Chapter 14: Coordination And Response Flashcards
How do electrical impulses travel?
electrical impulses travel along neurones
Describe the types of mammalian nervous system:
(a) the central nervous system (CNS) consisting of the brain and the spinal cord
(b) the peripheral nervous system (PNS) consisting of the nerves outside of the brain and spinal cord
Role of nervous system
coordination and regulation of body functions
Identify of sensory, relay and motor neurones
https://cdn.savemyexams.com/cdn-cgi/image/w=1920,f=auto/uploads/2020/01/The-three-types-of-neurone.png
Describe reflex arc.
-Receptor in the skin detects a stimulus (the change in environment).
-Sensory neuron sends electrical impulses to a relay neuron, which is located in the spinal cord of the CNS. Relay neurons connect sensory neurons to motor neurons.
-Motor neuron sends electrical impulses to an effector.
-Effector produces a response (muscle contracts to move hand away).
What is a reflex action
means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors (muscles and glands)
What is a synapse?
a junction between two neurones
Describe the events at a synapse
(a) an impulse stimulates the release of neurotransmitter molecules from vesicles into the synaptic gap
(b) the neurotransmitter molecules diffuse across the gap
(c) neurotransmitter molecules bind with receptor proteins on the next neurone
(d) an impulse is then stimulated in the next neurone
(From presynaptic neuron to post synaptic neuron)
What do synapses ensure in direction of impulse
ensure that impulses travel in one direction only
What are sense organs?
groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals
Structure of eye
cornea, iris, pupil, lens, retina, optic nerve and blind spot
https://cdn.savemyexams.com/cdn-cgi/image/w=1920,f=auto/uploads/2020/01/The-eye.png
Function of cornea
refracts light
Function of iris
controls how much light enters the pupil
Function of lens
focuses light on to the retina
Function of retina
contains light receptors, some sensitive to light of different colours
Function of Optic nerves
carries impulses to the brain
Describe Pupil reflex
In dim light, the pupil dilates (becomes larger) to allow more light to enter the eye to improve vision. In bright light, the pupil constricts (gets smaller) to allow less light to enter the eye to protect the retina from damage.
How Circular and radial muscles act in pupil reflex
high light intensity: circular muscles contract, radial muscles dilate (relax)
low light intensity: circular muscles relax, radial muscles contract
Accommodation when viewing near objects
near objects : ciliary muscle contract, suspensory ligaments looser which causes lens to become fatter and light is refracted more
Accommodation when viewing fat objects
distant objects: ciliary muscles relax, suspensory ligaments tighten which causes lens to become thinner (light refracted less)
Describe the distribution of rods and cones in the retina of a human
Cones (color) are concentrated in the fovea centralis. Rods (white and black) Found throughout the retina, but none in the center of the fovea or in the blind spot.
Function of rods
Sensitive to low light intensity.
-Detect shades of grey.
-Provide us with night vision, when we can recognize shapes but not colours
Function of cones
Sensitive only to high light intensity.
-Detect color.
-There are three types, sensitive to red, green and blue light
Where is the fovea and it’s function
a region of the retina where the eye sees in particularly good detail.
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Describe a hormone
a chemical substance, produced by a gland and carried by the blood, which alters the activity of one or more specific target organs
Image of endocrine glands
https://mmerevise.co.uk/app/uploads/2022/07/Endocrine-System-2.png
adrenal glands secrete
adrenaline
pancreas secrete
insulin and glucagon
testes secrete
testosterone
ovaries secrete
oestrogen
When is adrenaline secreted
In ‘fight or flight’ situations
Adrenaline effect
(a) increased breathing rate
(b) increased heart rate
(c) increased pupil diameter
role of adrenaline in the control of metabolic activity
(a) increasing the blood glucose concentration
(b) increasing heart rate
Describe homeostasis
the maintenance of a constant internal environment
homeostatic control process
when conditions change from the ideal or set point negative feedback occurs which returns conditions to the set point.
if the level of something rises, control systems are switched on to reduce it again. if the level of something falls, control systems are switched on to raise it again.
control of low blood glucose concentration by the liver
When there is a lack of glucose glucagon is released by pancreas this cause liver to release glucose to blood.
control of high blood glucose concentration by the liver
When there is a high glucose concentration insulin is released by pancreas this cause liver to take glucose out of blood and store it as glycogen
Outline the treatment of Type 1 diabetes
injecting insulin
Identify in diagrams and images of the skin
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maintenance of a constant internal body temperature in mammals
When the temperature changes, temperature receptors in the skin detect this information and send it as impulses through nerves
insulation, sweating, shivering, vasodilation and vasoconstriction
Vasodilation
the muscles in the walls of the arterioles supplying skin-surface capillaries relax, increasing the size of the arteriole lumen. More blood flows, so more heat can be lost to the environment from the blood at a time.
Vasoconstriction
muscles in arteriole walls contract, making the lumen smaller, so less blood travels through the skin at a time, reducing the heat loss per unit time.
Describe gravitropism
a response in which parts of a plant grow towards or away from gravity
Describe phototropism
a response in which parts of a plant grow towards or away from the direction of the light source
Explain the role of auxin in controlling shoot growth
(a) auxin is made in the shoot tip
(b) auxin diffuses through the plant from the shoot tip
(c) auxin is unequally distributed in response to light and gravity
(d) auxin stimulates cell elongation
