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Coordination and response Flashcards

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1
Q

What are neurons?

A

nerve cells that carry electrical impulses when stimulated (electrical impulses travel along neurones)

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2
Q

What is a nerve?

A

A bundle of neurones

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3
Q

What does the human nervous system consist of?

A
  1. central nervous system(CNS) - thebrain and the spinal cord
    The role of the CNS is to coordinate messages travelling through the nervous system. When a receptor detects a stimulus, it sends an electrical impulse to the brain or spinal cord, which then sends an electrical impulse to the appropriate effectors.
  2. peripheral nervous system(PNS) - all of the nerves outside of the brain and spinal cord in the body
    This consists of receptor cells (the cells that detect changes in stimuli and send information down the sensory neurones), sensory neurones (the neurones that carry information from receptors) and the motor neurones (the neurones that carry information to the effectors).
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4
Q

What does the nervous system allow us to do?

A
  • Make sense of our surroundings and respond to them
  • Coordinateandregulate body functions (Ex: muscle contraction, pupil dilating in dark, salivation, stomach digestion, liver releases glucose)
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5
Q

What is the function of dendrites?

A

Dendrites receive signals from surrounding neurones. They are branched to allow connections with many neurones

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6
Q

What is the axon?

A

The axon is a long structure off the cell body that electrical signals can rapidly be sent through. Its long length allows for signals to be sent rapidly. This means that less time is wasted transferring the impulse from one cell to another. The axon is insulated by a fatty sheath with small uninsulated sections along it (called nodes). The electrical signal jumps from one node to the next.

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7
Q

What is the axon terminal?

A

The axon terminal is where signals are passed to the next neuron over the synapse (Nerve impulses can only be sent one way)

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8
Q

What are the three main types of neurones?

A

Sensory neurones
Relay neurones
Motor neurones

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9
Q

What do sensory neurones do and look like?

A
  • Sensoryneurones carry impulsesfrom sense organs to the CNS(brain or spinal cord)
  • Sensory neurones arelongand have acell body branching off the middle of the axon
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10
Q

What do motor neurones do and look like?

A
  • Motorneurones carry impulsesfrom the CNS to effectors(muscles or glands)
  • Motor neurones arelongand have alarge cell body at one end with long dendrites branching off it
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11
Q

What do relay neurones do and look like?

A
  • Relayneurones are found inside the CNS andconnect sensory and motor neurones
  • Relay neurones areshortand have asmall cell body at one endwith many dendrites branching off it
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12
Q

What are the two types of responses?

A
  1. Voluntary response (one where you make aconscious decisionto carry out a particular action therefore itstarts with your brain)
  2. Involuntary response or reflex response (doesnot involve the brain as the coordinatorof the reaction and you arenot awareyou have completed it untilafteryou have carried it out)
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13
Q

Whats the difference between voluntary and involuntary responses?

A

Involuntary actions are usually ones which areessential to basic survivaland arerapid, whereas voluntary responses oftentake longeras we consider what the consequences might be before doing it.

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14
Q

What is a reflex action?

A

A reflex action is a means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors (muscles and glands)

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15
Q

What are the steps in a reflex response?

A
  1. Stimulus is detected by receptor (pain, smell, taste, visual, chemical, pressure) in the skin
  2. Signal is transmitted to the sensory neuron
  3. Sensory neuron passes to a relay neuron in the central nervous system
  4. The relay neuron sends the signal to the motor neuron
  5. The motor neuron carries impulse to the effector muscles/gland which is then stimulated to respond
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16
Q

What is a synapse?

A

A junction between two neurones. Synapses ensure that impulses travel in one direction only
- As this is the only part of the nervous system where messages arechemicalas opposed to electrical, it is theonly place where drugs can act to affect the nervous system

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17
Q

What does a synapse consist of?

A

A synapse consists of a presynaptic cell, a synaptic cleft, and a postsynaptic cell. The presynaptic cell releases neurotransmitters into the synaptic cleft, which then bind to receptors on the postsynaptic cell, triggering a response.

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18
Q

What events happen at a synapse?

