Topic 8 - Grey Matter Flashcards
What Is An Action Potential?
Large change in voltage across membrane, caused by changes in the permeability of the cell surface membrane
At What Point Is The Membrane at Resting Potential?
-70MV
What is Depolarisation?
When the inside of the axon is more positive and the outside is more negative
What is repolarisation?
Process of returning to the resting potential
What Happens During Depolarisation?
- change in potential difference causes Na+ channels to open
- Depolarisation increase and more Na+ channels are opened (positive feedback)
- Higher concentration of Na+ outside
- Potential difference reaches +40mv
What Happens During The Process of Repolarisation?
- Na+ channels close and Na+ permeability returns to low level
- K+ channels open due to depolarisation
- K+ moves down electrochemical gradient and outside becomes more negative as more K+ leaves
What Happens During The Process of Restoring Resting Potential?
- Membrane now highly permeable to K+ ions so more K+ leaves
- Hyperpolarisation occurs as the potential difference is more negative than usual
- Resting potential is restored by closing K+ channels
Why Is There A Potential Difference Across The Cell Surface Membrane?
- Sodium/potassium pump pumps Na+ out and K+ in, changing voltage difference
- Driven by energy from hydrolysis of ATP
- K+ diffuses our which causes a potential difference to pull it back into cell
Why Does More K+ Diffuse Out Of The Cell Than Na+?
Because the Membrane is permeable to K+ but not really Na+
What Are The Two Forces That Move K+?
- Concentration gradient creates by Na+ and K+ pump
- Electrical gradient causes by difference in charge from K+ diffusion
What Are the Two Divisions Of The Nervous System?
The central nervous system and the peripheral nervous system
What Is The Peripheral Nervous System Divided Into?
Autonomic and Somatic
What Is The Autonomic NS Divided Into?
Sympathetic and parasympathetic
What Is The Autonomic NS?
- Involuntary
- Stimulates smooth cardiac muscle/glands
What Is The Somatic NS?
- Voluntary
- Stimulates skeletal muscles
What Is The Order Of Neurones That The Cell Body Evolves Into?
Motor, sensory, relay
What Is The Order Of A Reflex Arc?
Stimulus, receptor, sensory, relay, motor, Response
What Does a Receptor Do?
Generate a nerve impulse
What Does A Sensory Neurone Do?
Pass nerve impulse to CNS down sensory pathway
What Does A Motor Neurone Do?
Carries impulse to effector
What Does A Relay Neurone Do?
Forms a synapse with the motor neurone and leaves down the spinal cord
What Are The Antagonistic Muscles In The Eye?
Radical and circular
What Happens When The Pupil Is Constricted?
The radial muscles relax and the circular muscles contract
What Happens When The Pupil Dilates?
Radical muscles contract and circular muscles relax
What Are Photoreceptors?
Cause nerve impulse to pass along optic nerve in the eye to the CNS
How Is Light Restricted When Entering The Eye?
Impulses are sent to circular muscles causing them to constrict the pupil
What Occurs In Impulse Transport Across A Synapse?
- Action potential depolarises membrane
- Depolarisation causes calcium channels to open/release calcium
- Calcium causes vesicles of neurotransmitter to fuse with presynaptic membrane and release it into synaptic cleft
- Neurotransmitter binds with receptors on postsynaptic membrane and cation channels open/release sodium
- Neurotransmitter releases and broken down/diffused
What Does Depolarisation Of A Synapse Do?
Allows an impulse to travel along cells
What Are The Two Types Of Summation?
Spatial and temporal
What Is Spatial Summation?
Impulses from different synapses
What Is Temporal Summation?
Several impulses from the same neurone
What Are Properties Of Nervous Control?
- Electrical
- Fast acting
- Short-term changes
- Carried by neurones
- Targets specific muscle/gland
What Are Properties Of Hormonal Control?
- Chemical
- Slow acting
- Long-term changes
- Carried by blood
- Widespread response (e.g growth)
What Was Discovered About Auxin?
Causes plants to grow towards the light as it’s in the tip. Moves down the shaded side of the plant causing curve. Can diffuse through agar
What Is The Frontal Lobe?
Responsible for decision making, planning, emotions etc.
What Is The Temporal Lobe?
Responsible for audio
What Is The Parietal Lobe?
Responsible for movement, sensation, calculation etc.
What Is The Occipital Lobe?
Responsible for vision
What Is The Thalamus?
Responsible for sensory information via white matter
What Is The Hypothalamus?
Responsible for temperature regulation and secretion it hormones
What Is The Hippocampus?
Responsible for long-term memory
What Is The Basal Ganglia?
Initiated movement
What Is A CT Scan?
- Narrow x-rays pass through tissue to show structure of brain.
- Detects disease
- Small parr’s not seen due to low quality
What Is A MRI Scan?
- Magnetic field and radio waves cause nucleis to line up with magnetic field
- Hydrogen line up due to high water content
- Radio waves interfere and spin round hydrogen to original position and release energy to create image
- Detects tumours due to 3D image
What Is A FMRI Scan?
- Strong magnets line up protons in blood
- Magnets turned off and on to pull protons back and forth to create image
- Oxygenated blood=active areas
- Deoxygenated blood= inactive areas
- Shows sequence of images
What Is A PET Scan?
- Radio tracers injected into blood
- Gamma rays emitted when positron collides with electron
- Picked up by detectors and increased blood flow shows more radio tracers
- Series of colour images
- Bright areas= more active
- Diagnose cancer spread, Alzheimer’s etc.
What Is Stereoscopic Vision?
Visual cortex compared vision from both eyes (close objects)
How Can We Tell That Objects Are Far Away?
Visual cues and past experiences
How Are Memories Stored?
- Pattern of connections
- Strength of synapse
How Do Snails Habituate?
- Gill withdraws due to stimulation of siphon
- Repeated stimulation stops gill withdrawing (habituation achieved)
During repeated stimulation, Ca channels release less Ca and neurotransmitter so no action potential
What Is Utilitarianism?
Right thing maximises happiness or pleasure
What Is The Human Genome Project?
Working out the order and location of bases that make up the human genome
What Were The Outcomes Of The Human Genome Project?
- Identified genes responsible for disease
- Personalised medicine
- Non-coding DNA can be important
- SNPs > When a single nucleotide is different in a DNA sequence
- Genetic variation makes drugs less effective
What Are The Problems Of The Human Genome Project?
- Tested positive for a gene can cause discrimination in insurance and employment even if you might not develop the condition
- Expensive
- Who should have this information?
