Exam 3 csv Flashcards
What are the functions of target cell receptor hormones?
Recognize and bind to particular hormone and Initiate a signal to intracellular effectors
Sensitivity of the target cell is relatred to what?
The number of receptors on the target cell
What does estrogen do during pregnancy related to receptors?
It stimulates the production of more oxytocin receptors
Priming up (Up regulation)
Increase the number of receptors on target cells
Desensitization ( Down Regulation)
Decrease the number of receptors on the target cells
Example of Desensitization
In non insulin dependent Diabetes it is thought that the number of insulin receptors is reduced.
Snergistic Hormonal Interactions
Two hormones work together to produce a result. Example Vitamin D and PTH
Additive Hormonal Interactions
Each hormone separately produces a response together they stimulate a greater response. Example Epi and NE work together in mass activation of the sympatheric NS
Complementary Hormonal Interactons
Each hormone stimulates different steps in the process. Example, In Spermatogenisis FSH and testosterone stimulate different steps in the process.
Permissive Hormonal Interactions Effects
Hormome enhances the responseivness of a target organ to a second hormone . Example during menstration the increase in of estrogen induces the formation of more receptors for progesterone
AntagonisticHormonal interaction Effects
Action of one hormone antagonizes the effects of another. Example Insulin and Glucagon
4 types of cellular surface messengers
G- Protein linked- Ion channel Receptors- Tyrosine Kinase Linked Receptors- Receptors with intrinsic enzyme activity
What are signal transduction mechanisms
Hormones that use a 2nd messenger system
Examples of hormones that use the G protein system
Chatecolomines such as Epi and NE
What happens when Epi or NE bind to a receptor
G protein dissociates ond one portion moves to activate the adenylate clyclase. This causes the breakdown of ATP into cAMP and 2 inorganic phosphates (Ppi). cAMP activates protein Kinase. Kinase phosphoralates (attaches) phosphate groups to different enzymes. This alters the metabolism of the cell.
Wha inactivates cAMP
Phosphodiesterase
Clinical example of cAMP activation.
Theopholin is used to raise cAMP levels in bronchial smoothe muscle. Thus dilates the bronchials.
Action of second messenger Phospholipase C
catalyzes the formation of IP3 and DAG
Sequence of events for Phospholipase C
- Hormone binds to the receptor 2. Activation of Phospholipase C 3. Formation of IP3 and DAG. 4 IP3 diffuses through the ctoplasm to the ER. 5. In the ER stimulation and release of Ca++ 6. Ca++ binds to calmodulin
Functions of calmodulin
Activates a number of kinase enzymes. Alters the metabolism of the cell Example. Ca++/ Calmoduiln complex in smooth muscles causes contraction
Function of DAG
Activates protein kinase C and activates or deactivates other proteins or enzymes
Example of DAG
Breakdown of glycogen into glucose in the river
Function of Tyrosine Kinase
Causes the cell to produce GLUT-4 and activation of MAP
GLUT-4
A transporter which allows glucose to enter the cell. Glucose can then be stored as glycogen or broken down into pyruvic acid and utilized in the Kreb’s cycle