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Biology Module 5 > Animal responses > Flashcards

Animal responses Flashcards

1
Q

Whats the autonomic nervous system

A

this is part of the nervous system responsible for controlling the involuntary motor activities of the body

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2
Q

Whats the peripheral nervous system

A

the sensory and motor nerves connecting the sensory receptors and effectors to the CNS

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3
Q

Whats the somatic nervous system

A

the motor neurones under conscious control

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4
Q

Whats the central nervous system

A

the central part of the nervous system composed of the brain and spinal cord

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5
Q

describe divisions of the nervous system

A
  • there is the PNS and CNS
    PNS
  • this further divides into the sensory and motor system
  • motor system divides into the somatic nervous system and the autonomic nervous system
    CNS
  • divides into the brain and spinal cord
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6
Q

Describe the CNS

A
  • CNS consists of the brain and spinal cord
  • much of the brain is composed of relay neurones which have multiple connections enabling complex neural pathways - these cells are non-myelinated cells and the tissue looks grey in colour and is known as grey matter
  • spinal cord has many non-myelinated relay neurones making up central grey matter - spinal cord contains large numbers of myelinated neurones making up an outer region of white matter
  • myelinated neurones carry action potentials up and down the spinal cord for rapid communication over longer distances
  • spinal cord is protected by the vertebral column - between each of the vertebrae peripheral nerves enter and leave the spinal cord carrying action potentials to and from the rest of the body
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7
Q

What is the role of the peripheral nervous system

A
  • role of the PNS is to ensure rapid communication between sensory receptors, the CNS and the effectors
  • PNS is composed of sensory and motor neurones which are usually bundled together in connective tissue sheath to form nerves
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8
Q

describe the sensory nervous system

A
  • sensory fibres entering the CNS are dendrons of the sensory neurones
  • neurones conduct action potentials from the sensory receptors into the CNS
  • these neurones have their cell body in the dorsal root leading into the spinal cord and a short axon connecting to other neurones in the CNS
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9
Q

Describe the motor nervous system - The somatic nervous system

A
  • conducts action potentials from the CNS to the effectors
  • the somatic nervous system - consists of motor neurones that conduct action potentials from the CNS to the effectors that are under voluntary control such as the skeletal muscles, these neurones are mostly myelinated so that response can be rapid - always one single motor neurone connecting the CNS to the effector
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10
Q

Describe the motor nervous system - The autonomic nervous system

A
  • the autonomic nervous system - consists of motor neurones that conduct the action potentials from the CNS to effectors that are not under voluntary control this includes the glands, cardiac muscle and smooth muscle in the walls of the blood vessels, the airways and the wall of the digestive system
  • the control of many of these effectors does not require rapid responses and the neurones are mostly non-myelinated
  • there are at least two neurones involved in the connection between the CNS and the effector - they are connected at small swellings called ganglia
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11
Q

what can the autonomic system be divided in to

A
  • sympathetic system and the parasympathetic system
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12
Q

Describe differences between the sympathetic system and the parasympathetic system

A

sympathetic system
- prepares body for activity
- antagonistic to the parasympathetic system
parasympathetic system
- conserves energy
- antagonistic to the sympathetic system
how they are similar
- action potential passes along at low frequency
- controlled by subconscious parts of the brain
- changes in internal conditions or stress lead to changes in the balance of stimulation between the two systems and this leads to an appropriate response

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13
Q

describe the role of the sympathetic system

A
  • consists of many nerves leading out of the CNS
  • ganglia just outside the CNS
  • short pre-ganglionic neurones
  • long post-ganglionic neurones
  • uses noradrenaline as the neurotransmitter
  • increases activity
  • most active at times of stress
  • effects include : increases heart rate, dilutes pupils, increases ventilation rate, reduces digestive activity, orgasm
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14
Q

describe the role of the parasympathetic system

A
  • consists of a few nerves leading out of the CNS which divide up and lead to different effectors
  • ganglia in the effector tissue
  • long pre-ganglionic neurones
  • short post-ganglionic neurones
  • uses acetylcholine as the neurotransmitter
  • decreases activity
  • most active during relaxation
  • effects include - decrease heart rate, constricts pupils, reduces ventilation rate, increases digestive activity, sexual arousal
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15
Q

What are the four main parts of the brain

A
  • cerebrum
  • cerebellum
  • hypothalamus and pituitary complex
  • medulla oblongata
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16
Q

