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A Level Biology > Animal responses (CH13.6-13.10 and Ch14.5-14.6) > Flashcards

Animal responses (CH13.6-13.10 and Ch14.5-14.6) Flashcards

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1
Q

Central nervous system

A

made up of the brain and spinal cord

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2
Q

Peripheral nervous system

A

made up of the neurones that connect the CNS to the rest of the body

this includes the sensory neurons which carry impulses from receptors to the CNS and the motor neurons which carry nerve impulses from the CNS to effectors

It consists of the somatic and autonomic nervous system

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3
Q

Somatic nervous system

A

under conscious control

it is used when you voluntarily want to do something

Controls conscious activities e,g running

INPUT - sense organs, OUTPUT - skeletal muscles

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4
Q

Autonomic nervous system

A

Works constantly

Under subconscious control

Used when the body does something automatically (involuntary actions), without you deciding you want to do it

e.g controls heartbeat and digestion

INPUT = internal receptors, OUTPUT - smooth muscles and glands

Consists of sympathetic and parasympathetic nervous system

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5
Q

sympathetic nervous system

A

Regulates fight/flight system

sympathetic neurons release the neurotransmitter noradrenaline

outcomes usually involve an increase in activity

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6
Q

Parasympathetic nervous system

A

Usually causes a decrease in activity

calms the body down

it is the rest and digest system

Parasympathetic neurons release the neurotransmitter acetylcholine

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7
Q

comparison of autonomic and somatic nervous systems

A

SOMATIC:
- single neuron from CNS to effector organ
- heavily myelinated axon
NEUROTRANSMITTER- ACh
EFFECTOR - Skeletal muscle
EFFECT - stimulatory

SYMPATHETIC NERVOUS SYSTEM:
-lightly myelinated preganglionic axons
- Unmyelinated postganglionic axon
NEUROTRANSMITER - NA
EFFECTOR -smooth muscle, glands, cardiac muscle
EFFECT - Stimulatory and inhibitory depending on neurotransmitter and receptors on effector organs

PARASYMPATHETIC NERVOUS SYSTEM:
-lightly myelinated preganglionic axons
- Unmyelinated postganglionic axon
NEUROTRANSMITER - ACh
EFFECTOR -smooth muscle, glands, cardiac muscle
EFFECT - Stimulatory and inhibitory depending on neurotransmitter and receptors on effector organs

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8
Q

Effect of sympathetic nervous system on:
1) Salivary glands
2) Lung
3) Kidney
4) Stomach
5) Small intestine

A

1) Reduced saliva production
2) Bronchial muscles relax
3) Decreased urine secretion
4) Reduced peristalsis
5) reduced peristalsis

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9
Q

Effect of parasympathetic nervous system on:
1) Salivary glands
2) Lung
3) Kidney
4) Stomach
5) Small intestine

A

1) increased saliva production
2) Bronchial muscles contract
3) Increased urine secretion
4) gastric juice secreted
5) Digestion increased

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10
Q

Function of the brain

A

Processes all of the information collected by receptor cells about changes in the internal and external environment

receives and processes information from the hormonal system through molecules in the blood

It then produces a coordinated response

The advantage of having a central control system for the whole body is that communication between neurones is faster

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11
Q

Structure of the brain

A
  • protected by the skull
  • surrounded by protective membranes (meninges)

5 main areas:
- cerebrum
- cerebellum
- medulla oblongata
- Hypothalamus
- Pituitary gland

  • they can be distinguished by their shape, colour or microscopic structure
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12
Q

Cerebrum

A

controls voluntary actions e.g learning, memory, personality and conscious thought

it is highly convoluted which increases its surface area and capacity for complex activity.

Divided into the left and right half (Cerebral hemispheres). Each hemisphere controls one half of the body and has discrete areas which perform specific functions

Cerebral cortex - thin outer layer which is highly folded

Reasoning and decision making occur in the frontal and pre-frontal lobe of the cerebral cortex.

Each sensory area within the cerebral hemisphere receives information from receptor cells in sense organs. the information is then passed on to other areas of the brain (association areas) to be analysed and acted upon.

