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Things Like This Don't Just Happen.
Coordination is Required!
Any Questions?
Compare the uses of cell signaling in different lineages of organisms.
Identify common features in all cell signaling mechanisms.
Compare different modes of cell signaling in animal systems
Diagram the processes by which signal transduction occurs in multicellular animals, including steroid and lipid hormone signaling pathways
Diagram the regulatory effects of various hormones in animals and plants, at the cellular and system-wide levels of organization.
Why is communication between cells necessary?
How is cellular communication used in multicellular life?
How do mechanisms of cellular communication demonstrate a shared evolutionary history among organisms?
How Cells Communicate
Molecules are Required!
The 3 Phases of Signal Reception
Why Cells Communicate (Multicellular Version)
This is a review of "Cellular Communication"
The Immune System demonstrates Local Signaling
"ligands"
Three major hormones are responsible for the total breakdown and reorganization of juvenile arthropods into adult forms (and its ensuing awesomeness).
Released by cells, received by neighbors
An Epinephrine ("Adrenaline") Receptor
What kind of hormone is epinephrine?
Epinephrine is a polar amine ligand
Epinephrine signal transduction is mediated by G-Protein linked receptors.
G-Proteins are very common signal relay proteins for membrane receptor ligands.
"G-Protein" means it is associated with GTP
AMP is high when ATP is low
Pheromones!
Nervous Systems (Not Now!)
Lipid Hormones Tend To Have Longer Term Effects than Peptides
Signaling Molecules produced by one organism that are recieved by another organism
Generally speaking, nervous and endocrine systems have complementary purposes.
Nervous system: quick, fast, regulation. More on that later.
Endocrine system: long term, regular regulation.
Both systems interact
Estrogen is responsible for long term changes in sexual cycles (menstruation, puberty).
Estrogen activates long term responses by changing protein expression in cells.
{Vitellogenin is a precursor to nutritive egg yolk proteins present in all egg producing female animals}
Cells Amplify A Message
The ligand isn't important.
The Response is!
The Role of the "Second Messenger"
Internal signalling molecules released due to external ("first") signals
Things Get Complicated Quickly
Have Hormones, Too!
The Endocrine System
Auxin Production at the Apical Bud determines the direction of plant growth
Endocrine glands respond from nervous system cues, or from hormones made by other endocrine glands.
The Brain is the ultimate seat of control of endocrine and nervous systems
Abscision (loss of leaves),
involves interactions between many hormones, including ethylene, gibberelin, and absisic acid
An example of negative feedback
An example of positive feedback
A typical neuroendocrine signaling pathway
The pituitary gland is typically referred to as the "master gland"
It makes control hormones for many other glands throughout the body.
Input from the hypothalamus is crucial.
The pituitary has two distinct lobes that make distinct hormones.
All pituitary hormones are peptidyl.
The thyroid makes two hormones (T3 and T4) which are involved in regulating metabolism.
Iodine is necessary for proper thyroid function
The parathyroids produce parathyroid hormone (PTH), which is involved in regulating calcium levels in the blood.
Calcium is an important second messenger in many cellular processes.
A "goiter" due to insufficient iodine in the diet
Gibberellin treatment leads to "bolting" in growing plants & accelerated fruit ripening
Intake of water in germinating seeds leads to gibberelin production and the breakdown of stored starch to power cotyledon growth
The Adrenal glands are involved in producing stress hormones:
Increased ethylene is associated with the "triple response" in young plants, a reaction to encountering an overhead blockage during growth
Decreasing [ABA] leads to germination
Ethylene is a gas!
It triggers growth
& Fruit Ripening
The regulation of the menstrual cycle is the responsibility of four major hormones
Ethylene response mutants
Pituitary Hormones:
Trigger development and release of a mature ovum (inside a follicle).
Ovarian Hormones:
Are involved in the development and maintenance of the uterine lining (the endometrium)
This is a very important thing that you need to understand.
A bunch of very cool feedback loops.
The human menstural cycle is 28 days, EXACTLY & ALWAYS!!!
:)
The gonads (ovaries and testes) produce the sex hormones which control:
Leads To
We're not going to spend a lot of time here.
Note: Same hormones involved here as in female gamete production, with ONE major difference.