Topic 2 Flashcards
Outline the functions of the conducting airways
Low resistance pathway for airflow
Defense against chemicals and other harmful substances that are inhaled
Warming and moistening the air
Nose: Humidifies the air entering and filters particles (thanks to the Vibrissae).
Pharynx: Air then passes through the 3 parts of the pharynx which offers a low resistance path for airflow into the larynx and then finally into the trachea.
Larynx: In addition to its function as the ‘voice box’ it also protects the trachea from invasion of foods and fluids.
Pulmonary ventilation
inflow and outflow of air between the atmosphere and the lungs
Total lung capacity
volume of air in the lungs after a maximum inhalation. The sum of the Vital capacity and residual volume.
Tidal volume
Volume of air breathed in and out in any one breath
Expiratory reserve volume
volume of air in excess of tidal volume that can be exhaled forcefully
Inspiratory reserve volume
additional inspired air over and above tidal volume
Residual volume
volume of air still contained in the lungs after a maximal exhalation
Vital capacity
Maximum volume of air that can be exhaled after a maximum inhalation
Mechanics of ventilation
Air flows because of pressure differences between the atmosphere and gases inside the lungs.
During inhalation the intercostal muscles (between the ribs) and diaphragm contract to expand the chest cavity.
The diaphragm flattens and moves downwards and the intercostal muscles move the rib cage upwards and out. - This increases the space for the lungs.
This increase in size decreases the internal air pressure and so air from the outside (at a now higher pressure than inside the thorax) rushes into the lungs to equalize the pressures.When we exhale the diaphragm and intercostal muscles relax and return to their resting positions. This reduces the size of the thoracic cavity, thereby increasing the pressure and forcing air out of the lungs.
Why do ventilation rates increase
breathing rate increases during exercise as the expiratory centre sends impulses to the expiratory muscles (internal intercostals) which speeds up the expiratory process;
increase CO2 causes the acidity of the blood to increase (decrease blood pH)/a change in acidity of the blood is detected by chemoreceptors which send nerve impulses to the respiratory muscles which increase the rate of ventilation (faster/deeper);
Outline the role of haemoglobin in oxygen transport
98.5% of oxygen in the blood is transported by hemoglobin as oxyhemoglobin within the red blood cells
Hemoglobin is the protein that allows oxygen to bind to a red blood cell. Hemoglobin contains a central Iron ion which can hold up to 4 oxygen atoms per heme. These oxygen atoms are then diffused into the tissues once they reach their target. While they are diffusing they are also picking back up CO2 & returning it back to lungs so you can exhale it into the atmosphere.
Explain the process of gaseous exchange at the alveoli
Gas exchange is carried out by a complex of structures at the end of each bronchioles.
The oxygen exchange in the lungs takes place across the membranes of small balloon-like structures called alveoli attached to the branches of the bronchial passages.
These alveoli inflate and deflate with inhalation and exhalation. The elasticrecoil of these helps in the exhalation. Gases move by diffusion from where they have a high concentration to where they have a low concentration:
The alveoli create a pressure gradient.
Once the alveoli fill up with air during inhalation the oxygen diffuses from the air in the alveoli and into the blood.
The carbon dioxide diffuses from the arriving venous blood and into the air which exits the body during exhalation.
State the composition of blood
Blood is composed of cells (erythrocytes, leucocytes and platelets) and plasma. Blood is the transport vehicle for electrolytes, proteins, gases, nutrients, waste products and hormones.
- Transports nutrients, oxygen, carbon dioxide, waste products and hormones to cells and organs around the body.
- Protects us from bleeding to death, via clotting, and from disease, by destroying invasive micro-organisms and toxic substances.
- Acts as a regulator of temperature, the water content in cells, and body pH.
erythrocytes
Make up 40-45% of the blood volume known as hematocrit. Contain an oxygen-carrying pigment called haemoglobin, which gives blood its red color.
Leucocytes
White blood cells <1% of blood volume, primarily involved in immune fuction and protecting body from infection. They do this by ingesting foreign microbes in a process called phagocytosis.
Platelets
<1% of blood volume. Assist in the provess of repair following an injurt
Autonomic Nervous System
- what does it control
- what does it comprise of
- what controls the two systems
- control of involuntary or visceral bodily functions.
- comprises of the sympathetic system and the parasympathetic system.
- The sympathetic system stimulates the heart to beat faster.
- The parasympathetic system returns the heart to its resting rate.
- The cardiac control centre controls these two systems. -The cardiac control system is located in the medulla oblongata of the brain.
Sympathetic Nervous System
- what does it stimulate
- which receptors are stimulated
- what do the receptors do
Sympathetic system stimulates the heart to beat faster; due to multiple factors. During exercise, 3 receptors are stimulated; proprioceptors, baroreceptors, chemoreceptors. The receptors send impulses (action potentials) to the cardiac control centre (medulla oblongata), which then sends an impulse through the sympathetic nervous system to stimulate the SA node of the heart where the heart rate increases.
Parasympathetic Nervous System
-what happens when exercise stops?
When exercise stops, the receptors pick up decreases in co2 levels, blood pressure and muscle movement; hence impulses are sent to the cardiac control centre (medulla oblongata). An impulse is sent to the parasympathetic nervous system which stimulates the SA node and heart rate decreases.
Hormonal control
- 2 stress hormones
- released from?
