The Respiratory and Circulatory System Flashcards
Structure of the Respiratory System
Air enters the nose and mouth, convoluted lining and mucous membranes in the nose and nasal cavity warm and humidify the air. Hairs and muscous lining the nose traps debris. Air travels throug the pharynx before being diverted into the trachea by the epiglottis.
Pharynx
Region from the nasal cavity to the top of the trachea.
Epiglottis
Flap of elastic cartilage that covers the oesophagus during inhalation and covers the larynx during swallowing.
Larynx
Cartilage structure containing the vocal cords (mucous membranes that vibrate when air passes through).
Trachea
Made up of ‘C’ shaped cartilage rings that hold the structure open, ensuring that air can constantly pass. As its base, it splits into 2, each branch for each lung. The epithelial lining produces mucous trapping debris, where the cilia lining moves in wave like motions to take mucous and debris to pharynx to be swallowed.
Bronchi
At the end of the trachea, it splits into 2 primary bronchi, one for each lung. They split into secondary bronchi, which take air into each lobe of the lung. These than split into tertiary bronchi. The structure of bronchi is similar to trachea.
Bronchioles
The tertiary bronchi divide into bronchioles, which then split into terminal bronchioles. They don’t contain cartilage but rather smooth muscle, allowing them to control air flow to lungs, expanding when the body needs more oxygen. Cilia and mucous is also present.
Lungs
The lungs take up the entire chest cavity except for the space between them called the mediastinum. Each lung is divided into lobes, the left having 2 and the right having 3. The pleura (a membrane) covers the surface of the lungs (visceral pleura) and lines the inside of the chest (parietal pleura). Between these 2 layers is pleural fluid, which holds the lungs against the chest and allows them to slide. Inside the lungs, the smallest bronchioles open into clusters of tiny air sacs called alveoli. Each alveolus has a wall only one cell thick, and is surrounded by a network of blood capillaries, where gases move between the blood in the capillaries and air in the alveoli.
Nasal Cavity
Contains projections that increase the surface area. Filters, warms and moistens air. Contains smell receptors. Resonating chamber for speech, and hairs and mucous trap debris.
Intercostal Muscles
Muscles between ribs. They move the ribcage upward and outwards to increase the volume of the chest cavity.
Diaphragm
Muscle that separates the chest from the abdomen. it contracts and flattens downwards, increasing chest volume.
Ribs
Framework of the chest.
Ventilation
The process by which air is moved in and out of the lungs (air flows from a place of higher pressure to lower pressure, therefore, air flows into and out of lungs due to pressure difference).
Inspiration
The process of taking air into the lungs. To lessen the pressure inside the lungs, their volume must increase. To do this, the diaphragm and external costal muscles contract. The diaphragm becomes flatter and rib cage moves upwards and outwards, increasing the volume of the chest cavity. As the pleura adheres to the internal wall of the chest cavity, the lungs expand with the chest cavity. Due to the lower pressure created, air flows in via the trachea.
Expiration
The process of breathing out. The diaphragm and external costal muscles relax, so the diaphragm bulges into the chest cavity and the rib cage moves downward. This reduces the volume of the chest cavity, and lungs but increases air pressure in the lungs. Air flows out to have equilibrium.
Structure of the Lungs and Gas Exchange
- The alveoli’s give the lungs a large internal surface area so that large amounts of gases can be exchanged in a shorter period of time.
- Each alveolus has as much blood as possible close to the air in the alveolus, to maximise speed.
- The continuous flow of blood helps to maintain a concentration differential of oxygen and carbon dioxide between the blood and the air in the lungs.
- The wall of the alveolus is one micrometre thick so that gas molecules don’t have to move far when moving in and out of blood.
- The membrane of the alveolus is covered in a thin layer of moisture, as gases can diffuse into and out of the blood only when dissolved.
The Process of Gas Exchange
- Deoxygenated blood in the capillaries surrounding the alveoli is brought to the lungs by the pulmonary arteries.
- Oxygen dissolves in the moisture inside the alveolus and diffuses through into the blood, at the same time that carbon dioxide diffuses from the blood into the air (higher concentration then the air).
- This process happens due to a concentration gradient which is maintained by the constant flow of blood to the capillaries and the movement of air into and out of the alveoli as we breath in and out.
Emphysema
Disease caused by long term exposure to irritating particles. It can damage the alveoli, lessening the surface area of the lung. Because of the loss of elasticity, the lungs are constantly inflated, and breathing out becomes voluntary. Can’t be cured and only worsens.
Lung Cancer
Development of a mass of cells that divides uncontrollably in the lungs. tabacco and asbestos contains initiators and promotors of lung cancer. Most of the time, it begins in the bronchi, causing a mass production of mucous. Cells at the base divide more rapidly and the mucous becomes trapped, causing a rupture in the alveoli. Then a growth develops.
Lung Infections
Pneumonia is an infection. The inflammation causes secretion of fluid and mucus into alveoli, reducing air they contain and reducing surface area. Tuberculosis is an infection by the bacterium ‘mycobacterium tuberculosis.’ It is spread by droplets and hygiene prevents it.
Asthma
Difficulty breathing due to narrowing of the airways due to the bronchioles spasming. This occurs due to the smooth muscles contracting, inflammation causing the lining of the airways to thicken and mucus filling the airway. It can be an allergic and non-allergic response. Usually irritation causes mass mucus production, reducing the volume of air going in and out.
Circulatory System
The link between the cells inside the body and the environment outsides (to meet the cells requirements).
Blood
Is the transport link between the cells of the body systems. Some of its functions is to:
1. transport oxygen and nutrients to cells
2. Transports waste away
3. Transport hormones to cells
4. Maintain pH of body fluids
5. Distributing heat (maintaining body temp)
6. Maintaining water content and ion concentration in fluids
7. Protecting against disease
8. Clotting when vessels damage
Structure of Blood
Composed of 55% plasma, 41% erythrocytes, and 4% leucocytes and thrombocytes.
Plasma
Mixture of water and dissolved substances such as salts and sugars. It transports the components of blood, including cells, nutrients, wastes, hormones, proteins and antibodies throughout body.
Erythrocytes
Red blood cells. They have biconcave shape. They don’t have a nucleus, making them more flexible but limiting their lifespan to 120 days. Their function is to transport oxygen from the lungs to cells.
Leucocytes
White blood cells. Plays a role in protecting the body from infection. The different types are neutrophils, monocytes, lymphocytes, basophils and eosinophils.
Thrombocytes
Platelets. Small fragments of cells.
Neutrophils
Contains enzymes to digest pathogens.
Monocytes
Form other cells, like macrophages.
Lymphocytes
Involved in the immune response, cell mediated immunity uses T-lymphocytes and antibody mediated immunity used B-lymphocytes.
Basophils
Responsible for allergic reactions, producing heparin and histamine.