Final Flashcards
(216 cards)
What is homeostatis
maintence of relatively constant conditions in the internal environment
what is negative feedback control in homeostatiss
- Negative because the response of the system is opposite in direction to the change that set in motion
Deviation away from its set point
describe steps negative feeback loop
- Sensors (input) > integrating centre (set of neural circuits in the brain or an endocrine gland) > compares regulated variable to set point > orchestrates response > output to the cells, tissues and organs
what is positive feedback control
- Same direction as the change that sets it in motion
e.g. of a tissu with gap juncitons?
cardiac
benefits of gap junctions
adjacent cells formed by connexins - connexon form channels that allow ions and small mocluels to pass direclty from one cell to another
juxtacrine communication?
direct contact btw cells - gap junctions
paracrine cellular communication?
short distance, immediate cellular environment, local coordiantin
autocrine cellular communication?
cell signals to self, self stimulation or self identitiy
endocrine cellular communication?
to distant sites, via hormones in the blood stream
what is an agonsit
ligands that binds to receptors and produces a biological response
e.g. of an agonist
E.G. morphine - opioid agonist used in the treatment of pain. Binds to mu opioid receptors in the spinal cord and brain and blocking pain signals from reaching consciousness. We have mu opioid receptors which prevent us from feeling pain under certain circumstances e.g. stress
what is an antagonist?
ligands that bind to receptors but do not produce a response - instead - they may compete with agonists for the receptor, decreasing the likelihood that the binding of agonist to receptor will occur and bring about a response
e.g. antagonist
E.g. naloxone - antagonist - binds to my opioid receptor 10x the strength of morphine - prevents morphine from binding there, reversing the effects of morphine
role of immune sstem
prevent infections and eradicate already estbalished infections
what does immunity refer to
bodys ability to recognise and eliminate microorgansims
what is innate immunity
intial protection agaisnt infection - blocks entry of microbes and eliminates those that do enter
what is adaptive immunity
specialised defence against infection
what are the phsyical and chemiCAL BARRIERS (immunity)
skin, respiratory system, stomach
how does the skin act as a barrier
sebaceous glands secrete sebum to inhibit bacterial growth
how does the respiratory system act as a barrier ( immunity)
mucus production which traps fogein particles that are inhaled
how does the stomach act as a barrier ( immunity)
HCI to kill ingested pathogens
what are the types of lymphoid cells
○ Natural killer cells - cells with abundant cytoplasmic granules, nonspecific defence against microorganisms
Lymphocytes - small cell with a large nucleus and very little cytoplasm, specific defence against a particular microorganism
cells in bone marrow
b cells