itas glycogen.Blood glucoselevel declines.Blood glucoselevel
rises.Homeostasis:Blood glucose level(70110 mg/100mL)STIMULUS:Blood
glucose level rises (for instance, after eating acarbohydrate-rich
meal).Liver breaksdown glycogenand releasesglucose intothe
blood.Alpha cells of pancreasrelease glucagon intothe
blood.GlucagonSTIMULUS:Blood glucose level falls (for instance,
afterskipping a meal).Figure 45.1346Describe the actions that occur
when blood glucose levels decline and when they rise. Glucagon and
insulin are paired hormones that work together to maintain blood
glucose levels between 70 and 110 mg/100mLOut of Balance: Diabetes
MellitusDiabetes mellitus is perhaps the best-known endocrine
disorder.
It is caused by a deficiency of insulin or a decreased response
to insulin in target tissues.
It is marked by elevated blood glucose levels.47Ask students to
explain how a lack of insulin leads to elevated levels of glucose
in the blood. Then ask them to suggest reasons this increased level
of glucose is harmful to the person with diabetes.Type 1 diabetes
mellitus (insulin-dependent) is an autoimmune disorder in which the
immune system destroys pancreatic beta cells.
Type 2 diabetes mellitus (non-insulin-dependent) involves
insulin deficiency or reduced response of target cells due to
change in insulin receptors.Out of Balance: Diabetes Mellitus48Type
1 has in the past been referred to as Juvenile Diabetes. Just as a
point of interest, the incidence varies from 8 to 17 per 100,000 in
Northern Europe and the U.S. with a high of about 35 per 100,000 in
Scandinavia to a low of 1 per 100,000 in Japan and China.Insulin
& Glucose Regulation
49Scroll across the bottom of the slide to activate the
animation controls and press PLAYPg. 150Diagram and label fig.
40.12 AND 40.15.Pg. 151Create a similar diagram for the stress
response. One loop will be short term stress and the other loop
will be long term stress.OutInsulin and glucagon are antagonistic
hormones. What does this mean? Use a specific example.