Biology Chapter 12 (Coordination and Response) Flashcards
Define stimuli?
Changes in an organisms environment is called stimuli
Define receptors?
Cells that sense the stimuli
How do organisms respond to stimuli?
Using Effectors
Why do Animals need a more effeective response?
As they need to respond quickly to protect thmselves and to catch food.
Name 2 methods of sending information from receptors to effectors?
- Nerve receptors and nerve makeups of nervous system
- By means of hormones which are a part of Endocrine system
Define sensitivity?
The ability to detect stimuli and carry out responses
How are signals transfered in the nervous system?
Electrical impulses
How are signals transferred in Endocrine system?
Using Hormones
What are the two types of nervous systems?
- Central nervous system
- Peripheral nervous system
What are the two nervous systems under peripheral nervous system?
- Autonomic nervous system
- Somatic nervous system
What are nervous system cells made of?
Neurons
What is the longest fibre in Nervous cells?
Axon- more than a meter long
What are the shorter fibres in nervous cell called?
Dendrites and Dendrons
Function of dendrites?
Pick electrical signals from other neurons nearby called impulses, cell body, along with axon
Define Myelin?
A layer of fat and protein that surrounds the nerve fibres of active animals, like mammals.
Function of Myenlin?
It insulates the nerve fibres so that impulses could be sent much faster
What are the 3 types of neurons?
- Sensory neuron
- Relay Neuron
- Motor neuron
Describe the basic function of nervous system?
The sensory neuron detects the stimuli and sends those impulses to the CNS (Central Nervous System). The CNS then send a signal to the Motor Neuron which makes it contract and move the muscle where the stimuli happened.
What are the 2 types of Nervous action?
- Voluntary actions
- Involuntary actions
Define Voluntary action?
An action that we do out of our will or we do it conciously.
Define Involuntary action?
An action which occurs without out conscious choice or will. Ex(Breathing, Heart beat, Blinking)
Function of Sensory Neurone?
picks impulses from the sensory receptor and sends it to the spinal cord along the axon of the receptor cell.
Function of Relay Neurons?
They pass the impulses onto the effector.
Define Reflex arc?
The pathway in which the nerve impulse passes along Sensory, Relay and Motor neurone
Define reflex action?
Reflex action is also an involuntary action. It is a nearly instantaneous movement in response to stimuli. It is an automatic action.
Define Synaptic clefts?
The space in between the axon of on neuron and the dendrites of another.
Define receptors.
Cells or group of cells that detect stimuli.
Example:
i.)Eyes: cones and rods in the retina are receptors.
Define conjunctiva.
A thin, transparent membrane in font of the eyes helps to protect parts behind it.
How is conjunctiva kept moist?
By the tear glands
Define Retina.
A tissue at the back of the eye that contains receptor cells that respond to light
Define Fovea.
Part of the retina packed with rods and cones for vision.
Define blind spot.
Where the optic nerve leaves the retina, lack of rods and cones results in no image being made when light fall on it
Define Choroid.
It is behind the retina, black in color, rich in blood vessels to provide nourishment for the eyes and absorbs all the light to prevent them rom being scattered.
Define rod cells.
Sensitive to dim light, black and white only as it does not respond to color.
Define Cone cells.
Distinguish between the different colors of light-colored vision, only responds when there is quite bright light.
How many cone types do we have and what are they sensitive to?
3 cones types, they are sensitive to red, blue and green
How are rod cells distributed?
Found all throughout the retina, but none in the center of the fovea or in the blind spot.
How are Cone cells distributed?
They are concentrated in the Fovea.
Define Iris.
It is in front of the lens, it is a colored part of your eye and changes the diameter of the pupil to control how much light enters.
Define optic nerve.
The nerve that carries electrical impulses from the retina to the brain
Define pupil.
A circular gap in the centre of the iris through which light can passs.
Define circular muscles.
Makes pupils constrict or become smaller.
Define Radial muscles.
Runs outwards from the edge of the pupil and makes the pupil dilate or become larger.
Define Iris reflex.
Contracting and dilating of the iris in response to change in light intensity
Define cornea.
The cornea is responsible for the bending of light
Define lens.
A transparent structure in the eye, which changes shape to focus light rays onto the retina
How is the image formed and interpreted as sight?
