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Physiology > Physiology wk3 > Flashcards

Physiology wk3 Flashcards

1
Q

what are the functions of the nervous system

A
  • Control of internal environment – coordinated with the endocrine system, perceives/responds to internal and external environment
  • Voluntary control of movement
  • Spinal cord reflexes
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2
Q

what are the anatomical divisions of the nervous system

A

CNS - brain/spinal
PNS - neurons outsdie the cns
sesnsory division - afferent fibers transmit impulses from receptors to CNS
motor division - efferent fibers transmit impulses from CNS to effector organs

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3
Q

what input do we get from the sensory nervous system

A
  • Somatic sensory – perceived from receptors (eyes, ears and skin…)
  • Visceral sensory – not consciously perceived from receptors of blood vessels/organs (heart)
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4
Q

what output is there from the motor nervous system

A
  • Somatic motor – conscious/voluntarily controlled (skeletal muscles)
  • Autonomic motor – not voluntary (cardiac muscle, smooth muscle and glands)
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5
Q

what is an axon

A

it is a nerve fiber, it carries electrical messages as action potentials

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6
Q

what is the synapse

A

made up of pre and post, it is the contact point between of one neuron and dendrite of another

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7
Q

how can we increase speed of transmission between axons

A

increase axon diameter
increase myelin sheath
increasing temp

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8
Q

at rest is membrane potential positive or negative

A

it is negative (-5 to -100 volts)

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9
Q

what is resting membrane potential determined by

A

permeability of plasma membrane to ions
difference in ion concentration across the membrane

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10
Q

how is negative potential maintained

A

by the sodium potassium pump, 2 k+ go in and 3 Na go out of the cell to remain negative

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11
Q

what is an action potential

A

occurs when stimuli of sufficient strength depolarizes the cell

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12
Q

how do action potentials increase membrane potential

A

opens Na+ channels and allows them to diffuse into the cell making it more positive

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13
Q

what is repolariztion

A

returning the membrane to its resting potential

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14
Q

how is repolarization caused

A

k+ leaves the cell rapidly
Na+ channels close

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15
Q

what is the all or none law

A

once a nerve impulse is initiated it will travel the length of neuron

has to be large enough

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16
Q

how do neurotransmitters work

A
  • Chemical messengers released from the presynaptic membrane
  • Binds to receptors on postsynaptic membrane
  • Causes depolarization of postsynaptic membrane
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17
Q

what does EPSP stand for

A

Excitatory postsynaptic potentials

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18
Q

what are the two types of neural depolarzation

A
  1. Temporal summation – rapid and repetitive excitation from a single excitatory presynaptic neuron
  2. Spatial summation – summing EPSPs from several different presynaptic neurons
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19
Q

what does IPSP stand for

A

Inhibitory postsynaptic potentials

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20
Q

what do IPSPs do

A
  • Causes hyperpolarization (more negatve resting potential)
  • Neurons with more negative membrane potential resist depolarization
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21
Q

what are joint proprioreceptors made up of

A
  1. Free nerve endings (touch/pressure)
  2. Golgi type receptors (found in joint ligaments)
  3. Pacinian corpuscles (tissues around joints/skin)
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22
Q

what are muscle proprioreceptors made up of

A
  1. Muscle spindles
  2. Golgi tendon organs
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23
Q

what do muscle spindles do

A

respond to change of muscle length and assist the regulation of movement and maintain posture

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24
Q

what are muscle spindles made up off

A
  • Intrafusal fibers – run parallel to normal muscle fibres(extrafusal fibres)
  • Gamma motor neurons – stimulate intrafusal fibres to connect with extrafusal fibres (by alpha motor neuron
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25
Q

what is the stretch reflex

A

stretch on muscle causes reflex contraction (knee-jerk reflex)

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26
Q

what does the golgi tendon organ do

A
  • Monitors force development in muscle – prevents muscle damage during excessive force generation
  • Stimulation results in reflex relaxation of muscle – inhibitory neurons send inhibitory post synaptic potentials (IPSPs) to muscle alpha motor neuron

ability to oppose gto inhibition will be sue to strength gain

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27
Q

where are motor neurons located

A

within the spinal cord, relay messages to skeletal muscle

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28
Q

what is a motor unit

A

motor neuron and all the muscle fibres it innervates

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29
Q

what is the innervation ratio

A

number of muscle fibres are innervated by a single motor neuron
* Low ratio – fine motor control
* High ratio – not fine muscle control

30
Q

what are the types of motor units

A
  1. Type s (slow/type 1)
  2. Type FR (fast, fatigue resistant/type 2a)
  3. Type FF (fast fatigable/type 2x)
31
Q

what are the key components of the brain

A
  • Cerebrum/cerebral cortex – organisation of complex movement, storage of learned experiences and reception of sensory information
  • Cerebellum – implicated in control of movement and integration of sensory information
  • Brainstem – role in cardiorespiratory function, locomotion, muscle tone, receiving information from special senses
32
Q

what makes up the brain stem

A
  • Midbrain – connects the pons and cerebal hemispheres, functions include: controlling responses to sight, eye movement, pupil dilation, body movement and hearing
  • Medulla oblongata – involved in control of autonomic function, relaying signals between brain and spincal cord and coordination of body movements
  • Pons – involved in sleep and the control of autonomic function, relays sensory information between the cerebrum and cerebellum
33
Q

what is spinal tuning

A

intrinsic neural networks (central pattern generators) within a spinal cord that refines voluntary movement after getting messages from higher brain centres

34
Q

what is the withdrawl reflex

A

occurs via reflex arc, where a reflex contraction of skeletal muscles can occur in response to sensory input and is not dependant on activation of higher brain centres

