Coordination Flashcards
Describe how neurotransmitters are transported across the synapse
Action potential arrives at synaptic knob Calcium channels open Calcium enters Neurotransmitter vestiges migrate to pre-synaptic membrane Neurotransmitter diffuses across cleft It attached to specific receptors Causes sodium channels to open Sodium enters Post-synapse depolarised New action potential created there Neurotransmitter broken by enzyme in cleft then resynthasised using ATP Sodium channels close
What is a cholinergic synapse
When the neurotransmitter is chemical called acetylcholine
What happens in synapse if inhibitory used
Chloride channels open
Chloride ions diffuse in
Post synapse more negative than resting potential
Hyperpolarisation
Makes it less likely that an action potential will be created
What is spatial summation
Multiple neurones combine
In order to release enough neurotransmitter to exceed threshold
Thus creating action potential
What is temporal summation
Single neurone
Releases neurotransmitter many times in short period
If total amount exceeds threshold
New action potential triggered
What is GABA
A neurotransmitter that inhibits the production of action potentials
What are the two types of eye receptors and where are they found
Rod cells
Cone cells
In retina
What is meant by saying rod and cone cells are transducers
They convert light energy into electrical energy of nerve impulses
What pigment is in rod cells and what does it detect
Rhodopsin
Detects light
What is a bipolar neurone
Sensory neurone
Where generator potential is created
What type of light does rod cells detect and why
Dim light
As really sensitive to light
So less light required for stimulation
What happens when light hits rod cells
Their shape changes as protein breaks down
The cells pool resources from the stimulus to cause action potential (greater chance of reaching threshold together) - spatial summation
Why can’t rod cells distinguish between different light sources
They have low visual acuity
Why do rod cells produce black and white images
They can’t distinguish between separate sources of light that stimulate them
Why are there different types of cone cells
So they can respond to different wavelengths of light
How many different types of cone cells are there
3
Why do cone cells require more light than rod cells
Different pigment
Needs higher light intensity to create a generator potential
Why do cone cells have good visual acuity
The brain receives separate impulses from stimulated cells
So able to distinguish between separate light sources
Why is there an unequal distribution of rod and cone cells in the retina
Fovea has highest light intensity so cone cells found there
Peripheries of retina has low light intensity so rod cells found there
Why are cone cells found in the Fovea in the retina but not rod cells
Has highest light intensity
Rod cells too sensitive
Cone cells need this stronger stimulation
How do rod and cone cells allow you to see both day and night
The combination of the two
Means different stimuli
How do hormones reach the cells they affect?
Travel in the bloodstream
What is an endocrine system
Non-reversible and slow acting
What are chemical mediators
Chemicals that are released from certain cells and effect cells in their immediate vicinity
(Act at cellular level)
Describe an inflammatory response
Chemicals released increase blood flow and permeability of the capillary
Leads to rise in temperature and swelling of infected area
What are 2 examples of chemical mediators
Prostaglandins
Histamine
Describe prostaglandins
Made from fatty acids
Found in cell membrane
Release after injury
Affect blood pressure and neurotransmitters
Cause dilation of arteries
Increase permeability of capillaries
Describe histamine
Stored in white blood cells
Released after injury or in response to an allergen
Increase permeability of capillary
What is IAA
Example of plant growth factor
Causes plant cells to elongate
How is auxin positively phototropic
Auxin in tip causes cells on shaded side to elongate
What is auxin
Plant hormone
IAA
Why are gelatin blocks used in plant experiment
It blocks electrical signals
Used to show its chemicals not electricity which causes phototropic
Why is mica used in plant experiments
Blocks chemicals
No response if mica in shaded side, shows must be chemicals causing effect
Responsive if mica on light side
Shows unequal distribution of auxin in tip which is why it bends
Why does the tip of a plant bend
Unequal distribution of auxin in the tip
How does IAA get transported from the light side of the tip to the dark side of the tip
Diffusion
What happens if auxin is in the roots of a plant
Causes cells to shrink
Opposite of what happens to the shoots