Primary motor cortex (located at the back of the frontal lobe) controls movement

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13
Q

cerebellum

A

controls unconscious functions e.g posture, balance and non-voluntary movement

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14
Q

Medulla Oblongata

A

Used in autonomic control e.g controls heart rate and breathing rate

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15
Q

Hypothalamus

A

regulatory centre for temperature and water balance

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16
Q

Pituitary gland

A

Stores and releases hormones that regulate many body functions

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17
Q

Stages of a reflex arc

A

Receptor - detects stimulus and creates an action potential in the sensory neurone

Sensory neurone - carries impulse to spinal cord

Relay neurone - connects sensory neurone to motor neurone

Motor neurone - carried impulse to the effector

Effector - carries out the appropriate response

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18
Q

Reflex

A
  • a body responds to a stimulus without conscious thought
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19
Q

Spinal cord structure

A
  • a column of nervous tissue
  • surrounded by thr spine for protection
  • at intervals, neurones emerge
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20
Q

Knee-jerk reflex

A

Spinal reflex - the neural circuit only goes up to the spinal cord

Function - works to quickly straighten your leg if the body detects your quadriceps is suddenly stretched - helps to maintain posture and balance

Process:
- stretch receptors in the quadriceps muscle detect that the muscle is being stretched
- a nerve impulse is passed along a sensory neurone which communicates with a motor neurone in the spinal cord (no relay neurone involved)
- the motor neurone carries the nerve impulse to the effector (extensor muscle) causing it to contract
- at the same time a relay neurone inhibits the motor neurone of the flexor muscle causing it to relax
- lower leg moves forward quickly

21
Q

Blinking reflex

A

Cranial reflex - occurs in the brain not spinal cord

  • sensory nerve endings in the cornea are are stimulated by touch
  • a nerve impulse is sent along the sensory neurone to a relay neurone in the CNS
  • The impulse is passed from a relay neurone n the lower brain stem to a motor neurone
    Motor neurones send impulses to the effectors (orbicularis oculi muscles) which contract causing your eyelids to close quickly
  • consensual response - both eyes are closed in response to the stimulus
22
Q

Survival importance of reflexes

A
  • avoid the body from being harmed/ reduce the severity of any damage

Involuntary response - the decision making regions of the brain aren’t involved so the brain is able to deal with more complex responses

Not having to be learnt - present at burn and provide immediate protection

Fast - the reflex arc is short - only involves 1/2 synapses

Many reflexes are everyday actions e,g digestion, keeping us upright

23
Q

What are the different types of muscle

A

Skeletal

Cardiac

Involuntary

24
Q

Skeletal muscle function and structure

A

Function - responsible for movement

Structure:

Cross striations

Muscles are tubular and multi-nucleated

Conscious control

Regularly arranged so muscle contracts in 1 direction

Rapid contraction speed

Short length of contraction

25
Q

Cardiac muscle function and structure

A

Function - allow the heart to beat in a regular rhythm

Myogenic - contract without the need for a nervous stimulus

Structure:

Specialised striated

Involuntary control

Muscle fibres are connected by intercalated discs which have low electrical resistance so nerve impulses pass easily between cells

Cells branch and interconnect resulting in simultaneous contraction

Intermediate contraction speed and length of contraction

Fibres are branches and uninucleated

26
Q

Involuntary/smooth muscle function and structure

A

Function - found in many parts of the body e,g walls of hollow organs e.g stomach and bladder.
E.g smooth muscles in the gut contract to move food along

Structure:
Non striated

Involuntary

No regular arrangement - different cells can contract in different directions

Slow contraction speed
Long contraction duration

Fibres are spindle shaped and uninucleated

27
Q

Structure of skeletal muscle - muscle fibres

A

Skeletal muscles are made up of bundles of muscle fibres enclosed in a plasma membrane

Sarcolemma- plasma membrane

Contains many nuclei which are longer than normal cells as they are formed as a result of individual embryonic muscle cells fusing together . This makes the muscle stronger as the junction between adjacent cells would act as a point of weakness

Sarcoplasm - shared cytoplasm within a muscle fibre

T tubules - parts of the sarcolemma fold inwards to help spread electrical impulses throughout the sarcoplasm - this ensures the whole fibre receives the impulse to contract at the same time

Lots of mitochondria - provide the ATP for muscle contraction

Sarcoplasmic reticulum - contains the Ca2+ ions for muscle contraction.