A
  1. An impulse stimulates the release of neurotransmitter molecules from vesicles in the presynaptic neurone into the synaptic gap
  2. The neurotransmitter molecules diffuse across the gap (down the concentration gradient
  3. Neurotransmitter molecules bind with receptor proteins on the postsynaptic neurone cell surface
  4. An impulse is then stimulated in the postsynaptic neurone and is carried along
  5. The neurotransmitters are recycled or destroyed once an impulse is sent (destroyed to prevent continued stimulationof the second neurone which would cause repeated impulses to be sent)
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19
Q

What are sense organs?

A

Sense organs are a group of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals

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20
Q

What is skin sensitive to?

A

Sensitive to pressure, temperature and pain
Sense: Touch and temperature

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21
Q

What is the tongue sensitive to?

A

Sensitive to chemicals in food and drink
Sense: Taste

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22
Q

What is the nose sensitive to?

A

Sensitive to chemicals in the air
Sense: Smell

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23
Q

What are the ears sensitive to?

A

Sensitive to sound and movement
Sense: Hearing, balance

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24
Q

What are the eyes sensitive to?

A

Sensitive to light and colour
Sense: sight

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25
Q

What is the function of the cornea?

A

Curved part of eye (transparent lens) that refracts light as it enters the eye

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26
Q

What is the function of the lens?

A

Transparent disc that can change shape to focus light on the retina

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27
Q

What is the function of the iris?

A

Coloured part of the eye that controls how much light enters the pupil

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28
Q

What is the function of the retina?

A

Where light is focused in the eye. Contains light receptor cells (rods detect light intensity, cones detect colour)

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29
Q

What is the function of the optic nerve?

A

Sensory neurone that carries impulses from the eye to the brain

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30
Q

What is the function of the pupil?

A

Opening in eye that allows light to enter

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31
Q

What is the function of the ciliary muscles?

A

Contract or relax to make the suspensory ligaments go slack or tighten respectively, changing the shape of the lens

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32
Q

What is the function of the suspensory ligaments?

A

Attaches lens to ciliary muscles

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33
Q

What is the function of the fovea?

A

A tiny pit located in the retina that provides the clearest vision. The eye lens will focus light on the fovea, almost all of the cone cellsare found and there are no rod cells

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34
Q

What is the blind spot?

A

At the point where the optic nerve joins the retina, there are no light-sensitive rod and cone cells on that part of the retina causes ablind spot, where we cannot detect an object in our peripheral vision even if it is there

35
Q

What is the function of rod cells?

A

Detect differences in light intensity (don’t detect colour), they are highly sensitive to light and are used extensively in dim light and night vision

36
Q

How are rod cells distributed?

A

Rod cells are widely distributed on the retina all around the fovea (there are no rod cells at the fovea) and contribute to peripheral vision

37
Q

What is the function of cone cells?

A

Detect differences in colour. There are3 types of cone cellswhich are sensitive to different colours of light (red, blueandgreen)

38
Q

How are cone cells distributed?

A

Cones are highly concentrated around the fovea where the highest intensity of light hits

39
Q

Why is night vision black and white?

A

It’s because the low light intensity isn’t enough to stimulate cone cells, so only rod cells are stimulated. Only the cone cells can detect colour.

40
Q

What is the pupil reflex?

A

This is areflex actioncarried out toprotect the retina from damagein bright light and protect us from not seeing objects in dim light. Indim lightthe pupildilates(widens) in order to allow as much light into the eye as possible and inbright lightthe pupilconstricts(narrows) in order to prevent too much light entering the eye and damaging the retina

41
Q

What happens to the eye in bright light?

A

If I was in a brightly lit area, the iris would work to reduce the amount of light able to enter my eye. This would happen as the circular muscles in the iris contract and the radial muscles relax (antagonistic pairs). This would cause the pupil to become smaller, so less light enters the eye. This means the light sensitive cells of the retina would have an appropriate amount of light to be able to send impulses to the brain along the optic nerve to form the image I see.

42
Q

What happens to the eye in dim light?

A

If I was in a dimly lit area, the iris would work to increase the amount of light able to enter my eye. This would happen as the circular muscles in the iris relax and the radial muscles contract (antagonistic pairs). This would cause the pupil to become larger, so more light enters the eye. This means the light sensitive cells of the retina would have an appropriate amount of light to be able to send impulses to the brain along the optic nerve to form the image I see.

43
Q

What is accomodation?

