Lecture_38_2014_noquizb

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April 30, 2014 – Chemical signals and hormones III
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No Pre-lecture quiz
Review of Hormone specificity
Hormone-mediated physiological tradeoffs
Stress responses
Introduction to sex hormones
Hormonal specificity: G-protein coupled receptors
Animation of g-protein coupled receptor example
http://highered.mcgrawhill.com/sites/0072507470/student_view0/chapter17/animation__membra
ne-bound_receptors__g_proteins__and_ca2__channels.html
Hormonal specificity: Tyrosine kinase receptors
Animation of tyrosine kinase receptors
• https://www.youtube.com/watch?v=apkY5c5
DjlM
Hormone-mediated Tradeoffs:
Interactions between stress, reproduction and immune function
Extraordinary ordinary Junco: http://juncoproject.org/videos/chapter-2/
Stress
Stress response
Operates via two interrelated systems:
• SAM (Sympathetic-adrenomedullary)
(Short Term Response)
• HPA (hypothalamic-pituitaryadrenocortical) (Chronic Response).
Adrenal Glands
Adrenal glands
• On top of the kidneys
• Two parts:
– Outer covering (cortex)
– Inner part (the medulla)
• Both parts secrete stress hormones
Adrenals
Short term response
SAM – short term stress response
• Adrenal medulla (the inner part) releases
epinephrine (adrenaline) and
norepinephrine
• Stimulates rapid mobilization of metabolic
resources: increased heart rate, BP, blood
glucose
• "Rapid response"
Some additional effects of the “fight or flight” response
1.) Redirection of blood flow from the skin and digestive system
toward heart, brain, and muscles.
2.) Relaxation pulmonary smooth muscle to dilate bronchi and
increase O2 uptake
Take home messages:
1.) Short term stress responses are EXTREMELY beneficial over
the short term.
2.) Prolonged stress responses can be harmful.
*Radio Lab episode on stress: http://www.radiolab.org/story/91580-stress/
Long term response
HPA axis and glucocorticoids
• Adrenal cortex produces glucocorticoid
hormones (GC).
• Cortisol is most important human (GC),
involved in regulating metabolism, immune
response, and general homeostasis.
• Elevated cortisol leads to:
– Short term metabolism of fat stores into
glucose
– Increased hunger
– Suppression of immune response;
– Cardiovascular changes (e.g. increases in
BP)
HPA axis and the stress response
• Hypothalmus secretes CRH, which:
– causes the pituitary to secrete ACTH,
– which stimulates the adrenal medulla to
release epinephrine and norepinephrine
– and the adrenal cortex to release GC.
Feedback inhibition by cortisol on ACTH
Hypothalamus
Pituitary gland
Adrenal
gland
Results of injecting ACTH into human volunteers
This graph shows the . . .
a. Positive influence ACTH has on cortisol release
b. Inhibitory feedback of cortisol on ACTH release
Results of injecting cortisol into human volunteers
This graph shows the . . .
a. Positive influence ACTH has on cortisol release
b. Inhibitory feedback of cortisol on ACTH release
Figure 47-15
Stressed
individual
Unstressed
individual
Hormone-mediated Tradeoffs
Interactions between stress, reproduction and immune function

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