4. When the heart contracts, blood then goes up the left ventricle and through the aortic valves. Left ventricle is our most muscular chamber of the heart because it is in charge of pushing blood around the body.

5. This aspect of the aortic raps behind the pulmonary artery. This is called the ascending aorta.

6. The curve here is called the aortic arch, goes right down and supplies the lower half of the body.

7. These 3 vessels supply the head and neck.

Blood coming back to the heart:

1. Comes back via two major veins. These are the superior vena cava and inferior vena cava. The superior vena cava brings blood back from the upper body. The inferior vena cava brings blood back from the lower body.

2. This blood pulls into the right atrium

3. Then passes through the Tricuspid valve and into the right ventricle.

4. When the right ventricle pumps, it pumps blood out the pulmonary valve into the main pulmonary artery. Which then subdivides into left and right pulmonary artery.

The Ventricular Septum: is a muscular lining that separates the left and right ventricles.

Atrial Septum: is a thin lining that separates the left and right atrium.

How does blood move through valves?

- Blood moves through valves because of pressure changes within the heart.

- Focusing on the left heart, the systemic circulation side. The pressure of the blood building in the left atrium forces the mitral valves open. (One example)

- Same process on the right heart, just that pressures are much lower.

- Blood can only move from areas of high pressure to areas of low pressure.

Cardiac cycle –

· Diastole – heart is relaxing.

- Left and right ventricle start to fill with blood.

- Once their done filling the blood left in the left and right ventricle is called end diastolic volume (EDV).

· Systole – heart is contacting.

- When your heart contracts not all the blood leaves the heart.

- This means there is a small amount of blood left in the left and right ventricle, this is called end systolic volume (ESV)

· Stroke volume – the amount of blood that is ejected from the heart each beat.

- SV = EDV – ESV

· Heart rate – number of times heart beats per minute (bpm)

· Cardiac output (Q) – amount of blood bumped per minute. Q = Heart Rate (HR) x Stroke volume (SV)

Acute Responses to Exercise –

· O2 demand increases

· Increases HR, SV and CO

· Chronotropic

- Increase in heart rate.

· Inotropic

- Increased contractility – beats harder.

· Increased O2 uptake from working muscles, more oxygen is getting pulled into the working muscles from the blood stream.

· Bohr shift – the oxygen within the blood, that is carried in the hemoglobin, gets pulled into the muscle quicker and a faster rate as the muscle needs more demand from oxygen. (Disassociates faster from the hemoglobin into the muscle)

· Heart works harder to meet the demand that the muscles are asking for in terms of oxygen supply.

· A-V O2 diff = Arterio-Venous O2 difference

- Difference in O2 content between the arteries and veins

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Key Principles:

§ A-V O2 diff – difference in O2 content between arteries and veins

§ VO2 max – maximum oxygen consumption

§ Flick equation: VO2 max = Q x (A-V O2 diff)

- VO2 max = HR x SV x (A-V O2 diff)

§ VO2 max = Delivery x Extraction

- VO2 max is an equation of what our heart can deliver through our cardiac output, to what our muscles can extract from the blood.

§ VO2 max is measured in the maximum amount of oxygen in millilitres, per kilogram of your body weight, per minute. (mL/kg/min)

Blood vessels –

· Three primary roles:

- Transportation: getting oxygen, hormones, nutrients where they need to be. Also get the waste product removed.

- Communication: substances travel in the blood which facilitate communication

- Homeostasis: temperature and blood pressure regulation

· Arteries

- Carry oxygenated blood away from the heart.

· Arterioles

- Arteries divide into smaller arteries and then arterioles. They branch from arteries and lead to capillaries. Important blood vessels that regulate blood pressure.

· Capillaries

- Blood vessels get even smaller and become capillaries. This is where diffusion takes place.

· Venules

- Allow blood to move from capillaries. Taking deoxygenated blood to the veins.

· Veins

- Deoxygenated blood back to the heart. Two major veins that come back to the heart: the superior vena cava and inferior vena cava.

Structure of blood vessels –

· Structure of blood vessels related to its function.

