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Animal Responses Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What are the components of the central nervous system?

A

The central nervous system consists of the brain and spinal cord

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2
Q

What are the components of the peripheral nervous system?

A

The peripheral nervous system is made up of the neurones that connect the CNS to the rest of the body.

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3
Q

What is the autonomic nervous system?

A

This is the nervous system that controls unconscious activities

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3
Q

What is the sympathetic nervous system?

A

The sympathetic nervous system gets the body ready for action. It is categorised as the fight or flight system.

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3
Q

What is the somatic nervous system?

A

This is the nervous system that controls conscious activities

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4
Q

What is the parasympathetic nervous system?

A

The parasympathetic system calms the body down. It is the rest and digest system.

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5
Q

What is the function of the hypothalamus?

A

Found beneath the middle part of the brain its function is to:
- maintain body temperature
- produces hormones that control the pituitary gland

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6
Q

What is the function of the pituitary gland?

A

It is found beneath the hypothalamus and is controlled by it:
- It released hormones and stimulates other glands to release their hormones

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6
Q

What is the function of the cerebrum?

A

It is the largest part of the brain and is divided into two parts called cerebral hemispheres. It has a thin outer layer called the cerebral cortex which is highly folded:
- it is involved in vision, hearing, thinking and learning.

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7
Q

What is the function of the medulla Oblongata?

A

It is at the base of the brain, at the top of the spinal cord:
- It automatically controls heart rate and breathing rate

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8
Q

What is the function of the cerebellum?

A

It is found underneath the cerebrum and it also has a folded cortex:
- It is important for muscle coordination, posture, and coordination of balance.

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9
Q

What is a reflex?

A

A reflex is where the body responds to a stimulus without making a conscious decision to respond. This is because the pathway of communication doesn’t involve conscious parts of the brain.

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10
Q

Why are reflex’s so fast?

A

You don’t need to spend time deciding how to respond to a stimulus, so information travels really fast from receptors to effectors.

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11
Q

What happens during the knee jerk reflex?

A
  1. stretch receptors in the quadricep muscle detect that the muscle is being stretched.
  2. A nerve impulse is passed along a sensory neurone, which communicates directly with a motor neurone in the spinal cord.
  3. The motor neurone carries the nerve impulse to the effector causing it to contract so the lower leg moves forward quickly
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12
Q

What happens during the blinking reflex?

A
  1. Sensory nerve endings in the cornea are stimulated by touch
  2. A nerve impulse is sent along the sensory neurone to a relay neurone found in the CNS
  3. The impulse is then passed from the relay neurone to motor neurones
  4. The motor neurones send impulses to the effectors- the orbicularis oculi muscles that move your eyelids. These muscles contract causing your eyelids to close quickly and prevent your eye from being damaged.
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13
Q

What happens hormonally during the fight or flight response?

A

The pituitary gland is stimulated to release a hormone called ACTH. This causes the cortex of the adrenal gland to release steroidal hormones

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14
Q

What happens neuronally in the fight or flight response?

A

The sympathetic nervous system is activated, triggering the release of a adrenaline from the medulla region of the adrenal gland.

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15
Q

What effects do the sympathetic and nervous systems have during a fight of flight response?

A
  • heart rate is increased
  • the muscles around bronchioles relax so breathing is deeper
  • glycogen is converted to glucose
  • muscles in the skin and gut constrict while heart, lungs etc dilate to redirect blood flow to vital organs
  • erector pili muscles in the skin contract so hairs stand on end.
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16
Q

How does the nervous and hormonal systems affect the control of heart rate?

A
  • the SAN generates electrical impulses that cause cardiac muscles to contract
  • the rate at which the SAN fires is unconsciously controlled by a part of the brain called the medulla
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17
Q

Why do animals need to change their heart rate?

A
  • Animals need to alter their heart rate to respond to internal stimuli
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18
Q

What detector detects low blood pressure?

A

Pressure receptors called baroreceptors in the aorta and the vena cava are stimulated by high and low blood pressure.

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19
Q

What detectors monitor the oxygen level in the blood as well as carbon dioxide and pH?

A

Chemical receptors called chemoreceptors in the aorta, the carotid artery and in the medulla monitor oxygen levels in the blood as well as carbon dioxide and pH

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20
Q

What is the process in the body to respond to high blood pressure?

A
  • Baroreceptors detect high blood pressure
  • impulses are sent to the medulla, which sends impulses along the vagus nerve. This secretes acetycholine, which binds to receptors on the SAN
  • the cardiac muscles cause heart rate to slow down and blood pressure to return back to normal
21
Q

What is the process in the body to respond to low blood pressure?

