Chapter 3: Control Mechanisms and Signalling Flashcards
3 main control mechanisms for cell communications
1) enzymes
2) direct communications
3) indirect communication via chemical messaging
3 main methods of direct communication between cells
1) gap junctions: small tunnels that bridge the cytoplasm of neighboring cells and allows the passage of small ions and molecules. also allows for the depolarization of adjacent cells, PERMITTING ELECTRICAL SIGNALS.
2) transient linkages: cells line up on surface markers to temporarily communicate (ex/ antibody/antigen linkaes in the immune system
3) nano tubules: long tubes with internal actin filament support. can transfer larger molecules and organelles, and found in developing cells and immune cells.
what chemicals cause gap junctions to close?
gap junctions rapidly close in response to an increase in calcium or H+
gap junction tunnels are made of ___ protein
connexin protein
The main difference in what gap junctions and nanotubules transfer between cells?
gap junctions can transfer small ions, but nanotubules allow for the transfer of larger molecules and ORGANELLES.
in what cells would you find nanotubules
in developing cells and immune cells
which type of structural protein would you find with nanotubueles?
microfilament actin
when two cells communicate via indirect chemical messaging, the receptor is typically made of ___
transmembrane glycoprotein
what is a paracrine chemical and give an example
paracrine chemical: LOCAL chemical messngers produced by a specific cell whose effect is exerted on NEIGHBORING cells for a particular response (ex/ histamine is released by skin cells and trigger vessel dilation around it)
what is an autocrine chemical
autocrine chemical: when a cell secretes local messenger and the messenger also affects the cell it was secreted from.
_____ are used by neurons which communnicate with the cells they innervate. Are these short or long range?
neurotransmitters. they are short range
unlike neurotransmitters, ____ are very long range chemical messengers that are secreted by the endocrine system and is carried by the ____ ____ to exert change on distant organs.
HORMONES are very long range chemical messengers that are secreted by the endocrine system and is carried by the CIRCULATORY FLUID (blood or lymph) to exert change on distant organs.
what is a neurohormone?
hormones released by the neurocirculatory neurons: respond to electrical signals like normal neurons, but rather than releasing NTs to innervated cell, they release neurohormones into the BLOOD or LYMPH.
example of a neurohormone
just like normal hormones, neurohormones are secreted into the blood or lymph, and are able to target long range targets. an example is ADH.
the hypothalamus has neurosecretory neurons that produce ADH and store them in the pituitary gland. when electrically excited, the neurohormone ADH is released into the hypophyseal circulatory (BLOOD) system.
a ____ is typically made in a gland and is released into the environment rather than the extracellular system.
pheromone
what is a cytokine
a regulatory peptide with variety of effects. they are not produced by glands, rather thay are made by all body cell types
what gland makes cytokines for regulation?
all cells make different types of cytokines.
6 ways a cell can undergo indirect chemical messaging communication
1) neurotransmitter (short distance)
2) neurohormone (long distance)
3) hormone (long distance)
4) cytokine (long and short distance)
5) pheromone (environmental)
6) Paracrine or autcrine signalling (local/short distance)
primary purine that is used as a signalling molecuel
ATP. often used as a paracine and neurotransmitter
common structures of signalling molecules
1) eicosanoids
2) inorganic gases
3) purines
4) amines
5) peptides
6) steroids
7) reinoids (vitamin A derivatives)
_____ of receptors cause target cells to be less responsive, and is dependent on _____
DOWNREGULATION of receptors cause target cells to be less responsive, and is dependent on ACCLIMATIZATION
usually, hormones delivered by the blood or neurotransmitters released from nerve endings usually do not trigger changes in target cells directly, rather, cell responses are conveyed via ____ ____
signal transduction
signal transduction
incoming signals from an extracellular chemical messenger are conveyed to the INTERIOR of a target cell for execution.
extracellular messenger interacts with a receptor on the target cell, and triggers a sequence of ___ ___ that control homeostatic maintenance
INTRAcellular events. (the messengers rarely actually enter the target cell, except for hormones)
