Coordination & Response (Homeostasis, eye, reflex arc, tropisms) Flashcards
What does the CNS consist of?
The brain & spine
What is an effector?
A muscle producing a response
What carry signals from the receptor to the brain and spinal cord?
Sensory neurone
What carries messages within the CNS?
Relay neurone
What carries a signal from the CNS to the effector?
Motor neurones
What 3 things does a co-ordinated response require?
Stimuli, receptor, effector
What is homeostasis & give 2 examples in humans
The regulation of internal conditions
- Control of water content –> osmoregulation
- Temperature regulation –> thermoregulation
What is a synapse?
A gap where two neurones meet.
What happens at a synapse?
Signals cross the gap using chemicals - one neurone releases a chemical called a neurotransmitter and it diffuses across the gap making the next send another electrical signal.The neurotransmitter is then broken down by enzymes at the 2nd neurone.
Why are there reflex actions?
Sometimes a very quick response is needed
What are reflex actions?
Actions without unconscious thought
How do plants respond to stimuli?
Using tropisms such as geotropism, phototropism and hydrotropism
Geotropism response of roots?
Roots carry out positive geotropism, towards the earth & gravity (downwards) –> towards water
In root placed horizontally auxin will collect in bottom, making it grow less and bend towards gravity
Geotropism response of shoots?
Shoots carry out negative geotropism, away from gravity –> to get sunlight
In a shoot placed horizontally, bottom side contains more auxin making it grow less than top side and grow against gravity.
Explain positive phototropism in stems?
Stems want to grow towards the light to get the maximum sunlight. Auxins will collect in the shaded side, meaning this side grows longer, bending the shoot towards the light.
Is the hormone (endocrine) or nervous system faster?
Nervous system
Which response lasts longer: the hormone (endocrine) or nervous system?
Endocrine
Which of the hormone (endocrine) or nervous system has a localised response, and which is more widespread?
Nervous is localised, endocrine is widespread
What sort of messages are sent by the endocrine and nervous systems?
Nervous is an electrical impulse whereas endocrine is a chemical messenger/hormone
What is the message of the endocrine system transmitted by?
The blood stream
What is the message of the nervous system transmitted by?
Neurones
Describe the hormone: Anti-Dieuretic Hormone (ADH) {Secreted, where in body responds, effect}
It is secreted from the pituitary gland
The collecting duct of the nephron in the kidneys responds
It causes the duct to be impermeable or permeable according to whether water needs to be conserved or lost. More secreted –> more reabsorbed
Describe the hormone: Adrenaline {Secreted, where in body responds, effect}
Secreted from the adrenal gland
Heart, lungs and liver respond
It prepares body for physical activity by increasing heart and breathing rate (providing muscles with oxygen rich blood)
Describe the hormone:Insulin {Secreted, where in body responds, effect}
Secreted in the pancreas
Liver cells respond
It lowers blood glucose levels, stimulating the liver cells to convert glucose into glycogen (and absorb more)
Describe the hormone: Testosterone {Secreted, where in body responds, effect}
Secreted in the testes
It helps develop secondary sexual characteristics
Including growth of genitals and body hair
Describe the hormone: Oestrogen {Secreted, where in body responds, effect}
Secreted in the ovaries
Responds in the uterus lining
It repairs the uterine lining and causes ovulation
Describe the hormone: Progesterone {Secreted, where in body responds, effect}
Secreted in the ovaries (corpus luteum)
Responded to in the uterus lining
It regulates menstrual cycle & thickens uterine lining ready to implant a fertilised egg
What is the function of the eye as a receptor?
The eye is a receptor of light, it has light receptor cells in its retina. These cells turn stimuli into electrical impulses.
What is the pupil?
The gap between the iris which lets light in
What is the lens
The first fine tuning of the image which changes shape to focus it
What is the iris
The coloured part of the eye which controls the amount of light entering the eye using two sets of muscles: radial (wheel spokes) and circular muscles.
What is the ciliary muscles
These adjust the thickness of the lens
What is the suspensory ligament
This holds the lens in place attaching it to the ciliary muscles
What is the retina
The area at the back of the eye where the light receptors are, which transduce light energy into electrical impulses
What is the fovea
The area of the center of the retina where there is more cones, giving a sharper image (an image is clearer if you look directly at it)
What is the optic nerve?
The nerve that leads from the back of the eye behind the retina that sensory neurones pass impulses from the retina to the brain
What is the cornea?
A curved transparant window at the frontwhich lets light into the eye
What is the sclera?
The opaque white part of the eyeball
What is the fluid in the eye called
Vitreous humour
What is accommodation?
The changing of the size of the lens to focus images
Accommodation - What happens if there is a distant object?
The lens will become flatter and less convex to focus the image as the rays are almost parallel when they enter and don’t need to refract as much to hit the retina.
The ciliary muscles relax
Suspensory ligaments pull tight
Accommodation - What happens if there is a close object?
The lens becomes rounder and more convex as the rays are diverging when they enter the eye. They need to refract them more to hit the retina
Ciliary muscles are slack
Suspensory ligaments are slack
What will happen if the light intensity is too much?
The iris will contract to make the pupil smaller as too much light could be dangerous for the eye.
What will happen if the light is dim in the eye?
The iris will relax to make the pupil dilate so that it can see an image.
What happens during vasoconstriction? {vessels smaller}
The thermoregulatory center of the hypothalamus in brain detects the body is too cold
When blood vessels near the skin shrink, reducing the blood which runs by the surface so that less heat is lost to the air.
Also, hair erector muscles pull hair on end. The erect hair traps heat.
What is vasodilation? {vessels larger}
The thermoregulatory center of the hypothalamus in brain detects the body is too hot
Blood vessels by the skin grow bigger, so that more heat can be lost.
Hair muscles relax, hair lies flat so heat can escape
What are features of the structure of a motor neurone?
A large spread out area with dendrons (tree branches) leading to dendrites (twigs), with the cell body in the middle. It then leads on to take the impulses through the axon which is insulated by a fatty myelin sheath, which increases the speed of the impulse. There is then a branched nerve ending which makes contacts with other neurones/the effector.
What are some functions of the skin?
To resist mechanical damage A barrier of harmful microorganisms An impermeable surface A sense organ Controlling the loss of heat
What does homeothermic mean?
This means the animal is warm-blooded, keeping a constant temp
What does endothermic mean?
Heat from inside –> They use physiological changes to generate or lose heat
What is human’s optimum temp?
37 degrees C
What is some plants’ hydrotropism?
Some have positive response –> the roots grow towards the water
What do more auxins in an area do?
Most cases cause additonal cell division, meaning the size of the tissue increases.
What is the peripheral nervous system?
It is parts of the nervous system outside of the CNS (brain & spinal cord) such as the receptors and neurones
What two type of reflex actions are there?
Spinal reflexes eg finger on hot thing
Cranial reflexes involving unconscious part of brain eg pupil dilating or contracting
What type of action is pupil dilation or constriction?
Reflex action (cranial reflex)
opposite of a reflex action
voluntary action
what are hormones secreted by and give examples
endocrine glands
pituitary gland thyroid gland adrenal gland pancreas ovary or testes
hormones are carrird from the endocrine gland to the target organ by?
the bloodstream
What are the blood vessels called that take blood with the waste products in to the kidney to be filtered?
Renal arteries
What are the blood vessels called that bring filtered blood out of the kidneys?
Renal veins