Describe the role of them cerebrum

A

largest part and organises most of our higher thought processes such as conscious thought and memory

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17
Q

Describe the role of the cerebellum

A

coordinates movement and balance

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18
Q

Describe the role of the hypothalamus and pituitary complex

A

organises homeostatic responses and controls various physiological processes

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19
Q

Describe the role of the medulla oblongata

A

coordinates many autonomic responses

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20
Q

Describe the structure of the cerebrum

A
  • 2 cerebral hemispheres that are connected by major tracts of neurones called the corpus callosum
  • outermost layer of the cerebrum consists of a thin layer of nerve cell bodies called the cerebral cortex

Divided into areas:

  • sensory areas
  • association areas
  • motor areas
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21
Q

what higher order brain functions does the cerebrum control

A
  • conscious thought
  • conscious action
  • emotional responses
  • intelligence, reasoning, judgement and decision making
  • factual memory
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22
Q

what does the sensory area do in the cerebrum

A
  • receive action potentials indirectly from the sensory receptors
  • size and regions allocated to receive input from different receptors are related to the sensitivity of the area that inputs are received from
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23
Q

What does the association area do in the cerebrum

A
  • compare sensory inputs with previous experience, interpret what the input mean and judge and appropriate response
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24
Q

What does the motor area do in the cerebrum

A
  • send action potentials to various effectors
  • sizes of the regions allocated to deal with different effectors are related to the complexity of the movements needed in the parts of the body
  • motor areas of the left side of the brain control the effectors on the right and vis versa
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25
Q

Describe the structure of the cerebellum

A
  • contains over half of all of the neurones in the brain
  • involved with balance and fine coordination of movement
  • it must receive information from many sensory receptors and process the information accurately
  • sensory receptors that supply infomration to the cerebellum include the retina, the balance organs in the inner ear and spindle fibres in the muscle which give information about the muscle length and the joints
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26
Q

Describes jobs of the cerebellum

A
  • maintaining body position and balance
  • judging the position of objects and limbs while moving about or playing sport
  • tensioning muscles in order to use tools and play musical instruments effectively
  • coordinating contraction and relaxation of antagonisitc skeletal muscles when walking and running
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27
Q

Describe how the cerebellum does the jobs that it does

A
  • control often requires learning
  • once learnt they become second nature and involve much unconscious control
  • this sort of coordination requires complex nervous pathways and these are strengthened by practise
  • they become programmed into the cerebellum and neurones from the cerebellum conduct action potentials to the motor area so that motor output to the effectors are controlled
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28
Q

Describe the hypothalamus

A
  • temperature - detects temperature changes in core body temperature, also receives sensory input from temperature receptors in the skin, it will initiate responses to temperature change that regulate body temperature within a narrow range - mediated by the nervous system or by the hormonal system
  • osmoregulation - hypothalamus contains osmoreceptors that monitor the water potential in the blood - when the water potential changes the osmoregulatory centre initiates responses that bring about a reversal of this change - these are mediated by the hormonal system
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29
Q

Describe the pituitary gland

A
  • linked to the hypothalamus by specialised neurosecretory cells, hormones such as ADH are manfuactured in the hypothalamus and are passed down the neurosecretory cells and released into the blood from the pituitary gland
  • anterior lobe produces its own hormones which are released into the blood in response to releasing factors produced by the hypothamalus
  • these releasing factors are hormones that need to be transported only a short distance from the hypothamalus to the pituitary
  • hormones from the anterior pituitary control a number of physiological processes in the body including response to stress, growth and lactation
30
Q

Describe the medulla oblongata

A
  • controls the non-skeletal muscles by sending action potentials out through the autonomic nervous systme
  • the medulla oblongata contains centres for regulating several vital processes including:
  • the cardiac centre which regulates heart rate
  • the vasomotor centre - regulates circulation and blood pressure
  • the respiratory centre - controls rate and depth of breathing
  • coordinates responses by negative feedback
31
Q

What is a reflex action

A
  • reflex action is a response that does not involve any processing in the brain
32
Q

Describe a reflex action

A

sensory neurone - relay neurone - motor neurone

33
Q

What is a reflex action mainly used for

A
  • for survival, used to get out of danger and prevent damage to the body
  • used to maintain balance
  • short as possible in order to get the quickest response
34
Q