35
Q

control of voluntary movement needs co-ordination of what subcortical areas

A
  1. Motor cortex receives input from variety of brain areas (basal nuclei, cerebellum, thalamus)
  2. Spinal mechanism (spinal tuning) results in refinement of motor control
  3. Feedback from proprioceptors allows for further modification
36
Q

what does the parasympathetic system control

A

resting and digestion

37
Q

what does sympathetic system control

A

fight or flight, regulates blood flow and increases cardiac output

38
Q

what comes under autonomic processes

A

Hr and blood pressure

39
Q

where in the spinal cord does the sympathetic nervous system travel from

A

T1-L2 (thoratic and lumbar region)

40
Q

where in the CNS does the parasympathetic nervous system travel from

A

within the brain stem and sacral region

41
Q

what does cholinergic mean

A

any fiber that secretes acetylcholine

42
Q

what does adrenergic mean

A

any fiber that secretes epinephrine/NE
adrenalin

43
Q

what is different about para/sympathetic nervous system cell bodies hormone release

A

para shoots ach from pre and post ganglionic neurons
symp shoots ach from pre ganglionic but also fires NE and ACH from post ganglionic neurons

44
Q

what is the difference in size of the pre and post ganglionic neurons in the two different systems

A

in para there is longer axons and synapses are closer to the effectors,
in symp there is shorter axons further away from the effectors

45
Q

how does the para system work to reduce HR

A

neurons from the CCC (vagus nerve) release ACH that links to the SA and AV node , this decreases their activity

46
Q

how does the symp system work

A

neurons from the spinal cord act as cardiac accelerators, release NE onto beta receptors on the heart to increase HR

47
Q

what causes initial raise in HR

A

parasypathetic withdrawl and SNS outflow

48
Q

how is stroke volume regulated

A
  1. End-diastolic volume – volume of blood pumped in the ventricles at the end of diastole (preload)
  2. Average aortic blood pressure – pressure the heart must pump against to eject blood, mean arterial pressure (afterload)
  3. Strength of the ventricular contraction (contractility) – enhanced by circulating epinephrine and norepinephrine and direct sympathetic stimulation of heart
49
Q

what does increase in afterload cause

A

lower SV during resting conditions

50
Q

what is frank starlings law

A

increase in venous return leading to improved SV

51
Q

how is venous return increased

A
  • Venoconstriction – via SNS
  • Skeletal muscle pump – contraction squeezes veins forcing blood movement
  • Respiratory pump – changes in thoracic pressure pulls blood towards the heart
52
Q

what is systolic presssure

A

pressure generated during ventricular contraction

53
Q

what is diastolic pressure

A

pressure in arteries in cardiac relaxation

54
Q

what is pulse pressure

A

difference between systolic and diastolic pressure

55
Q

what is mean arterial pressure

A

average pressure in the arteries map = dab + 0.33 (sbp – dbp)

56
Q

formula for MAP

A

cardiac output x total vascular resistance (sum of resistance to blood flow)

57
Q

what are the short term regulators for blood pressure

A
  • Sympathetic nervous system
  • Baroreceptors in aorta and carotid arteries – increase in BP = less SNS activity, decrease in BP = increased SNS activity
58
Q

where in the body controls long term regulation of blood volume

A

the kidney

59
Q

how is increased blood flow to skeletal muscles done

A
  1. Increased cardiac output
  2. A redistribution of blood flow from inactive organs to the working skeletal muscles
60
Q

what do changes in hr and bp depend on

A
  • Type, intensity and duration of exercise
  • Environmental conditions
  • Emotional influence before and during exercise – due to increases in SNS activity
61
Q

how does the body transition from rest to exercise

A

Onset – rapid increase in HR, SV and Q. plateau in submaximal exercise
Recovery – decreased HR, SV and Q. depends on intensity and training type

62
Q

what does recovery of hr and bp between bouts depend upon

A
  • Fitness level
  • Temp and humidity
  • Duration of intensity of exercise
63
Q

what is the cv drift

A

Gradual increase in hr when prolonged exercise due to decreased SV

64
Q

what are the measures of energy expenditure

A
  • Direct calorimetry – measures heat exchange between human body and the environment
  • Indirect calorimetry – measures type and rate of substrate utilization, estimated from gas exchange
  • Doubly labelled water – measures total carbon dioxide production by observing the different rates of elimination of a bolus dose of the stable isotope tracers (hydrogen and oxygen)
65
Q

what does the ANS do

A

maintains homeostasis at rest and in response to changes in physiological state, these changes in homeostasis are achieved through parasympathetic and sympathetic nervous systems.

66
Q

what are the accurate measurements of HR/HRV

A
  • Electrocardiogram (ECG) – criterion measure
    During each heartbeat, the heart depolarizes and repolarizes resulting in electrical charges on the skin.
  • Photoplethysmography (PPG) – reliable and valid
    Properties in skin and tissue are always changing due to blood-flow, by using light emitters towards the skin the photosensor can measure light absorption
67
Q

what is heart rate variability

A

Premise – beat-to-beat variation in the length of cardiac cycles
Interpretation – the greater the HRV, the greater the modulatory influence of the cardiac vagus on heart rate

timing between heart beats

greater hrv = healthier

68
Q

what are the acute stressors

A
  • Hard workout
  • Intercontinental travel
  • Drinking alc
  • Caffeine
69
Q

what are the chronic stressors

A
  • Work/study
  • Infection
  • Illness
70
Q

what does sensitivity mean

A

capacity of an organism or sense organ to respond to stimulation

71
Q

what does reactivity mean

A

the quality or state of being reactive or readily responsive to a stimulus, due to stress

Physiology (13 decks)

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