A

Accommodation is the function of the eye in focusing on near and distant objects. The lens iselasticand its shape can be changed when thesuspensory ligamentsattached to it becometightorloose, these changes are brought about by thecontractionorrelaxationof theciliary muscles

44
Q

What happens to the eyes when you view far objects?

A

Far objects (range in angle of light is lesser so lens must be thinner)

  1. Ciliary muscles relax
  2. Suspensory ligaments tighten and are pulled taut
  3. Lens becomes thinner

As a result, light is refracted less by lens allowing eye to focus on far object

45
Q

What happens to the eye when you view near objects?

A

Near objects (range in angle of light is greater so lens needs to be thicker)

  1. Ciliary muscles contract inwards
  2. Suspensory ligaments slacken
  3. Lens becomes fatter

As a result, light is refracted more by lens to focus on the near object

46
Q

What is a hormone?

A

A hormone is a chemical substance produced by a gland and carried by the blood, which alters the activity of one or more specific target organs

47
Q

What do endocrine and exocrine glands do?

A
  • Endocrine glands secrete substances into the bloodstream (e.g. pituitary gland releases ADH)
  • Exocrine glands secrete substances onto surface of body (e.g. sweat or salivary glands)
48
Q

What is the endocrine system?

A

The glands that produce hormones in animals are known collectively as theendocrine system

49
Q

What is the livers function with hormones?

A

The liver regulates levels of hormones in the blood; transforming or breaking down any that are in excess

50
Q

What is the difference between nervous control and hormonal control?

A

Nervous control sends signals fast through neurones (electrical impulses) and have a short-term effect, happens until nerve impulses stop (Ex: muscle contraction, gland secretion)
Hormonal control sends signals slowly though blood (chemical messenger). It has a long-term effect, happens until hormone is broken down

51
Q

What is adrenaline’s source, role and effect?

A

Source: Adrenal gland (on top of kidney)
Role: Causes liver to break down glycogen and release glucose into bloodstream (only fight and flight response)
Effect: Increases heart and breathing rate and dilates pupils

52
Q

What is insulin’s source, role and effect?

A

Source: Pancreas
Role: Used when blood sugar is high to lower blood glucose levels
Effect: Causes liver to absorb glucose from the bloodstream and convert it into glycogen for later use.

53
Q

What is testosterone’s source, role and effect?

A

Source: Testes
Role: Main sex hormone in males
Effect: Development of secondary sexual characteristics in males (Growth of penis and testes, growth of facial and body hair, muscles develop, voice breaks, testes start producing sperm)

54
Q

What is oestrogen’s source, role and effect?

A

Source: Ovaries
Role: Main sex hormone in females
Effect: Development of secondary sexual characteristics in females (Breasts develop, body hair grows, menstrual cycle begins, hips get wider)

55
Q

What is glucagon’s source, role and effect?

A

Source: Pancreas
Role: Hormone used when blood sugar levels are low but not a fight or flight situation
Effect: Causes the liver to break down glycogen into glucose and release it into the bloodstream

56
Q

When is adrenaline secreted?

A

Adrenaline is the hormone secreted in fight or flight situations

57
Q

Effect of adrenaline on body?

A
  • Increased pupil diameter (pupils dilate so as much light enters the eyes as possible so more information can be sent to the brain)
  • Breathing becomes faster and deeper (so more energy for muscle contraction)
  • Heart beats faster (to pump more nutrients to cells, ensures muscles are well prepared for high levels of activity in a flight or fight situation)
  • Diverting blood flow towards musclesand away from non-essential parts of the body such as the gut (to ensure the reactants of respiration are as available as possible)
  • Glucose released from the liver (more nutrients for respiration, increased glucose in the blood and helps deliver more important glucose to muscles for respiration)
  • Hair stands on end (goosebumps)
58
Q

What is homeostasis?

A
  • Homeostasis is the maintenance of a constant internal environment
  • Homeostasis means thatinternal conditionswithin the body (such as temperature, blood pressure, water concentration, glucose concentration etc)need to be kept within set limitsin order to ensure that reactions in body cells can function and therefore the organism as a whole can live. When one of these conditions deviates far away from the normal if not brought back within set limits thebody will not function properlyand the eventual consequence without medical intervention will be death
59
Q

What is the negative feedback loop and how does it work?

