7.3 Peak performance Flashcards

1
Q

When exercising adequate O2 supply is maintained by:

A
  • increasing cardia output
  • faster rate of breathing
  • deeper breathing
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2
Q

Aerobic capacity

A

The ability to take in, transport
and use oxygen. Our aerobic capacity
determines our ability to undertake long periods
of vigorous exercise such as running steadily.

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3
Q

O2, V̇O2(max)

A

The volume of oxygen a person
consumes per minute. V̇O2(max) is the volume
of oxygen a person consumes per minute at their
maximum rate of aerobic exercise. V̇ O2(max)
depends on the efficiency with which the lungs
and cardiovascular system take up and deliver
oxygen, and the efficiency with which muscles
use oxygen.

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4
Q

Cardiac output

A

The total volume of blood
pumped out of the left ventricle of the heart in
one minute. The cardiac output depends on the
volume of blood pumped out each time the heart
beats (the stroke volume) and the heart rate.
The relationship between cardiac output, stroke volume and heart rate is given by the equation:
cardiac output = stroke volume × heart rate.

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5
Q

Stroke volume

A

The volume of blood pumped out
of the left ventricle each time the ventricle
contracts. The total amount of blood pumped out
of the heart in one minute is the cardiac output.
The relationship between cardiac output, stroke
volume and heart rate is given by the equation:
cardiac output = stroke volume × heart rate.

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6
Q

Heart rate

A

The number of times the heart beats
per minute. Heart rate varies. Differences in
heart rate are caused by many factors and are
controlled by the cardiovascular control centre
in the brain. The total amount of blood pumped
out of the heart in one minute is the cardiac
output. The relationship between cardiac output,
stroke volume and heart rate is given by the
equation: cardiac output = stroke volume × heart
rate.

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7
Q

Venous return

A

The blood returning to the atria of
the heart along the veins. The increase in muscle
action during exercise increases the venous
return. This results in more blood entering the
atria and more forceful contractions of the
ventricle, increasing stroke volume.

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8
Q

Myogenic

A

Muscle which is able to contract
without being stimulated to do so by a nerve.
Heart muscle is myogenic; the sinoatrial node,
a group of specialised muscle fibres within the
heart wall, initiates the heartbeat.

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9
Q

Sinoatrial node, Pacemaker, SAN

A

A small area
of specialised muscle tissue in the wall of the
right atrium of the heart. It generates electrical
impulses. These spread across the surface of the
atria causing them to contract at the same time.
The sinoatrial node is also called the pacemaker.

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10
Q

Impulse, Nerve impulse

A

A wave of electrical
activity which passes along a nerve or over the
surface of a muscle.

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11
Q

Atrioventricular node, AVN

A

A small area of
specialised tissue in the wall of the heart
between the atria and the ventricles. It plays an
important part in coordinating the heartbeat. The
electrical impulse, which spreads over the
surface of the atria from the sinoatrial node, is
delayed briefly here before continuing to the
ventricles. This ensures that the atria have
emptied and ventricles have filled with blood
before they start contracting.

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12
Q

Purkyne fibres

A

A group of specialised muscle
fibres which run between the right and left
ventricles of the heart. They conduct the
electrical impulses which cause the ventricle
muscle to contract.

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13
Q

Bundle of His

A

Specialised fibres of heart muscle
that go from the atrioventricular node to the tip
of the ventricles. They rapidly carry the
electrical impulse that controls the heartbeat to
the tip of the ventricles. This means that when
the ventricles start to contract, they squeeze the
blood upwards and out through the arteries to
the lungs and the rest of the body.

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14
Q

Bradycardia

A

A heart rate of less than 60 ppm.

possible causes include: hypothermia, heart disease, use of medicines or drugs, fit athlete

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15
Q

Tachycardia

A

A heart rate greater than 100bpm
causes: anxiety, fear, fever, exercise, symptom of heart disease, heart failure, use of medicines or drugs, fluid loss, anaemia

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16
Q

Electrocardiogram

A

A graphic record of the
electrical activity of the heart as it contracts and
rests.

17
Q

Polarisation

A

The formation of an uneven
distribution of ions across a cell surface
membrane making the outside of the membrane
positive and the inside negative.

