Stimuli and Response Flashcards
What is a tactic response (taxis)?
-Directional movement in response to a stimulus, the direction of the stimulus affects the response
What is kinetic response (kinesis)?
-Non-directional (random) movement in response to a stimulus, the intensity of the stimulus affects the response
What is a sensory neurone?
-Transmits electrical impulses from receptors to the CNS
What is a motor neurone?
-Transmits electrical impulses from CNS to effectors
What is a relay neurone?
-Transmits electrical impulses between sensory neurones and motor neurones
Why are simple reflexes involuntary?
-The pathway of communication doesn’t go through conscious parts of the brain
What is phototropism?
-The growth of a plant in response to light
How do roots and shoots grow in response to light?
-Roots=negatively phototropic
-Shoots=positively phototropic
What is gravitropism?
-The growth of a plant in response to gravity
How do roots and shoots grow in response to gravity?
-Roots=positively gravitropic
-Shoots=negatively gravitropic
Where is auxin produced?
-In the tips of roots and shoots and diffuses down the plant
What does auxin stimulate?
-Growth in shoots
-Inhibit growth in roots
What does IAA stimulate?
-Cell elongation
What is a resting potential?
-Outside of the membrane is positive and inside of the membrane is negative
What is a generator potential?
-Membrane is stimulated and becomes excited and more permeable
-Allows more ions to move in and out of the cell
-Changes the potential difference
-Bigger stimulus=bigger change of potential difference=bigger generator potential
What is an action potential?
-Generator reaches threshold level
-All same size, strength of stimulus is is measured by frequency of action potentials
Describe the structure of a Pacinian corpuscle
-End of a sensory neurone wrapped in layers of connective tissues called lamellae
What happens when a Pacinian corpuscle is stimulated?
-Lamellae become deformed and press on end of sensory neurone
-Sensory neurone membrane stretches
-Stretch-mediated sodium ion channels become deformed
-Channels open and sodium ions diffuse into cell
-Generator potential created
-If threshold reached->action potential
How do photoreceptors work?
-Light enters eye
-Pigment in photoreceptor breaks down
-Membrane becomes more permeable to sodium ions
-Sodium ions diffuse in
-Generator potential
-If threshold reached->action potential
What are properties of cone cells and where are they found?
-Found in the fovea
-Detect 3 colours->red, yellow and blue
-Sensitive to bright light
-High visual acuity as one cone joins to one bipolar neurone
What are properties of rod cells and where are they found?
-Found in the peripheral parts of the retina
-Detect black and white light
-Sensitive to dim light
-Low visual acuity as many rods join to the same bipolar neurone
What is visual acuity?
-The ability to tell apart points that are close together
What does myogenic mean?
-The heart muscle can contract and relax without receiving signals from nerves
Describe and explain how heart rate is controlled
-The sinoatrial node (SAN) acts as a pacemaker, causes right and left atria to contract at the same time
-Electrical signals are transferred to the atrioventricular node (AVN)
-Electrical signals passed onto the bundle of His
-Then onto the Purkyne tissue which carries the electrical signals into walls of ventricles causing them to contract from the bottom up