· All have three layers called intima, media and externa.

· Depending on the role the thickness of each layer differs

· Arteries get smaller coming down from heart.

· Capillary has one single cell layer, need to be naturally leaky, to allow oxygen and glucose to move through it easily.

· Veins have valves, arteries don’t.

Blood flow responses to exercise –

· On average at rest, cardiac output is 5 litres per minute.

· At high and intense exercise, cardiac output is around 25 litres per minute.

· At rest, 20-25% of blood is going to stomach. When exercising it can be as low as 3-5%

· At rest, 20% of blood is going to kidneys, when exercising this goes down to 2-4%

· At rest, 15-20% of blood goes to the muscles, during exercise it can be as high as 80-85%

· Our blood vessels can redistribute the direction of the blood to where it needs to be from areas its not as essential at that moment of time.

· Arterioles plays a key role in blood flow regulation and distribution.

- Regulates blood flow through a process called vasomotion.

- Vasomotion is the change in diameter of blood vessels.

- A vasoconstriction artery gets narrower.

- A vasodilation artery gets wider.

- For example when doing legs exercises, you will get vasoconstriction in your stomach and you will get vasodilation in your arterioles of your leg.

Venous return –

· Volume of blood returning to the heart via veins.

· Pressure within blood vessels drops the further away from heart.

· Highest pressure is in aorta.

· Further down pressure gets less and less.

· Veins have much less pressure than arteries, and they need to get blood back without that pressure gradient.

· A mechanism veins have is valves.

· Valves open to allow blood flow and close to prevent in moving backwards.

· Skeletal muscle activation pump - is a collection of skeletal muscles that aid the heart in the circulation of blood. It is especially important in increasing venous return to the heart.

- The skeletal muscles of the legs are particularly important skeletal muscle pumps as they prevent pooling of the blood in the feet and calves due to gravity.

The Lungs –

- Air comes in through our nose and mouth – nasal cavity.

- Air comes down our trachea (windpipe)

- Air travels down trachea and reaches small windpipes called bronchus.

- The bronchus subdivides into different direction into bronchioles.

- At the end of the bronchioles there are alveoli’s

- Alveoli’s is where the exchange of oxygen and carbon dioxide takes place.

Respiratory Physiology –

Upper respiratory tract –

The major passages and structures of the upper respiratory tract include the nose or nostrils, nasal cavity, mouth, throat (pharynx), and voice box (larynx).

Lower respiratory tract -

The lower respiratory tract consists of the trachea, the bronchi and bronchioles, and the alveoli, which make up the lungs. These structures pull in air from the upper respiratory system, absorb the oxygen, and release carbon dioxide in exchange.

- Air comes through nasal cavity.

- Come down the upper and lower respiratory tract and into the alveoli.

- Alveoli are little, tiny air sacks that are neatly rapped around tons and tons of capillaries.

- This is where CO2 comes from capillaries into the alveoli and breathed out.

- This is where O2 we have just inhaled moves into the alveoli and then into the blood capillaries and into the circulation.

Basic functions:

- This is what alveoli look like.

- 700 million alveoli in each lung

- Tightly integrated with blood vessels

- Gaseous exchange of oxygen and carbon dioxide between inhaled air and the blood stream

Functions of Alveoli:

· Thin lining – allows for fast diffusion.

· Larger surface area – This speeds up diffusion because gases have more area over which to diffuse

· Blood supply – the alveoli have a dense capillary network so that large volume of gases can exchange

Pressure changes:

- Changing of pressure in the thoracic cavity that forces blood to move in and out.

- As we breathe in our lungs fill, as they fill our thoracic pressure increases massively.

- When this pressure increases, the concentration of oxygen coming into the alveoli is much higher than what is in the blood stream. This means because the concentration is higher it is going to move one way. This is called inspiration.

- When we breathe out, our lungs recoil. This results in our thoracic pressure dropping.

- At this time point, we will have a high concentration of Co2 in the capillaries than in the alveoli. Therefore the Co2 will only move into the alveoli.

- Only moves from high areas of pressure to low areas of pressure

Key Features of Alveoli

Note