Seyfried Flashcards
Roles of WNT signaling
carcinogenesis and embryonic development (body axis patterning, cell fate
specification, cell proliferation and cell migration).
tissue regeneration
Angiogenesis
physiological process through which new blood vessels form from preexisting vessels
Somitogenesis
process by which somites form. Somites are bilaterally paired blocks of paraxial mesoderm that form along the anterior-posterior axis of the embryo.
Hormone
chemical substance produced in the body that
controls and regulates the activity of certain cells or
organs.
secreted by special endocrine glands and circulate within the circulation or body fluid
active in small concentration: 10^-9 - 10^-12 M
Autocrine signaling
Secreted substance affects the secreting cell:
Example: Noradrenaline (NA) (inhibits further release)
The gaseous hormone Nitric oxide (NO)
parakrin signalling
effect blood pressure
Synthase from L Arginine
adern enger –> pressure höher via EDRF
Control hormones
(= glandotrope hormones)
- Only produced in the hypothalamus and the pituitary gland (frontal lobe)
- Control the activity of other hormone glands
Effector hormones
- Control activity of target organs
- Feedback effects on control-hormone producing
endocrine glands
Islands of Langerhans/Pancreas
Cell types in the Islands of Langerhans:
alpha (= A)-cells: Glucagon (mostly peripheral, approx. 20%)
beta (= B)-cells: Insulin (mostly internal, approx. 75%)
D-cells: Somatostatin (paracrine effect, inhibits
secretion of insulin and glucagon; buffers large fluctuations of blood sugar levels)
Signal transduction mechanisms effects
direct: gene activation on the nucleus
indirect:
Binding of the hormone (first messenger) to a membrane receptor
Synthesis of an intra-cellular second messenger
second messenger induces a physiological hormone effect
usually rapid, short term responses
Unit for pressure
1 mmHg = 1 Torr
colloid osmotic pressure:
osmotic pressure due to disolved proteins
