Response To Stimuli - Nerves And Hormones Flashcards
What is a taxis?
A taxis is a simple response whose direction is determined by the direction of the stimulus.
What is Positive taxis??
Movement towards a stimulus
What is negative taxis?
Movement away from a stimulus!!
What is tropism?
The growth of part if a plant in response to a directional stimulus.
What is positive tropism ?
Growing towards the stimulus in response
What is negative tropism?
Growing away from the direction if the stimulus in a negative response
Three types of tropism…
Phototropism
Geotropism
Hydrotropism
Central nervous system is made up of…
The brain and the spinal cord
Peripheral nervous system is made up of…
Pairs of nerves that originate from either the brain or the spinal cord.
(The nerves in the systems)
Peripheral nervous system is divided Into…..
Sensory neurones & motor neurones
The motor nervous system can be subdivided into….
Voluntary nervous system &
Autonomic nervous system
Rod cells - frequency in the retina?
More numerous !!
Cone cells - frequency in the retina…
Less numerous!!
Rod cells - shape and pigment ?
Rod shaped
Rhodopsin
Cone cells - shape and pigment ?
Cone shaped
Iodopsin - this pigment occurs in 3 forms!!
Rod cell pigment properties (rhodopsin) ??
Very sensitive to light and responds to low light intensities. But is unable to distinguish colour (monochromatic)
Come cells - pigment properties (iodopsin) ??
Sensitive to only high light intensities and able to distinguish colour.
Rod cells - synaptic connections??
Groups if rods synapses with a single bipolar neurone - they display convergence !!
Cone cells - synaptic connections??
A 1:1 connection between cone cells and bipolar neurones!
What is a stimulus ?
A detectable change in the external or internal environment of an organism that produces a response In the organism.
Why do some optic cells contain black pigment??
This pigment absorbs the light and stops the light from being reflected!!
Explain how rod cells have high sensitivity??
More than one rod cell to each bipolar neurone gives an accumulate / higher impulse and reaching the active potential in lower light intensities because they can overcome the threshold value!
Which part of the retina has the highest number if receptor cells??
The FOVEA
A myelinated axon conducts impulses faster than a non-myelinated axon. Explain the difference??
In myelinated…..
1. The action potential / depolarisation only at nodes of Ranvier.
⭐️⭐️⭐️
2. Nerve impulse jumps from node to node/ saltatory conduction
⭐️⭐️⭐️
3. Action potential / impulse does not travel along whole length
Resting potential = ?
Potential difference across the plasma membrane when the cell is at rest
Action potential = ?
The brief change in polarity when the neuron is activated (nerve impulse )
The cells of the body need to communicate with one another. What is the name given to this process of communication???
Cell signalling 💕💕
Sensory neurones??
Transmit nerve impulses from receptors to CNS ✨✨✨
Relay neurones ??
Transmit nerve impulses between other neurones ✨✨✨
Motor neurones ???
Transmit nerve impulses from CNS to effector ✨✨✨
The reflex arc = ?
Stimulus ⬇️ Receptor ⬇️ Sensory neuron ⬇️ Relay neuron ⬇️ Motor neuron ⬇️ Effector ⬇️ Response
The purpose / use of the reflex arc ??
Reflex arc enables a rapid response to a stimulus, without the need to involve the brain.
✨✨✨
V. Useful for protecting the body from damage!!!
Nerve impulses always travel from…..?
From Densrites to the Axon!! ✨✨✨
Effect of myelin sheath on conduction?
Myelin sheath helps speed up transmission of nerve impulses (conduction)
Schwann cells = ?
Schwann cells wrap around axon multiple times…..
Multiple layers of cell membranes….
INSULATED nerve cells (prevents the nerve impulses passing through it)
Nodes of Ranvier = ?
Gaps between Schwann cells where the axon is exposed 💁
Saltatory conduction = ?
Nerve impulses jumping from node to node 🍸👯🎉
Threshold to fire ?
The minimum amount of stimulus required in order to activate the nerve cell and cause an action potential
🙌💕✨
A.K.A. The all or nothing law
Cell signalling = ?
Communication between cells!
E.g. Communication between nerve cells across a synapse