18
Q

P wave

A
Depolarisation of the atria that leads to
atrial contraction (atrial systole).
19
Q

PR interval

A

The time taken for electrical
impulses in the heart to be conducted from the
sinoatrial node across the atria to the
ventricles, through the atrioventricular node.

20
Q

QRS complex

A

The wave of depolarisation that
results in contraction of the ventricles
(ventricular systole).

21
Q

T wave

A

Repolarisation (recovery) of the
ventricles during the heart’s relaxation phase
(diastole).

22
Q

Cardiovascular control centre

A

An area situated
in the brain which is responsible for controlling
the heart rate. The cardiovascular control centre
receives stimuli resulting from the accumulation
of carbon dioxide and lactate in the blood. It sends impulses
via branches of the autonomic nervous system
to the sinoatrial node in the heart, causing the
heart rate either to slow down or to speed up.

23
Q

Autonomic nervous system

A

The part of the
nervous system that is not under conscious
control. The nerves of the autonomic nervous
system stimulate muscles and glands. The
autonomic nervous system is made of up of two
parts. The sympathetic system plays an
important part in controlling the body’s reactions
to stress. The parasympathetic is more
important when the body is at rest. The somatic
nervous system is under conscious control.

24
Q

Sympathetic nerve

A

One of the nerves that goes
from the brain to the organs of the body and
which prepares the body for action, controlling
the functions of organs during times of stress.
For example, sympathetic nerves are involved in
increasing heart rate and blood pressure.

25
Vagus nerve
The vagus nerve is a parasympathetic nerve. It leads from the cardiovascular control centre in the brain to the sinoatrial node in the heart. Nerve impulses passing along this nerve slow the heart beat
26
Parasympathetic nervous system, | Parasympathetic nerve
The part of the autonomic nervous system (the nervous system which you have no control over) that is important when the body is at rest. Stimulation of the parasympathetic nerves reduces heart and breathing rate but increases muscle action associated with digestion. The vagus nerve is a parasympathetic nerve. It leads from the cardiovascular control centre in the brain to the sinoatrial node in the heart. Nerve impulses passing along this nerve slow the heart beat.
27
Negative feedback
Many substances and systems in living organisms have a set level. This is true of the concentration of glucose in the blood and of body temperature. Negative feedback is the process whereby a departure from this set level sets in motion changes which return it to the original level.
28
Adrenaline
A hormone produced by the adrenal glands at times of stress such as when we are angry or frightened. It has a range of effects on the body. These include increasing the stroke volume and rate of beating of the heart, dilating blood vessels supplying muscles, and stimulating the conversion of glycogen to glucose. Scientists have shown that there are links between stress, adrenaline and an increased risk of heart disease.
29
Tidal volume
Tidal volume is the average volume of one breath. Multiplying the tidal volume by the breathing rate gives the volume of air taken into the lungs in one minute, the minute ventilation. Minute ventilation is calculated from tidal volume and breathing rate using the equation: minute ventilation = tidal volume × breathing rate.
30
Vital capacity
The maximum volume of air a | person can inhale and exhale.
31
Medulla oblongata
Part of the hindbrain or brain stem which is responsible for controlling body processes that we do not consciously have to control. These include heart rate, breathing and blood pressure.
32
Minute ventilation
The volume of air taken into the lungs in one minute. Minute ventilation is calculated from tidal volume and breathing rate using the equation: minute ventilation = tidal volume × breathing rate.
33
Slow twitch fibre
A muscle fibre that produces slow, sustained contractions. The long periods of exercise of which they are capable necessitates respiring aerobically. Associated with this, they have a large number of mitochondria and also contain a lot of the pigment myoglobin. These features give them their distinctive dark red colour.
34
Myoglobin
An oxygen-storing pigment found in the muscle of many animals. It is saturated with oxygen at relatively low oxygen concentrations (low partial pressures) and is able to hold onto this oxygen, only releasing it when the amount of oxygen in the surroundings falls to a very low level. Slow twitch fibres are muscle fibres which contain a lot of myoglobin. This results in their dark red colour.
35
Fast twitch fibre
A muscle fibre that produces rapid powerful contractions. Fast twitch fibres have few mitochondria and little myoglobin. This makes them light-coloured in appearance. Contraction of fast twitch fibres relies on anaerobic respiration and therefore results in a rapid build-up of lactate and a correspondingly rapid onset of fatigue.