14 Flashcards
Neurotransmitters?
diffuses across synapses
Hormones and neurohormones?
Travels through long distances by the blood stream.
Neurohormones: produced by tissues
Hormones: produced by endocrine glands
Distances of continuum of cellular communication systems? 5*
Cytoplasmic contact -> recognition molecules on adjacent cells -> local diffusion -> transport in blood -> outside environment
Neurotransmitter?
when a signal travels through a synapse via paracrine communication.
Paracrine communication?
when one cell releases a signaling molecule and another cell’s receptor obtain that signal through diffusion.
Endocrine system?
cells within specialized endocrine glands that release chemicals called hormones through the blood. It binds to a receptor on the target cells and causes various effects.
When the signal gets in contact with a receptor, it changes the conformation of the receptor.
Nervous system?
long distance transport (by the cell being long) of electrical signals within cells and short distance (paracrine) signaling between cells at the synapse through diffusion.
How signals travel through the entire nervous system?
*Sensory receptors: mechanoreceptors, photoreceptors
Then through afferent neuron
*integrating center: brain, ganglia
Then through efferent neuron
*effector organs (output pathways): muscles, glands
Three main types of neurons and similarities 4*?
*Sensory neuron
*Interneuron
*Motor neuron
•They all have a cell body, processes (some of them called dendrites), and axon.
!!!Differences between the structures of the neurons?
How does the structure of the neuron work in coordination?
Dendrites receive incoming information, and axons generally communicate electrical signals out from the cell, often across long distances.
Parts of the neuron? 4*
Dendrites -> cell body > axon -> axon terminal and synapse
Glial cells?
specialized cells that support and maintain neurons.
Graded potential?
*Occur in dendrites and cell body
*Only travel short distances
*Vary in magnitude
Action potentials?
*Occur in axons
*All or on
*Can be “regenerated” so can be conducted across long distances
Synaptic potential?
it cause neurotransmitter release.
!!!Neurons work together
sensory receptors get that signal, and then pass it to afferent neurons that conduct the signal towards the integrating centor. The interneuron
!!!What is an electrical signal in a neuron?
a change in the electrical gradient across the cell membrane, called the membrane potential. A typical neuron maintains a membrane potential of -70, thus slightly more negative in the inside. An increase in membrane potential is called depolarization, while a decrease is called hyperpolarization.
*Granded potential: occur in dendrites in cell body and travel short distances and vary in magnitude.
*action potentials: occur in axons that when an action potential is triggered, its always the same magnitude and duration within the cell.
*Synaptic potential that cause neurotransmitter release.
Sensory receptors?
all types of sensory receptors transducer incoming signals that changes the membrane potential (electrical gradient across the cell membrane).
Three types of sensory receptors?
•Chemoreceptor: Receptor protein gets a chemical stimulus, which signal a transduction pathway. It activates an ion channel, and change in membrane potential, which then signal to integrating center.
•Mechanoreceptor: Receptor protein gets a pressure stimulus due to a change in pressure, which activates an ion channel, and change in e membrane potential, which then signal to integrating center.
•Photoreceptor: receptor protein gets a light stimulus, which signal a transduction pathway. It activates an ion channel, and change in membrane potential, which then signal it integrating center.
Signaling in a neural circuit?
*sensory neuron detects a signal and generates a type of graded potential called a receptor potential.
*graded potential triggers action potentials that are conducted towards the central nervous system.
*Action potentials trigger the release of neurotransmitter onto the interneuron.
*Binding of that interneuron into the receptor generates a graded potential in the cell body of the interneuron.
*That graded potential in the interneuron e trigger action potentials in the axon of the interneuron.
*action potentials trigger release of neurotransmitter onto the efferent neuron.
*Efferent neurons generate a graded potential which triggers action potentials, which ultimately Results in release of neurotransmitter onto the effector, causing a response.
How do receptors determine intensity of signals?
Gentle pressure: modest change of receptor protein, which causes a modest change in opening and closing in ion channel, which cause a small rate of potential, and lower frequency of action potential.
Higher pressure: large rate of potential, and higher frequency of action potential
Acute stress?
Sudden fight or flight stress.
Stress response is coordinated how?
Coordinated by both the nervous system and the endocrine system working together
Steps to processing the signal? 4*
Sensory receptors in which receptor cells detect signal -> send signal to central nervous system -> brain processes the signals -> activates sympathetic nervous system and/or the HPA axis.
Where in the brain does the decision process of the signal occur?
in the hypothalamus.
the two related pathways between sympathetic or parasympathetic nervous systems? 2*
- Two neuron chain that directly releases neurotransmitter onto target organ as norepinephrine.
- One neuron chain in which neurotransmitter stimulate pathway via adrenal medulla (sympathetic) which releases epinephrine and norepinephrine into the blood by the endocrine system to the target organ.
Why does the effect of the adrenal medulla take a long time?
Because epinephrine travels through the blood stream.
Endocrine system from signals from hypothalamus as hypothalamic-pituitary axis?
Signals from hypothalamus in the form of CRF goes through the blood to the anterior pituitary. Then, ACTH in the blood travels to the adrenal cortex. Cortisol in blood goes to target organs.
Cortisol action?
Cortisol signal (being a steroid that is lipid composed and soluble) binds to an intracellular receptor which is translocated to the nucleus. It then binds to DNA and acts as a transcription factor, which changes the synthesis of mRNA.
Why is hypothalamic-pituitary axis slower than the sympathetic nervous system?
Because more steps have to go through the blood stream.
Why is Hypothalamic-pituitary axis important?
cortisol is helpful for recovery because it takes a long time for an action to occur after a response.
Acute stress?
response (fight or flight), short-term stressors
Chronic stress?
Long term that cause some negative effects:
*memory loss, lack of concentration
*Immune suppression
*Weight gain/weight loss
*Osteoporosis, irritable bowel syndrome, etc
How does chronic stress really works?
neurons in the cortex and hippocampus get smaller (for thinking), while neurons in the amygdala get larger (responsible for fear)
Autocrine?
When a cell releases a signaling molecule which gets detected by a receptor of the same cell.
Juxtacrine?
Communications in which the cells are touching.