A
  • Homeostasis always tries to keep a variable in our body at a set point using a negative feedback loop. Negative feedback is when a fluctuation in a particular parameter, such as body temperature, is reduced so that it returns to its normal range of functioning. This is done by triggering a sensor that stimulates a response in an effector that reduces the fluctuation. In other words, any change is counteracted so that it returns to its set-point.
  • A negative feedback control is when the change in hormone level acts as a signal to cancel out that change, so when the blood hormone level is low, hormone production is stimulated; when it is high, it is inhibited.
60
Q

How are blood glucose levels controlled

A
  • Blood glucose levels are controlled by a negative feedback mechanism involving the production of twohormones-insulinandglucagon. Both hormones which control blood glucose concentration are made in thepancreas
  • Insulinis produced whenblood glucose risesandstimulates liver and muscle cells to convert excess glucose into glycogen to be stored (it decreases blood glucose concentration). It’s most often produced directly after eating a carbohydrate rich meal.
  • Glucagonis produced whenblood glucose fallsandstimulates liver and muscle cells to convert stored glycogen into glucose to be released into the blood
61
Q

What is type 1 diabetes?

A

Type 1 diabetesis a condition where the blood glucose levels are not able to be regulated as theinsulin-secreting cells in the pancreas are not able to produce insulin (scientists think this is because people’s immune system has destroyed the cells in the pancreas that produce insulin). This means that blood glucose levels are oftenfar too high

62
Q

What is the treatment for type 1 diabetes?

A

Treatment: Insulin injections (The extra insulin causes the liver to convertglucose into glycogen, whichreducesthe blood glucose level)

63
Q

What do people with type 1 diabetes have to do?

A

People with Type 1 diabetes have tomonitortheir blood glucose levels throughout the day as their levels ofphysical activityand theirdietaffect the amount of insulin needed. They can help tocontroltheir blood glucose level by being careful with theirdiet- eating foods that will not cause large increases in blood glucose level, and byexercising, which can lower blood glucose levels due to increased respiration in the muscles

64
Q

What internal temperature does the human body maintain and why?

A

The human body maintains the temperature at which enzymes work best, around37°C. If body temperature increases over this temperature,enzymes will denatureand become less effective at catalysing reactions such as respiration

65
Q

What happens when temperature changes?

A

When the temperature changes, sensory neurons from heat receptors in the skin detect this information and send it as impulses through nerves to the thermoregulatory centre in the hypothalamus.

66
Q

What is the purpose of the fatty tissue?

A

Insulation: Fat is an insulator, so when the external temperature fluctuates, it prevents our internal temperature from similarly fluctuating. This is because it traps heat inside our body and slows down the warming up of our body from an external source.

67
Q

What does the body do when temperature increases?

A

Vasodilation (Widening of arterioles which increases blood flow to the surface capillaries therefore rate of heat loss from the body increases)
Sweating
Hairs lie flat

68
Q

How does vasodilation cool the body down?

A

When the body temperature rises, the hypothalamus detects this and sends nerve impulses to the arterioles supplying the skin. The smooth muscle in the walls of these arterioles relaxes, causing the arteriole to dilate. This means more blood flows through capillaries closest to the surface of the skin (what causes skin to be red in hot weather) and less blood flows through the shunt vessel so heat can radiate out of the body at an increased rate

69
Q

How does sweating cool the body down?

A

When the body temperature rises, the hypothalamus detects this and sends signals to sweat glands to increase sweat production. The water in sweat absorbs the heat from the body and evaporates from the surface of the skin taking the heat with it.

70
Q

How does hairs lying flat cool the body down?

A

The hair erector muscle is relaxed, allowing the hair to lie flat against the skin, so no air is trapped close to the skin, so we are insulated less (more air is circulated). This is less effective in humans as we do not have as much body hair/ fur as some animals.

71
Q

What does the body do when the temperature decreases?

A
  • Vasoconstriction (Narrowing of arterioles which decreases blood flow to the surface capillaries therefore rate of heat loss from the body decreases)
  • Shivering (rapid, involuntary contraction and relaxation of the muscles)
  • Pilli erection (goosebumps, the hairs stand upright)
72
Q

How does vasoconstriction increase body temperature?