- Light from the object is refracted and focused onto the retina.
- The image is formed real, inverted and smaller than the object
- The image will be detected by rods and cones which cause nerve impulses.
- Nerve impulses are transmitted along the optic nerve to the optic centre in the cerebral cortex of the brain.
- The optic centre in the brain interprets the nerve impulses and “sees” an upright image of the object in the brain.
Define accommodation.
Changing the shape of the lens to focus on objects at different distances from the eye.
Define suspensory ligaments.
Strong, inelastic fibres that hold the lens in position. When under tension, the pull the lens into a thinner shape.
Define Ciliary muscle.
A circle muscle surrounding the lens, and joined to it by the suspensory ligaments; When it contracts it slackens the ligaments and causes the lens to become fatter.
Why do eyes get tiered after reading up close?
Because the light rays from near objects are diverging and so the ciliary muscles have to contract inorder to properly refract the light.
Why is it considered resting when you look into the distance?
Because the light rays from a distance are parallel meaning the ciliary muscles relax inorder to refract it and so they can rest.
Define color blindness.
When there is a defect with one or more of the cone cells. It is Inherited.
Define hormones.
Chemicals that are produced in a gland and are carried in the blood.
Define Endocrine glands.
Glands that secrete hormones. They are Ductless glands
Define Target organ.
Organs whose activity is altered by a hormone.
What does the pineal gland produce?
Melatonin
Function of Melatonin?
It acts as the biological clock and has many target organs.
What does the Thyroid gland produce?
Thyroxin
What is the function of thyroxin?
It alters metabolic rate and its target organ is the Liver.
What does Adrenal gland produce?
Adrenalin
Function of adrenaline.
It prepared the body for vigorous activity and causes the fight or flight response.
What does pancreas produce?
Insulin
What is the function of insulin?
It helps 𝐜𝐨𝐧𝐭𝐫𝐨𝐥 𝐛𝐥𝐨𝐨𝐝 𝐬𝐮𝐠𝐚𝐫 𝐥𝐞𝐯𝐞𝐥𝐬 and its target organ is 𝐋𝐢𝐯𝐞𝐫.
What does Ovaries produce?
estrogen
What is the function of estrogen?
It helps 𝐜𝐨𝐧𝐭𝐫𝐨𝐥 𝐭𝐡𝐞 𝐦𝐞𝐧𝐬𝐭𝐫𝐮𝐚𝐥 𝐜𝐲𝐜𝐥𝐞 and its target organ is the 𝐔𝐭𝐞𝐫𝐮𝐬
What does testes priduce?
Testosterone.
Function of testosterone.
Causes the development of 𝐦𝐚𝐥𝐞 𝐜𝐡𝐚𝐫𝐚𝐜𝐭𝐞𝐫𝐢𝐬𝐭𝐢𝐜𝐬 and its target organ is many.
Where are adrenal glands located and how many are there?
2 adrenal glands, one above each kidney
How does your body react during fight or flight response?
. Heart beats faster
. Brain and muscles are supplied with more oxygen quickly
. Energy for fighting or running away is obtained
. Blood vessels in skin and digestive system contract
. Pupils in eyes widen to allow you to see more
. Releases glucose in blood, so muscles get more energy
Define positive response in plants.
Growth towards stimuli
Define Negative response in plants.
Going away from stimuli
Define Tropism.
Growth response by a plant in which the direction of the growth is affected by the direction of stimulus.
Define Phototropism.
A response in which a part of the plant grows towards or away from the direction the light is coming from.
Define Gravitropism.
A response in which a part of the plant grown towards or away from the gravity.
What does a positive reaction for plants mean?
When it grows towards the stimulus
What does a negative reaction for plants mean?
If growth is away from the stimulus
What is the response of shoots to stimuli?
.Negatively gravitropic
.Positively Phototropic
Advantage of shoots growing towards the light?
To trap more light from photosynthesis.
Advantages of shoots growing against Gravity?
. Shoots of a germinating seed grows out of the soil
. More chances for pollination and seed dispersal
What is the response of roots to stimuli?
. Positively Gravitropic
. Negatively Phototropic
Advantages of a root growing towards gravity.
. To anchor the plant
. To search for water
. To ensure that the root of a germinating seed always grows downwards, no matter the position of the seed.
