Which form of cell-to-cell communication uses the direct transfer of electrical and chemical signals?
Gap Junction Signaling
Neurotransmitters and neurohormones both
are released by neurons and affect only cells with specific receptors.
The most significant difference between a paracrine and an autocrine is
the cell that responds to it
Autocrine signals
are produced by and act upon the same cell.
An ion widely important in intracellular signaling is
calcium
Signal molecule receptors exhibit
1. specificity
2. competition
3. saturation
The most rapid intracellular responses to signals result from activation of receptors that are also ________
ion channels
The binding of lipophilic messengers, such as steroid hormones, to their receptors triggers
gene transcription
An integrating center
evaluates incoming signals and compares it with the setpoint.
What stabilizes the variable being regulated?
Negative feedback
The increasingly forceful uterine contractions that lead to childbirth are an example of
positive feedback
Compared to endocrine reflexes, neural reflexes __________.
respond rapidly but are very brief
Receptor molecules are located
1. in the nucleus
2. in the outer cell membrane
3. in the cytosol
Each of the following is an example of homeostasis except one. Identify the exception.
A decrease in body temperature triggers a neural response that initiates physiological changes to increase body temperature.
A rise in estrogen during the menstrual cyc
B
Which type of feedback promotes homeostasis?
negative
Choose the correct example of signal amplification.
A chemical signal is converted into a mechanical signal.
One hormone molecule causes the activation of more than one second messenger molecule.
One hormone-producing cell alters the activity of more than
B
In a simple endocrine reflex, the endocrine cell is the
1. sensor
2. integrating center
5 Types of local communication
paracrine
autocrine
cytokines
junctions
contact-dependent
Long Distance Comm
1. Chemical (Hormones, neurohormones, neurotransmitters)
2. Electrical
Gap Junctions
proteins that create direct cytoplasmic connections between adjacent cells so the cells can act like one giant cell
Autocrine
acts on their self by simple diffusion
Paracrine
Diffuse to adjacent cells by simple diffusion
classic" hormones
secreted in minute concentrations to bloodstream to reach receptor on target tissue
long distance comm
made in advance and stored until needed
Neurotransmitters
rapid acting neurocrine molecules
neuromodulators
slow acting autocrine / paracrine
neurohormones
secrete into bloodstream in minute concentrations
cytokines
local
made on demand and immediately released
lipophilic
simple diffusion --> alters gene activity by binding to intercellular target
lipophobic
signal transduction signaling--> cannot cross membrane
4 receptor types
receptor channel
receptor enzyme
G-P-C receptor
Integrin
Receptor channels
ion transport
Receptor enzymes
tyrosine kinase receptor enzymes
G-P-C- receptors
transmembrane activation of G-protein
integrin
structural cell protein linked to cytoskeleton and into ECF which alters cytoskeleton to act
Kinase
transfers phosphate
Phosphatase
catalyzes addition of phosphate
Phosphorylase
removes phosphate
Control patters
tonic control
antagonistic control
tonic control
always on--> chronic control. similar to the volume dial on a radio
regulates physiological parameters in an up/down fashion
anatagonistic control
one signal increases and the second signal decreases
cannon's postulate
one signal can have different effects in different tissues
afferent
signal--> integrating center
efferent
integrating center--> response