C6 LUKE Flashcards
(26 cards)
Depolarisation
Stimulus has triggered enough Na+ VGCs to open and the inside of the neuron now has a membrane potential of +30 mV.
The change in voltage is enough for the next Na+ VGCs to open, changing voltage in that section and so on.
Repolarisation
The neuron has now sent the signal down the axon and needs to return to resting value of -70 mV.
The Na+ VGCs become deactivated. The K+ VGCs open and K+ rushes out of the cell. This causes membrane potential to decrease, past the resting value, to -85 mV. This is hyperpolarisation.
There is a pump that transports 3 Na+ out of cell and 2 K+ back into cell to restore neuron to -70 mV.
Action Potential
Is a brief reversal of the potential inside a portion of the neuron compared to the outside.
Is needed for electrical charge to be transmitted from one neuron to another.
A stimulus needs to cause depolarisation for AP to occur.
Communication Between Neurons
Action potential reaches axon terminal and change in voltage leads to opening of Ca2+ VGCs.
Presence of Ca2+ ions causes vesicle with neurotransmitter to fuse with membrane and release neurotransmitter into synaptic cleft.
Once neurotransmitter crosses synaptic cleft, it attaches to receptor on ligand gated channel.
Depending if neurotransmitter is excitatory or inhibitory, AP will continue in next neuron.
Nervous System Is
The network of neurons that carry signals and messages to and from the brain and spinal cord to different parts of the body.
Endocrine System Is
The collection of glands that produce hormones that regulate bodily functions,
eg. Metabolism, growth and development, sexual function, sleep and mood.
Two Different Parts Of Peripheral Nervous System
Sympathetic V Parasympathetic
Para:
Rest, digest
Lowered HR and breathing
Increased digestion
Symp:
Fight, flight, freeze
Heightened HR and breathing and blood flow
Decreased digestion
Divisions Of Nervous System
Central and Peripheral
CNS
Brain and spinal cord
PNS
Peripheral nerves
Sensory and motor neurons
Similarities + Differences Between NS + ES
Sim:
Both send chemical signals (hormones and neurotransmitter)
Diff:
NS uses electrical signals and is much faster acting.
NS has instant responses. ES has slower, longer lasting effects.
NS uses nerves to transmit information, ES uses bloodstream.
Homeostasis Is
The maintenance of constant internal conditions despite changes in external and internal environment.
Broad
3 Components Of NS
Receptor - senses change in environment
Control centre- determines how to respond to change
Effector - receives signals and adjusts accordingly.
What Is A Neurotransmitter
Two Types?
A chemical messenger that allows neurons to communicate with each other
Excitatory:
The ligand channel opens and Na+ flows in and AP occurs.
Inhibitory:
It prevents the flow of Na+
What Is A Hormone?
A chemical messenger that is released by endocrine glands and travels around the body in the bloodstream.
Role Of Parts Of A Neuron
Cell body- keeps cell alive and contains nucleus
Dendrites- collects information and sends it to cell body
Axon- transmits information away from cell body to other neurons, muscles or glands.
Myelin- fatty tissue insulates Axon and allows for faster transmission of electrical signals
Schwann cells- produce myelin sheath
Nodes of Ranvier- gaps in myelin sheath that contain VGCs
Link Between Stimulus + Action Potential
Stimulus Arrives:
Stimulus causes ligand channels in the neurons membrane to open and Na+ rush in
If enough Na+ enters and voltage reaches -55mV, the threshold is reached.
This causes AP to start
Parts Needed For Negative Feedback Question
Stimulus, receptors, neurons/hormones, control centre, effectors, response
4 Steps In Propogation Of Action Potential
Stimulus
Depolarisation
Repolarisation
Hyperpolarisation
Resting Potential
The membrane potential when a neuron is not firing.
Resting potential value is -70 mV.
Membrane Potential
The difference in electrical potential between the interior and exterior of a cell.
What Is Negative Feedback
A factor that affects the body’s internal conditions that deviates it from optimum.
The model that brings the conditions back to optimum.
Important Glands
Hypothalamus:
Control centre of ES
Releases hormones that control function of pituitary gland.
Pituitary Gland:
Known as master gland
Produces many hormones and controls function of other endocrine glands.
Types of Neurons
Sensory Neurons:
Receive stimulus and send messages to control centre.
Motor Neurons:
Receive info from control centre and transmits signals to muscles and glands.
Interneurons
Types of Receptors
Electromagnetic:
Thermoreceptors- detect temperature
Photoreceptors- detect light and colour
Mechanoreceptors:
Touch, hearing, balance, pressure
Chemoreceptors:
Taste - nose and tongue
Nocireceptors:
Pain - skin, muscles, joints and bones
Thermoregulation - Too Hot
The body dissipates heat by:
- Sending neural impulse to sweat glands to increase sweat and therefore increased heat loss
- Vasodilation leads to increased blood flow near skin and heat loss due to radiation.
- Pilorelaxation leads to no heat trapping
- Adrenal glands and hypothalamus decrease release of hormones leading to reduced metabolic rate
Behavioural changes: reduced movements, less clothing, open body position, reduce appetite
