Human Respiratory & Circulatory Systems

Posted on Sep 21, 2024 in Biology

Metabolism

Metabolism is the sum of chemical reactions in cells. Adenosine triphosphate (ATP) is a molecule that provides energy for muscle movement. It’s present in small quantities and lasts about 1.2 seconds. ATP is consumed and recovered through:

  • Phosphocreatine: Creatine molecules that create energy. Used in anaerobic and alactic efforts (2-7 seconds).
  • Anaerobic Glycolysis: Short anaerobic efforts. Lactic acid is created. Oxidation of glucose produces ATP.
  • Aerobic Respiration: Long aerobic efforts. Glucose and fatty acid oxidation with oxygen. Energy spent is recovered.

Respiratory System

1. Functions

The respiratory system is responsible for the intake and transport of air to the lungs, gas exchange (oxygen in, carbon dioxide out), filtering, heating, and humidifying the air.

2. Structure and Components

  1. Nostrils and Mouth
  2. Pharynx
  3. Larynx
  4. Trachea
  5. Bronchi and Bronchioles (air distribution)
  6. Alveoli (gas exchange)

Lungs: Distribute air through the bronchi and facilitate gas exchange in the alveoli.

3. Respiratory Function

Respiration is the process of gas exchange. It involves these phases:

  1. Pulmonary Ventilation: Inspiration and expiration (driven by pressure gradients).
  2. Pulmonary Diffusion: Exchange of gases between the alveolar air and blood capillaries in the lungs (across the respiratory membrane).
  3. Gas Transport: Oxygen transport to tissues and carbon dioxide elimination. These gases are transported combined with hemoglobin and dissolved in plasma.
  4. Tissue Gas Exchange: Oxygen is delivered to tissues, and carbon dioxide is released.

4. Regulation of Respiration

Respiration is regulated both voluntarily (by the motor cortex) and involuntarily (by the brainstem).

5. Lung Volumes and Capacities

  • Pulmonary Ventilation: The volume of air that enters and leaves the lungs in one respiratory cycle.
  • Respiratory Frequency: The number of breaths per minute.
  • Residual Volume: The amount of air that remains in the airways after a forced exhalation.
  • Vital Capacity: The maximum amount of air that can be exhaled after a maximum inhalation.
  • Tidal Volume: The volume of air that enters and leaves the lungs during a normal respiratory cycle.
  • Inspiratory Reserve Volume: The additional volume of air that can be inhaled after a normal inhalation.
  • Expiratory Reserve Volume: The additional volume of air that can be exhaled after a normal exhalation.

Circulatory System

Systole: Contraction of the heart. Diastole: Relaxation of the heart. Cardiac Cycle: One complete sequence of systole and diastole.

1. Functions of the Heart

The heart is responsible for distribution, elimination, maintenance, protection, and transportation within the body.

Functional Parameters of the Circulatory System:

  • Heart Rate (HR): The number of times the heart beats per minute.
  • Cardiac Output (Q): The volume of blood ejected by the heart per minute.
  • Blood Pressure (BP): The pressure exerted by blood against the artery walls.
  • Blood Flow: The distribution of blood throughout the body, with greater flow to areas with higher metabolic needs.

2. Components of the Heart

  • Heart
  • Blood Vessels
  • Blood: Composed of plasma, platelets, red blood cells, and white blood cells.

Erythropoietin (EPO): A hormone that stimulates the formation of red blood cells.

Capillaries: Microscopic vessels that connect arteries with venules, facilitating the exchange of nutrients and waste products.