Circulatory System and its Functions

• Training affects the circulatory system.
• The circulatory system's main function is to pump blood throughout the body to keep us alive.

Circulatory System Functions

• Transport: Carries blood, water, oxygen, and nutrients, also removes waste.
• Body Temperature Control: Blood absorbs and carries body heat to the lungs and skin.
• Protection: Fights diseases with antibodies and uses blood clots to seal wounds.

Circulatory System Components

• The heart
• Blood vessels
• Blood
• Pulmonary and systemic circuits

The Heart

• Cardiac muscle contracts and relaxes, creating a heartbeat.
• Average resting heartbeat is 72 beats per minute, increasing with exercise.
• The heart pumps blood around the body.
• The body contains 5 liters (10 pints) of blood, which the heart pumps in less than a minute.
• The heart has four chambers: left and right atria (top) and left and right ventricles (bottom).
• Ventricle walls are thicker than atria walls.

Pumping Action of the Heart

• Deoxygenated blood (dark red) with carbon dioxide enters the right atrium.
• The right atrium pumps blood into the right ventricle through a valve.
• The right ventricle pumps blood through the pulmonary artery to the lungs for oxygenation.
• In the lungs, blood picks up oxygen and deposits carbon dioxide, turning bright red.
• Oxygenated blood returns to the left atrium through the pulmonary vein.
• The left atrium pumps blood into the left ventricle.
• Blood leaves the left ventricle through the aorta, distributing to the body.
• Blood loses oxygen in the body and returns to the right atrium to repeat the cycle.

Heart as a Dual-Action Pump

• The left side circulates oxygen-rich blood throughout the body (systemic circulation).
• The right side pumps oxygen-poor blood to the lungs for re-oxygenation (pulmonary circulation).

Blood Vessels

• Arteries
• Capillaries
• Veins

Arteries

• The aorta is the body's largest artery.
• Arteries carry blood at high pressure away from the heart.
• Arteries are the thickest blood vessels.
• Arterial structure includes:
  • Endothelium (inner lining).
  • Involuntary muscle and elastic fiber layer to control diameter.
  • Outer layer of tough fibrous tissue.
• Arteries divide into smaller arterioles, which then divide into capillaries.

Capillaries

• Capillaries are subdivisions of arterioles
• They are very small, only one cell thick in diameter
• They are semi-permeable to allow passage of carbon dioxide, oxygen, nutrients, and waste
• They are found in clusters to feed muscles, organs, and tissue
• Blood flows from capillaries into veins

Veins

• Veins are thinner than arteries but have a similar structure.
• Their involuntary muscle and non-elastic fiber layers are thinner
• The endothelium is the same as in arteries.
• Veins transport blood back to the heart.
• Veins contain valves to prevent backflow.
• Skeletal muscles help pump blood by squeezing veins
• Gravity assists blood flow in veins above the heart.
• Breathing causes pressure changes, creating a sucking effect on blood.
• The heart's pumping action also creates a sucking effect on nearby veins.

Blood Composition

• Blood consists of 45% cells and 55% plasma.
• Cells include red blood cells, white blood cells, and platelets.

Red Blood Cells

• Also known as erythrocytes
• They impart the red color to blood
• They are produced in the bone marrow.
• They contain hemoglobin to transport oxygen and carbon dioxide.
• The body produces and destroys up to 2 million red blood cells every second.

White Blood Cells

• Also known as leukocytes
• They are produced in bone marrow and lymph tissue (for the immune system).
• White blood cells fight infection by engulfing foreign bodies or bacteria.
• Pus in wounds is formed from dead leukocytes.
• A high amount of white blood cells can indicate leukemia (blood cancer).

Platelets

• Platelets aid in blood clotting.
• They are small fragments of larger cells.
• They clot and seal the skin and damaged blood vessels.

Plasma

• Plasma forms 55% of the blood's volume.
• It is mainly composed of water.
• It contains fibrinogen (for clotting), glucose and amino acids (nutrients), urea (waste), and some CO2 and O2.

The Pulse

• The pulse is caused by the heart pumping blood.
• Each heart contraction registers a pulse.
• Blood flow expands and contracts artery walls, creating a pressure wave.
• Pulse can be checked at the radial (wrist), carotid (neck), temporal (forehead), and femoral (groin) arteries.

Blood Pressure

• Blood flows through vessels at high pressure.
• Pressure is higher in arteries than veins.
• Blood pressure is measured with a sphygmomanometer.
• Two readings are taken: systolic (ventricle contraction) and diastolic (ventricle relaxation).

Blood Pressure Factors

• Age: Blood pressure is usually lower in young people.
• Sex/Gender: It may vary between males and females.
• Exercise: It increases blood pressure.
• Stress and Tension: Both can increase blood pressure.
• Circulatory System Condition: Failure in the heart and blood vessels.
• Angina: Heart lacks oxygen due to narrow vessels.
• Heart attack: Heart stops due to lack of oxygen.
• Stroke: Brain lacks oxygen.
• High blood pressure indicates the heart works harder to pump blood.
• Narrowed or blocked arteries can cause high blood pressure.
• Starving the heart muscle of oxygen may result in Angina, Heart Attack or Stroke.