28
Q

Myofibrils

A

Long cylindrical organelles made up of protein

specialised for contraction

Lined up in parallel to provide maximum force when they all contract together

Made up of actin and myosin

29
Q

Actin

A

Thinner filament

Consists of 2 strands twisted around eachother

30
Q

Myosin

A

Thicker filament

Long, rod shaped fibres with bulbous heads that project on one side

31
Q

Light bands / I bands

A

Region where actin and myosin filaments don’t overlap

Only contain actin filaments

32
Q

Dark bands / A bands

A
  • dark due to the presence of thick myosin filaments
  • myosin is overlapped with actin
33
Q

Z line

A

Found at the centre of each light band

34
Q

Sarcomere

A

The distance between 2 adjacent Z lines

35
Q

H zone

A

Found at the centre of the dark bands

Only myosin filaments are present

36
Q

M line

A

The middle of each sarcomere

Middle of myosin filaments

37
Q

Sliding filament model

A

Myosin and actin filaments slide over eachother to make the sarcomere contract

Simultaneous contraction of lots of sarcomere causes the myofibrils and muscle fibres contract resulting in enough force to pull on a bone and cause movement

When the muscle relaxed sarcomeres return to original length

During contraction, myosin filaments pull the actin filaments inwards towards the centre of the sarcomere

38
Q

During muscle contraction

A
  • the light band shortens
  • Z lines move closer together
    -sarcomere shortens
  • H zone shortens
  • dark bands stay the same length
39
Q

Structure of myosin

A

Myosin filament - heads of myosin protrude and the tails wrap around eachother to form the filament

Hinged heads - allows them to move back and forwards

Myosin heads contain a binding site for actin and ATP

40
Q

Structure of actin

A

Actin - myosin binding sites - Binding sites for myosin heads.

When a muscle is relaxed, actin-myosin sites are blocked by tropomyosin which is held in place by troponin so myosin can’t bind to actin and the filaments can’t slide past eachother

When a muscle is stimulated to contract, myosin heads form bonds with actin filaments (actin myosin cross bridges), the myosin heads flex, pulling the actin filament along the myosin filament. The myosin detaches from the actin and it’s head returns to its original angle using ATP

41
Q

neuromuscular junction definition

A

Synapses between a motor neurone and muscle cell

There are many neuromuscular junctions to ensure all muscle fibres contract simultaneously

42
Q

Muscle contraction process - neuromuscular junction

A

1) ACTION POTENTIAL TRIGGERS AN INFLUX OF Ca2+ IONS:
- Muscle contraction is triggered when an action potential arrives at a neuromuscular junction
- this stimulates Ca2+ ion channels to open
- Ca2+ diffuses from the synapse to synaptic knob, where they cause vesicles to fuse with the presynaptic membrane
- Ach is released into the synaptic cleft by exocytosis and diffuses across the synapse
- ACh binds to receptors on the post-synaptic membrane opening Na+ channels and resulting in depolarisation

  • ACh is broken down by acetylcholinesterase into choline and ethanoic acid, preventing the muscle being over stimulated
  • choline and ethanoic acid diffuse back into the neurone where they are recombined into ACh using energy from mitochondria
43
Q

Muscle contraction process - sarcoplasm

A
44
Q

.

A
45
Q

Energy supply during muscle contraction - aerobic respiration.

A
46
Q

Energy supply during muscle contraction - anaerobic respiration.

A
47
Q

Energy supply during muscle contraction - creatine phosphate

A
  • stored in muscle
  • ATP is made by phosphorylating ADP - adding a phosphate group taken from creatine phosphate

CP -

48
Q

Why is energy required during muscle contraction

A

For the movement of myosin heads

To enable the sarcoplasmic reticulum to active,y reabsorb Ca2+ ions from the sarcoplasm

49
Q
A

A Level Biology (6 decks)

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