Whats the blinking reflex stimulated by

A
  • a foreign object touching the eye
  • a sudden bright light
  • loud sounds
  • sudden movement close to the eye
35
Q

describe the nervous pathway for the blinking reflex

A
  • passes through part of the brain therefore it is a cranial reflex
  • pathway is a direct pathway that does not involve thought processes in the higher parts of the brain since the receptor and the effector are in the same place this is called a reflex arc
36
Q

Describe the corneal reflex works

A
  • mediated by sensory neurone from the cornea which enters the pons
  • synapse connects the sensory neurone to a relay neurone which passes the action potential to a motor neurone
  • motor neurone passes out of the brain to muscles in the face causing the eyelid blink - this is a short and direct pathway so the corneal reflex is rapid
  • causes both eyes to blink
37
Q

Where else is the action potential passed during the corneal reflex

A
  • sensory neurone involved passes the action potential to myelinated neurones in the pons
  • myelinated neurones carry the action potential to the sensory region in the cerebral cortex to inform the higher centres that this reflex action has occurred
  • allows reflex to be overridden by conscious control
  • higher parts send inhibitory signals to the motor centre in the pons and the myelinated neurones can send signals faster than the non myelinated neurones therefore the inhibitory action potentials can prevent the formation of an action potential in the motor neurone and the reflex action from happening
38
Q

describe knee jerk reflex

A
  • spinal reflex
  • only consists of two neurones - sensory neurone and motor neuorne
  • one less synpase is involved making it quicker
  • other reflex actions the higher parts of the brain are informed that it is occuring but there is no relay neurone therefore the brain cannot inhibit the action
  • in absence of relay neurone the motor neurone is directly stimulated by the sensory neurone and there is insufficent delay to enable inhibition therefore docotrs test your reflexes by tapping the tendon below the knee cap
39
Q

Describe how walking works (Knee jerk reflex)

A
  • knee must bend and this stimulates muscle spindles
  • complex pattern of nervous impulses coming from the cerebellum is able to inhibit the reflex contractions
  • action potentials are sent to the thigh stimulating it to contract but inhibitory action potentials are sent to the synapse in the reflex arc to prevent the reflex contraction of the opposing muscle
40
Q

Describe what the knee jerk reflex job is

A
  • coordinated movement
  • balance
  • muscle at the front of the left contracts to straighten the leg and the muscle attached to the lower leg via the patella tendon that connects the patella to the lower leg bones at the front of the knee
  • when the muscles at the front of the thigh are stretched, specialised stretch receptors called muscle spindles detect the increase in length of the muscle and as this is unexpected a reflex action causes contraction of the same muscle
41
Q

Describe what the knee jerk reflex job is

A
  • coordinated movement
  • balance
  • muscle at the front of the left contracts to straighten the leg and the muscle attached to the lower leg via the patella tendon that connects the patella to the lower leg bones at the front of the knee
  • when the muscles at the front of the thigh are stretched, specialised stretch receptors called muscle spindles detect the increase in length of the muscle and as this is unexpected a reflex action causes contraction of the same muscle
  • part of the mechanism that enables us to balance on two legs
  • contraction straightens the knee and brings the body back above the legs
42
Q

responses may be

A

short term or long term

43
Q

How does the brain coordinate responses through output to the effectors, this output may include

A
  • action potentials in the somatic nervous system
  • action potentials in the sympathetic and parasympathetic parts of the autonomic nervous system
  • release of hormones via the hypothalamus and pituitary gland
44
Q

What is the flight and fight response

A
  • leads to physiological changes that prepare the animal for activity - may be running away or direct challenge to a perceived threat
45
Q

Physiological change and survival value:

  • Pupils dilate
  • heart rate and blood pressure increase -
  • arteriole to the digestive system are constricted whilst those to the muscle and liver are dilated
  • blood glucose levels increase
  • metabolic rate increases
  • erector pili muscles in the skin contract
  • ventilation rate and depth increase
  • endorphins are released into the brain
A
  • allows more light to enter the eyes, making the retina more sensitive
  • increases the rate of blood flow to deliver more oxygen and glucose to the muscles and to remove carbon dioxide and other toxins
  • diverts blood flow away from the skin and digestive system towards the msucles
  • supplies energy for muscular contraction
  • converts glucose to useable forms of energy such as ATP
  • makes hair stands up
  • increases gaseous exchange so that more oxygen enters the blood and supplies aerobic respiration
  • wounds inflicted on the mammal do not prevent activity
46
Q