Reducing Blood Pressure

• Regular exercise
• Healthy diet to control weight
• Stopping smoking
• Medications
• Stress management

Pulmonary Circuit

• Deoxygenated blood goes from the heart to the lungs and returns oxygenated.
• The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs.
• CO2 is exchanged for O2 in the lungs.
• Oxygenated blood is transported to the left atrium via the pulmonary vein.

Systemic Circuit

• Oxygenated blood is carried away from the heart to the body via the aorta.
• After circulating through the body, deoxygenated blood returns to the heart from the vena cava.

Exercise Effects on the Circulatory System

• Exercise increases the demand for oxygen
• Heart rate increases.
• Heat production increases and sweat removes waste products.
• Blood pressure increases temporarily.
• Skin blood vessels open to release heat, causing redness.

Respiratory System Components

• Air passages
• Lungs
• Diaphragm

Air Passages

• Nasal Cavity: Filters, warms, and moistens air with mucous membranes and cilia.
• Mouth: Allows air entry and is separated from the nasal cavity by the palate.
• Pharynx: Allows passage of food and air.
• Epiglottis: A flap that prevents food from entering the trachea.
• Larynx (Voice Box): Air passes through and produces the voice.
• Trachea (Windpipe): A flexible tube with cartilage rings to keep it open.
• Bronchus: The trachea branches into two bronchi.
• Bronchioles: Smaller tubes branching from the bronchi, leading to alveoli.
• Alveoli: Air sacs for oxygen and carbon dioxide exchange.

The Lungs

• They are protected by the ribs and diaphragm inside the chest cavity.
• The right lung has three lobes; the left lung has two.
• The pleura membrane surrounds the lungs, acting as a lubricant.

The Diaphragm

• This muscle sheet separates the chest cavity from the abdominal cavity.
• It contracts and relaxes to control breathing.

Ribs and Intercostal Muscles

• Ribs protect the lungs.
• Intercostal muscles aid breathing.

Action of Breathing

• Inspiration: Breathing in.
• Expiration: Breathing out.

Inspiration Process

• Chest cavity changes shape and size.
• The diaphragm flattens and moves downwards.
• Intercostal muscles raise ribs, enlarging the cavity.
• Pressure decreases, sucking air into the lungs.

Expiration Process

• The diaphragm and intercostal muscles relax.
• The chest cavity returns to normal size.
• Pressure increases, forcing air out.
• Resting breathing rate: 14-16 breaths per minute.
• Forced breathing rate during exercise: up to 50 breaths per minute.

Gaseous Exchange

• Oxygen is taken in, and carbon dioxide is removed.
• It occurs in the alveoli:
  • Carbon dioxide moves from blood to alveoli.
  • Oxygen moves from alveoli to red blood cells.
  • Red blood cells carry oxygen to the body.

Lung Volume Types

• Tidal Volume: Air volume per breath, increases with exercise.
• Vital Capacity: Maximum air exhaled after maximum inhalation decreases during exercise.
• Inspiratory Capacity: Air taken in after normal exhalation, increases during exercise.
• Respiratory Rate: Breaths per minute.
• Expiratory Reserve Volume: Air forced out after normal exhalation, slightly decreases during exercise.
• Residual Volume: Air remaining after maximum exhalation, slightly increases during exercise.

Composition of Inhaled and Exhaled Air

• Inhaled Air: High oxygen and nitrogen, low carbon dioxide.
• Exhaled Air: High oxygen and nitrogen, higher in carbon dioxide.
• Air Composition:
  • 79% Nitrogen
  • 21% Oxygen inhaled
  • 16% Oxygen exhaled
  • 0.004% Carbon Dioxide inhaled
  • 4% Carbon Dioxide exhaled

Short Term Effects of Exercise on the Respiratory System

• Increased breathing rate
• Deeper breaths to take in more air
• Oxygen debt occurs during anaerobic activity due to lactic acid buildup

Long Term Effects of Exercise on the Respiratory System

• Stronger chest cavity muscles
• Increased chest cavity size
• Increased vital capacity
• More oxygen entering the bloodstream per breath

Aerobic Respiration

• Requires oxygen:
  • Glucose + Oxygen = Carbon Dioxide + Water + Energy
  • Glucose & Oxygen: transported to cells by the blood stream
  • Carbon Dioxide: is transported by the blood to the lungs to be exhaled
  • Water: passes into the blood and is lost as sweat, moist breath and urine
  • Energy: is used for muscle contraction, metabolism and maintaining temperature.
• Used during long duration activities
• Energy is produced using oxygen

Anaerobic Respiration

• Occurs without oxygen:
  • Glucose = Energy + Lactic Acid
• Energy is released quickly from the incomplete breakdown of glucose.
• Muscles work so hard that oxygen cannot be delivered fast enough.
  • Glucose: comes from the bloodstream and glycogen in the muscle
  • Energy: is produced quickly and used for explosive activity
  • Lactic Acid: accumulates in the muscles making them feel tired.

Oxygen Debt

• Muscles respire anaerobically during vigorous exercise
• Glycogen stores are used as an alternative energy supply
• Anaerobic respiration lasts ~60 seconds
• Oxygen is borrowed, creating oxygen debt.
• Lactic acid accumulates in muscles.