1 Flashcards
Define “cell signalling”
The process in which one cell tells another cell to do something
Define “Endocrine Signalling”
Signals that are released by specialized cells and released into the bloodstream and carried to target cells in distant parts of the body
Define “Paracrine Signalling”
Cells that are near one another communicate through the release of chemical messengers
Define “Neuronal Signalling”
Nerve cells transmit signals between the synapse, between two nerve cells where signal transmission occurs
Define “Contact Dependant Signalling”
2 cells bind to one another due to their complementary proteins on their surfaces. When the proteins bind to one another, this causes a conformation change, transmitting a signal
Describe the possible outcomes of a signal
Migration Survival Division Differentiation Apoptosis
Describe the role of a morphogen
A molecule that defines two or more cell fates at different concentrations (french flag model)
Describe the relay system
A signal is sent, which alters the target cells genes, therefore triggering another signal onto the next cell
Name the 5 key developmental signalling pathways
Hedgehog pathway Notch pathway Wnt pathway TGFB pathway FGF pathway
Name the 2 parts of a developing gastrula
Hensen’s node
Primitive streak
Describe the sections of a blastocyst
The outer layer of a blastocyst consists of cells collectively called the trophoblast. Which gives rise to the placenta. Within the trophoblast there is an inner cell mass (ICM) which subsequently forms the embryo.
Why is gastilation so important
Gastilation forms 3 germ layers, which then forms the tissues required for embryo formation
What is a nervous system?
A system that allows us to respond to a stimulus
Order:Assessment of the stimulus, Preparation of the response, Communication to responding structures
how does The Hippocampal Trisynaptic Circuit work
A signal travels from the entorhinal cortex in layer 2 to the “dentate gyrus”(granule cells) via the perforant pathway, the signal then travels to “CA3” (pyramidal cells) via the mossy fibres, the signal then travels to “CA1” (pyramidal cells) via the chaffer collaterals, and the signal finally ends up at the entorhinal cortex in layer 5
what does the Hippocampal Trisynaptic Circuit do
it changes the signal that is passed through, and is “tasted” by 1000s of neurons. The hippocampus and cortex play a role in learning, forming memories and retrieving them
Explain neural plasticity
The ability of the brain or neuron to adjust in response to a new situation or environment
Where does the PNS transmit information
The PNS transmits information to and from the CNS and regulates movement and the internal environment
What are the PNS two efferent components
the motor system and the autonomic nervous system
What does the sympathetic division do
regulates arousal and energy generation (“fight-or-flight” response)
What does the parasympathetic division do
has antagonistic effects on target organs and promotes calming and a return to “rest and digest” functions
What does the enteric division do
controls activity of the digestive tract, pancreas, and gallbladder
What are the 2 types of matter the brain and spinal cord contain and what is the difference between them?
Gray matter:which consists of neuron cell bodies, dendrites, and unmyelinated axons
White matter:which consists of bundles of myelinated axons
What does an axon hillock do?
The place in a neuron where the action potential is reached
What cells are located in the nervous system?
Nerve cells (neurons) Glial cells (glia)
What are the 4 main regions of a neuron
Cell body
Dendrites
Axons (one or more)
Axon terminals
Do all cells create an action potential?
no, some just relay information
What are the 3 main neurons and their functions
Afferent : carry sensory information into the NS
Efferent: carry commands to physiological and behaviourial effectors
Interneurons : integrate and store information and communicate between afferent and efferent neurons
Explain the 3 processes in which the membrane potential can change
depolarisation(decrease in potential)
repolarisation(return to resting potential after depolarisation)
hyperpolarisation(increase in potential)
Explain the process in which a signal crosses a synapse
An action potential causes depolarisation of the membrane potential, this depolarisation then causes Ca2+ channels to open. The Ca2+ then molecularly changes the neurotransmitter vesicles which then bind to the membrane at the synapse and releases the neurotransmitters
Which neurotransmitters brings about hyperpolarisation
Inhibitory neurotransmitters (negative) due to cl- entry and k+ exit
Which neurotransmitters brings about depolarisation
Stimulatory neurotransmitters (positive)
What the the membrane resting potential
-70mv
How do sensory cells convert stimuli into APs?
Physical and chemical stimuli are converted to neural signals by sensory receptor cells, these are then transmitted to the CNS for processing and interpretation
Explain how the stretching of muscle can create an AP?
The stretching of a muscle causes an ion channel to open. This results in the depolarisation of the membrane creating a receptor potential, this then spreads onto the axon hillock which stimulates an AP
How are different sensations perceived?
The APs from different kinds of sensory cells arrive at different places in the CNS.
What determines the intensity of the sensation?
The frequency of AP
What do mechanoreceptors respond to, and where are they found?
Mechanical forces (skin sensations, sensing BP, hearing and maintenance of balance) Found in muscles, tendons and ligaments
What do compound eyes consist of?
ommatidia (optical unit) - the number of ommatidia varies
An ommatidium consists of a ; corneal lens, crystalline cone, pigment cell, and a photoreceptor