Describe the coordination of the flight or fight response

A
  • receptor can detect an external threat including the eys and nose
  • internal receptors may detect a threat such as pain or a sudden increase or decrease in blood pressure
    1. inputs feed into the sensory centres in the cerebrum
    2. cerebrum passes signals to the association centres
    3. if a threat is recognised the cerebrum stimulates the hypothalamus
    4. the hypothalamus increases activity of the sympathetic nervous system and stimulates the release of hormones form the anteriror pituitary gland
47
Q

What is the role of the sympathetic nervous system in coordinating responses

A
  • autonomic nervous system controls many of the physiological mechansism
  • increasing the stimulation of the sympathetic nervous system will increase the activity f the effectors
  • nervous communication is used for rapid response rather than prolonged response
  • fight or flight from danger may need a prolonged response and this is achieved by the endocrine system
  • sympathetic nervous system stimulates the adrenal medulla, adrenaline released from the adrenal medulla has a wide range of effects on cells
48
Q

Describe how adrenaline works

A
  1. adrenaline binds to the adrenaline receptor on the plasma membrane, the receptor is associated with a G protein on the inner surface of the plasma membrane, this is stimulated to activate the enzyme adenyl cyclase
  2. adenyl cyclase converts ATP to cyclic AMP which is the second messenger inside the cell
  3. cAMP causes an effect inside the cell by activating enzyme action
49
Q

the hormones released from the pituitary gland are

A

CRH

TRH

50
Q

the hypothalamuis secretes releasing hormones and what do they do

A
  • also known as releasing factors
  • they go into the blood pass down a portal vessel to the pituitary gland and stimulate the release of tropic hormones from the anteriror part of the pituitary gland
51
Q

What does CRH do

A
  • causes the release of ACTH
  • ACTH is passed around the blood system and stimulates the adreneal cortex to release a number of different hormones
  • these include glucocorticoids such as cortisol whcih regulate the metabolism of carbohydrates therefore more glucose is released from glycogen stores
  • new glucose may also be produced from fat and protein stores
52
Q

What does TRH do

A
  • causes the release of TSH
  • stimulates thyroid gland to release more thyroid hormones
    = thyroxine acts of nearly every cell of the body increasing the metabolic rate and making cells more sensitive to adrenaline
53
Q

What are the three types of muscle

A
  • cardiac muscle
  • involuntary (smooth muscle)
  • voluntary (skeletal or striated) muscle
54
Q

Describe involuntary muscle (smooth)

A
  • consist of individual cells tapered at both ends
  • each cell is 500 micrometres long and 5 micrometres wide
  • contains a nucleus and bundles of myosin and actin
  • found in the walls of tubular structures such as the digestive system and blood vessels
  • muscle is usually arranged in longitudinal and circular layers that oppose each other
55
Q

Describe cardiac muslce

A
  • formed in the muscular part of the heart
  • individual cells form long fibres which branch to form cross-bridges between the fibres these help ensure that electrical stimulation spreads evenly over the walls of the chambers
  • when the muscle contracts this arrangement also ensures that the contraction is a squeexing action rather than 1 dimensional
  • cells are joined by intercalated discs, these are specialsied cell surface membranes fused to produce gap juctions these allow free diffusion of ions between the cells
  • action potentials pass easily and quickly along and between the cardiac muscle fibres
  • cardiac muscle contracts and relaxes continuously throughout its life
  • contract powerfully an does not fatigue easily
  • myogenic
  • some muscle fibres in the heart such as purkyne fibres can carry electrical impulses
  • rate of contraction is usually controlled by SAN
56
Q

Describe voluntary muscle (striated or skeletal)

A
  • occurs at the joints in the skeleton
  • contraction causes movement of the skeleton by bending of straightening the joint
  • form fibres of about 100 micrometres in diameter, each fibre is multinucleate and is surrounded by a membrane called the sarcolemma
  • muscle cytoplasm is known as sarcoplasm and is specialised to contain many mitochondria and an extensive sacropplasmic reticulum
  • arranged into myofibrils which are contractive elements
  • myofibrils are divided into a chain of subunits called sarcomeres
  • sarcomeres contain the protein filaments actin and myosin
  • actin and myosin are arranged in a particular banded pattern which gives the muscle a striped or striated appearence
  • dark bands = A bands
  • light bands = I bands
57
Q