A
  • Baroreceptors detect low blood pressure
  • impulses are sent to the medulla, which sends impulses along the accelerator nerve. This secretes noradrenaline, which binds to receptors on the SAN
  • the cardiac muscles cause heart rate to increase blood pressure back to normal
22
Q

What is the process in the body to respond to high blood O2, low CO2 or high pH?

A
  • Chemoreceptors detect chemical changes in the blood
  • impulses are sent to the medulla, which sends impulses along the vagus nerve. This secretes acetylcholine, which binds to receptors on the SAN
  • the cardiac muscles cause heart rate to decrease and O2,CO2 and pH levels back to normal
23
Q

What is the process in the body to respond to low blood O2, high CO2 or low pH?

A
  • Chemoreceptors detect chemical changes in the blood
  • impulses are sent to the medulla, which sends impulses along the accelerator nerve. This secretes noradrenaline, which binds to receptors on the SAN
  • the cardiac muscles cause heart rate to increase and O2,CO2 and pH levels back to normal
24
Q

How can you investigate the effect of exercise on heart rate?

A
  1. measure your heart rate at rest
  2. do some gentle exercise for 5 mins then immediately after measure your heart rate again
  3. return to a resting position and measure your heart rate every minute after exercise. Record how long it takes to return back to normal
25
Q

How do you analyse the effect of exercise on heart rate?

A

use the students t test

26
Q

What is skeletal muscle?

A

Skeletal muscle is the type of muscle that you use to move

27
Q

What is the structure of skeletal muscle?

A
  • made up of large bundles of long cells called muscle fibers
  • the cell membrane of the muscle fibers is called the sarcolemma
  • a network of internal membranes called the sarcoplasmic reticulum
28
Q

What is the structure and function of the sarcolemma in skeletal muscle fibers?

A

Areas of the sarcolemma fold inwards across the muscle fibre and stick inside the cytoplasm. These folds are called transverse tubules and they help to spread electrical impulses throughout the sarcoplasm so they reach all parts of the muscle fibre.
- lots of mitochondria

29
Q

What is the structure and purpose of the sarcoplasmic reticulum in skeletal muscle fibre?

A

They are a network of internal membranes. It stores and releases calcium ions that are needed for muscle contraction

30
Q

Why do muscle fibers have lots of mitochondria?

A

They need a lot of mitochondria to provide the ATP needed for muscle contraction

31
Q

Why are skeletal muscle fibres considered multinucleate?

A

They contain many nuclei

32
Q

What are myofibrils in relation to muscle fibers?

A

muscle fibers are made up of lots of long, cylindrical organelles called myofibrils. They’re made up of proteins and are highly specialized for contraction.
myofibrils themselves are made up of bundles of thick and thin myofilaments that move past each other to make muscles contract.

33
Q

What are thick myofilaments made of?

A

Thick myofilaments are made of the protein myosin

34
Q

What are thin myofilaments made of?

A

Thin myofilaments are made of the protein actin

35
Q

Under a microscope what do the dark bands on a myofibril mean?

A

Dark bands contain the thick myosin filaments and some overlapping thin actin filaments.
These are called A bands

36
Q

Under a microscope what do the light bands on a myofibril mean?

A

Light bands contain thin actin filaments only.
These are called I bands

37
Q

What are myofibrils made up of?

A

A myofibril is made up of many short units called sarcomeres.

38
Q

How do myofilaments ‘contract’?

A

They themselves don’t contract. Instead the myosin and actin filaments slide over one another to make the sarcomeres contract.
It is this simultaneous contraction of lots of sarcomeres which means the myofibrils and muscle fibres contract.

39
Q

What are the special structures of a myosin filament?

A

Myosin filaments have globular heads that are hinged, so they can move back and forth.

40
Q

What are the special structure of an actin filament?

A

Actin filaments have binding sites for myosin heads, called actin-myosin binding sites.

41
Q

What two proteins can be found between actin filaments and what is their purpose?

A
  • tropomyosin
  • troponin
    These proteins are attached to each other and they help myofilaments move past each other.
42
Q

How does an action potential cause muscle contraction?

A
  • the action potential triggers an influx of calcium ions
  • ATP provides the energy needed to move the myosin head.
  • the cross bridge is also broken
43
Q

How does the action potential trigger an influx of calcium ions in muscles?

A
  • when an action potential reaches a muscle cell it depolarises the sarcolemma which spreads down the T tubules to the sarcoplasmic reticulum
  • the sarcoplasmic reticulum is stimulated to release stored calcium ions into the sarcoplasm
  • calcium ions bind to troponin, causing it to change shape. This pulls the attached tropomyosin out of the actin-myosin binding site on the actin filament.
  • this exposes the binding site, which allows the myosin head to bind.
  • The bond formed when a myosin head binds to an actin filament is called an actin-myosin cross bridge.
44
Q

How does ATP provide the energy needed to move the myosin head in muscle fibres when stimulated?