- exercise causes an?
- which results in? (SA node, blood pressure, blood glucose)
Adrenaline and noradrenaline are stress hormones
Released by adrenal glands
Exercise causes stress induced adrenaline response which results in:
Stimulation of SA node, which results in increased speed and force of contraction.
Increase in blood pressure due to constriction of blood vessels.
Increase in blood glucose levels (glucose is used by muscles for energy)
Pulmonary circulation
*portion of the cardiovascular system that carries oxygen-depleted blood AWAY from the heart and TO the lungs and then RETURNS it, oxygenated, back to the heart.
Systematic circulation
is the portion of the cardiovascular system that carries the oxygenated blood away from the heart and delivers it to the body. It also carries the deoxygenated blood after use back to the heart to be re-oxygenated.
Describe the relationship between heart rate, cardiac output and stroke volume at rest and during exercise
cardiac output = stroke volume x heart rate
Stroke volume for different populations
increases according to how you exercise because your body needs more oxygen and nourishment, which are both received from the blood.
increases depending on the type of physical activity your are doing and your training level.
during an upright physical activity like jogging, stroke volume increases from about 50 mL at rest to 120 mL at maximal exercise intensity.
In a trained Olympic runner, stroke volume can increase from 80 mL at rest to 200 mL during maximal exercise intensity as the heart pumps more efficiently.
Cardiac output for different populations
because stroke volume increases, cardiac output increases simultaniously with the increase in heart rate and the body beings to work harder
Explain causes cardiovascular drift
*refers to the increase in heart rate that occurs during prolonged endurance exercise with little or no change in workload.
An increase of body temperature results in a lower venous return to the heart, a small decrease in blood volume from sweating. A reduction in stroke volume causes the heart rate to increase to maintain cardiac output.
Blood viscosity, if the blood is thinker and more viscous, it makes it more difficult to be returned back (up gravity) to the heart to pick up more oxygen.
systolic blood pressure
the force exerted by the blood on the arterial walls during ventricular contraction
diastolic blood pressure
the force exerted by the blood on the arterial walls during ventricular relaxation
Discuss how systolic and diastolic blood pressure respond to static and dynamic exercise
Although blood pressure goes up during any kind of exercise, the exact changes (figures) are different according to whether the exercise is static or dynamic.
Static (isometric) exercise
-definition
- why does systolic blood pressure increase?
- why does diastolic blood pressure increase?
-what happens to breathing during static exercise?
defined as a sustained contraction of a muscle group where the muscle is contracted but there is no change in muscle length: eg weight lifting, yoga
Why does Systolic blood pressure increase?
Volume of blood + contraction rate a larger amount of blood is being pumped through the arteries with each contraction;
Why does Diastolic blood pressure increase?
The pressure on the arterial walls is increased even during relaxation
The vasoconstriction creates an increase in pressure
Muscles squeeze the veins to promote venous return, by doing so increases pressure
During static exercise, breathing is more constricted, there is less oxygen and more carbon dioxide, the heart must work harder to pump the blood it does have to supply the muscles with sufficient oxygen to continue the static exercise
Dynamic exercise
- why does systolic blood pressure increase at a lower rate?
- why does diastolic blood pressure remain the same?
Why does Systolic blood pressure increase at a lower rate?
the breathing frequency is much higher than in static exercise, therefore the pressure is not as high as during static exercise
Why does Diastolic blood pressure remain the same?
muscles are moving constantly, no added pressure on constant contraction
you are constantly breathing, which allows carbon dioxide to be quickly expelled
arteries are dilated as vasodilation is occurring
Describe the cardiovascular adaptation resulting from endurance exercise training
- Heart
- Stroke volume
- Resting HR
Heart Adaptation
- The myocardium (muscular tissue of the heart) increases in thickness
- The left ventricles internal dimensions increase
Stroke Volume
- The increase in size of the heart enables the left ventricle to stretch more and thus fill with more blood.
- The increase in muscle wall thickness also increases the contractility resulting in increased stroke volume at rest and during exercise, increasing blood supply to the body
Resting Heart Rate
- As the stroke volume increases the cardiac output can remain constant, therefore enabling the resting heart rate to be lower.
Describe the cardiovascular adaptation resulting from endurance exercise training
- Cardiac output
- Muscular adaptations
- Blood
Cardiac Output
- Cardiac output increases exponentially during maximal exercise, because of increases stroke volume.
- This results in a greater oxygen supply, waste removal and hence improved endurance performance.
Muscular Adaptations
- increased capillarization of the trained muscles.
- improvements in the vasculature efficiency
Blood
- resting blood pressure decreases as a result of improved cardiovascular factors.
- increase in blood plasma
- red blood cell volume and haemoglobin
Explain maximal oxygen consumption
Fitness can be measured by the volume of oxygen you can consume while exercising at your maximum capacity. VO2 max is the maximum amount of oxygen in milliliters, one can use in one minute per kilogram of body weight. Those who are ‘fitter’ have higher VO2 max values and can exercise more intensely than those who are not as well conditioned.
Factors affect VO2 max
The physical limitations that restrict the rate at which energy can be released aerobically are dependent upon:
the chemical ability of the muscular cellular tissue system to use oxygen in breaking down fuels
the combined ability of cardiovascular and pulmonary systems to transport the oxygen to the muscular tissue system