What is the neuromuscular junction

A
  • skeletal muscle is under voluntary control
  • contractions are stimulated by the somatic nervous system
  • junction between the nervous system and the muscle is called the neuromuscular juction
58
Q

Describe the stimulation of contraction

A
  1. action potentials arrive at the end of the axon
  2. open calcium channel
  3. calcium ions flood in
    4, vesciles of acetylcholine move towards and fuse with the end membrane
  4. acetylcholine molecules diffuse across the gap and fuse with receptors in sarcolemma
  5. opens sodium ion channels allowing sodium ions to enter the muscle fibre
  6. depolarisation of the sarcolemma
  7. spreads down transverse tubules into the muscle fibre
59
Q

What is a motor unit

A
  • some motor neurones divide and connect to several muscle fibres, all thee muscle fibres contract together providing a stronger contraction - this is called a motor unit
60
Q

What is a myofibril

A
  • these are the contractile units of skeletal muscle and contain two types of muscle filament
61
Q

What are the filaments in the myofibril

A
  • thin filaments - these are actin and are aligned to make up the light band, they are held together by the Z line
  • thick filaments - these make up the dark band, and are myosin
62
Q

What is the area called where the thick and thin filaments do not overlap

A
  • the H zone
63
Q

what is the distance between 2 Z lines called

A
  • distance between two Z lines is called a sarcomere

- it is about 2.5 micrometres long

64
Q

What are the thick and thin filaments surrounded by

A
  • surrounded by a sacroplasmic reticulum
65
Q

Describe the thin filaments

A
  • made of actin
  • each filament consists of two chains of actin subunits twisted around each other
  • wound around the actin is a molecule of tropomyosin to which are attached globular molecules of troponin
  • each troponin complex has three polypeptides - one binds to actin, one to tropomyosin and one to calcium when it is available
  • tropomyosin and troponin are part of the mechanism to control muscular contraction
  • at rest the molecules cover binding sites to which the thick filaments can bind
66
Q

Describe the thick filaments

A
  • bundle of myosin
  • two protruding heads which stick out at each end of the molecule
  • these heads are mobile and can bind to the actin when the binding sites are exposed
67
Q

describe the sacromere when it is contracted

A
  • light band and H zone get shorter
  • Z lines move closer together
  • Sacromere gets shorter
68
Q

Describe the sliding filament hypothesis

A
  • caused by the movement of myosin heads
    1. when the muscle is stimulated the action potential passes along the sacrolemma and down the transverse tubules into the muscle fibre
    2. the action potential is carried to teh sarcoplasmic reticulum which stores calcium ions into the sarcoplasm
    3. the calcium ions bind to the troponin which alters the shape pulling the tropomyosin aside, exposing the binding sites on the actin
    4. myosin heads bind to the actin forming cross-bridges between the filaments
    5. the myosin heads move pulling the actin filament past the myosin filament
    6. the myosin heads detach from the actin and can bind again further up the actin filament
69
Q

Describe the role of ATP

A
  • ATP supplies energy for contraction, part of the myosin head acts as ATPase and can hydrolyse the ATP to ADP and inorganic phosphate releasing energy
    1. The myosin head attaches to the actin filament forming a cross bridge
    2. the myosin head moves cuasing the thin filament to slide past the myosin filament, this is the power stroke and during the power stroke ADP and Pi are released from the myosin head
    3. after the power stroke a new ATP molecule attaches to the myosin head breaking the cross-bridge
    4. the Myosin head then returns to its original position as the ATP is hydrolysed, releasing energy to make the movement occur
    5. myosin head can make a new cross-bridge
70
Q

describe how you have to maintain the supply of ATP

A
  1. aerobic respiration in mitochondria - muscle tissues contains a large number of mitochondria in whcih aerobic respiration can occur - bohr effect releases more oxygen from the haemoflobin in the blood, rate limited by the amount of oxygen delivered to muscle
  2. anaerobic respiration in sarcoplasm - releases a little more ATP but produces lactic acid which is toxic, anaerobic respriation can only last a few seconds before lactic acid buuild up starts to cause fatigue
  3. Creatine phosphate in sarcoplasm - sarcoplasm acts as a reserve store of phosphate groups, the phosphate groups can be transferred from the creatine phosphate to ADP molecules creating ATP molecules very rapidly, the ezyme creatine phosphotransferase is involved, it can support muscle contraction for another 2-4 seconds

Biology Module 5 (12 decks)

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