A
  • calcium ions also activate the enzyme ATPase, which breaks down ATP to provide the energy needed for muscle contraction
  • the energy released from ATP moves the myosin head which pulls the actin filament along in a kind of rowing action.
45
Q

How does ATP provide energy needed to break the cross bridge when muscle fibres are stimulated?

A
  • ATP provides the energy to break the actin myosin cross bridge, so the myosin head detaches from the actin filament after it has moved
  • the myosin head then reattaches to a different binding site further along the actin filament. A new actin myosin cross bridge is formed and the cycle is repeated.
  • many cross bridges form and break very rapidly, pulling the actin filament along, which shortens the sarcomere, causing muscle to contract
  • the cycle will continue as long as calcium ions are present and bound to troponin
46
Q

What happens after excitation of muscle fibres?

A
  • when the muscle stops being stimulated, calcium ions leave their binding sites on the troponin molecules and are moved by active transport back into the sarcoplasmic reticulum
  • the troponin molecules return to their original shape, pulling the attached tropomyosin molecules with them. This means the tropomyosin molecules block the actin-myosin binding sites again
  • muscles aren’t contracted because no myosin heads are attached to actin filaments
  • the actin filaments slide back to thier relaxed position, which lengthens the sarcomere
47
Q

How does ATP and CP provide the energy for muscle contraction?

A
  • ATP is made by phosphorylating ATP- adding a phosphate group taken from creatine phosphate
  • CP is stored inside the cells and the ATP-CP system generates ATP very quickly
  • CP runs out after a few seconds so its used during short bursts of vigorous exercise
  • the ATP-CP system is anaerobic and its alactic
48
Q

What is a neuromuscular junction and what neurotransmitter does it use?

A

A neuromuscular junction is a synapse between a motor neurone and a muscle cell.
Neuromusclular junctions use the neurotransmitter acetylcholine which binds to receptors called nicotinic cholinergic receptors.

49
Q

How do neuromusclular junctions work?

A

-They work in the same way as synapses between neurones, they release neurotransmitter, which triggers depoalrisation in the postsynaptic cell.
- depolarisation of a mucle cell always causes it to contract if the threshold level is reached
- Acetylcholinesterase stored in clefts on the postsynaptic membrane is released to break down acetylcholine after use.

50
Q

How can some chemicals affect muscle contraction?

A
  • Sometimes a chemical may block the release of the neurotranmitter or affect the way it binds to the receptors on the postsynaptic membrane. This may prevent the action potential from being passd on to the muscle, so the muscle won’t contract
  • this can be fatal if it affects the muscles involved in breathing. If they cannot contract, ventilation cannot take place and the organism cannot respire aerobically.
51
Q

What is the structure and function of skeletal muscle?

A
  • it is controlled consciously
  • made up of many muscle fibres with lots of nuclei
  • under a microscope it has regular cross-striations
  • some fibres can contract very quickly (fatigue easily)
  • some fibres can contract very slowly (fatigue slowly)
    (used for endurance, posture, speed and strength)
52
Q

What is the structure and funtion of smooth muscle?

A
  • it is controlled unconsciously
  • doesn’t have the striped appearance of skeletal muscle
  • it is found in the walls of your hollow internal organs
  • each muscle fibre has one nucleus and are spindle shaped with pointed ends.
  • they contract slowly and don’t fatigue
53
Q

What is the structure and function of cardiac muscle?

A
  • it is controlled on its own (myogenic)
  • it is found in the walls of the heart
  • it is made of muscle fibres connected by intercalated discs which have low electrical resistance so nerve impulses pass easily between cells
  • the fibres are branched to allow nerve impulses to spread quickly through the whole muscule
  • each musclce fibre has one nucleus and is shaped like cylinders
  • you can see some cross striations but the striped pattern isn’t as strong as it is in voluntary muscle
  • the muscle fibers contract rhythmically and don’t fatigue
54
Q

How would you carry out an experiment to monitor muscle fatigue?

A
  1. Attach two electrodes to places on the muscle that you want to record from- in this example we will use the biceps muscle in the arm. A third electrode goes on an inactive point to act as a control
  2. Switch off any other electrical equipment that you don’t need as this generates noise that interferes with the electrical signal from the muscle.
  3. Connect the electrodes to an amplifier and a computer
  4. Keep the muscle relaxed. You should see a straight line on the electromyogram
  5. Then contract the muscle by bending your arm. You should see spikes in the graph as motor units are activated to contract the muscle
  6. If you lift a weight the amplitude of the trace on the graph will increase- there are more electrical signals because more motor units are required to lift the weight
  7. If you continue to hold the weight, your muscle will begin to fatigue. On the electromyogram you will see the amplitude of the trace increase further. This is because your brain is trying to activate more motor units to generate the force needed to hold the weight up.

Biology (26 decks)

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