A

When the body temperature drops, the hypothalamus detects this and sends nerve impulses to the arterioles supplying the skin. The smooth muscle in the walls of the arterioles contracts which constricts the lumen. This causes less blood to flow through capillaries close to the surface of the skin and more blood is shunted away from the surface of the skin so less heat radiates from the body (as there is less blood exposed to the surface of the skin)

73
Q

How does shivering increase body temperature?

A

When the body temperature drops, the hypothalamus detects this and sends nerve impulses to the muscles to start shivering. Shivering generates heat because muscles require energy to contract and this energy is supplied by respiration. During respiration, some heat is always lost as heat energy. Therefore as the muscles contract more, more heat is generated. (This is also why we breathe deeper when cold because carbon dioxide needs to be excreted)

74
Q

How does pilli erection increase body temperature?

A

The erector muscle contracts, pulling the hair to stand up straight. This allows the hair to trap air close to the skin. As air is an insulator, it traps heat close to the skin, warming up the body.

75
Q

What is a tropism?

A

The growth response of an organism towards or away from a stimulus
- Tropisms can be either positive or negative; towards is a positive response and away is a negative response
- These responses are slower than animal responses

76
Q

What is auxin?

A

A growth regulating hormone that loosens the cell wall and stimulates cell elongation. It is produced in the shoot tip and diffuses through the plant from the shoot tip. It is unequally distributed in response to light and gravity. Auxin moves away from light, accumulating on the shaded side. It is also produced at the root tips and inhibits cell elongation on the bottom side of the root.

77
Q

What is phototropism?

A

A response in which parts of a plant grow towards or away from the direction of the light source

78
Q

What is a positive and negative phototropic response?

A
  • A positive phototrophic response is shoots as they grow towards light, they must do this so that the leaves can absorb the maximum amount of sunlight
  • A negative phototropic response is roots as they grow away from light
  • In phototropism, auxin moves to the part of the plant receiving less light. This causes the cells on the shaded part of the plant to elongate, making the plant bend towards the light.
79
Q

How do you investigate phototropism?

A

Take three identical plants and set them up in cardboard boxes. For plant A, place it in a light proof box with a single hole, for plant B, place it in a lightproof box with a hole but put it on a clinostat (revolves slowly so all parts of the shoot are exposed to light), for plant C, place it in a lightproof box in complete darkness.

The seedlings in A growtowardsthe light source, in B the effect of the light only coming from one direction has beencancelled outby using aclinostat(this means all sides of the seedlings get anequal amount of lightso they do not curve towards the light source but grow straight up) and in C the seedlings grow straight uplooking for lightand the plant becomes tall and slender with yellowing leaves due to the lack of light

80
Q

What is a positive and negative gravitropic response?

A
  • A positive gravitropic response is roots as they grow towards gravity, they must do this to anchor the plant and absorb water and minerals from the soil particles
  • A negative gravitropic response is shoots as they grow away from gravity
  • In gravitropism, the auxin gathers on the lower side of the plant. This has different effects on different parts of the plant. In the shoot, auxin stimulates growth, so the stem curves upwards and in the root, auxin slows growth, so the root curves down
81
Q

What is gravitropism?

A

A response in which parts of a plant grow towards or away from gravity (also called geotropism)

82
Q

How do you investigate gravitropism?

A
  • Add some damp cotton wool to two petri dishes
  • Place 3 bean seedlings in the cotton wool in each petri dish
    • A - radicle facingdownwards
    • B - horizontally
    • C - radicle (root grows from here) facingupwards
  • Cover each dish with a lid
  • Attach one petri dish to a support so that it’s on its side. Attach the second petri dish to a clinostat (as shown in the diagrams above).
  • Place both in alight-proof box(so that the seedlings are in complete darkness), leave for two days and then observe growth of the seedlings
83
Q

What are the results for the gravitropism experiment?

A
  • In the first petri dishall radicles (roots) have grown downwards(positive gravitropic response) regardless of which way they were initially facing (horizontal, up or down) andall plumules (shoots) have grown upwards(negative gravitropic response)
  • In the second petri dish, all radicles and all plumules have all grownneither up nor downbut straight outwardsin whichever direction they were placedas theeffect of gravityhas beencancelled out by the revolving of the clinostat- they have shown no gravitropic response at all
  • The experiment needs to be done in a lightproof box in order tocancel out the effect of light on the growth of the seedlings

Biology IG (24 decks)

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