Respiratory and Cardiovascular Systems for the DAT
/Learn key DAT concepts related to structure of respiratory and cardiovascular systems, breathing mechanisms, gas exchange, blood composition, plus practice questions and answers
learn the key concepts of respiratory and cardiovascular systems for the dat
Table of Contents
Part 1: Introduction to respiratory and cardiovascular systems
Part 2: Structure and function of the respiratory system
a) Structure of the respiratory system
b) Gas exchange
c) Thermoregulation
d) Protection against disease
Part 3: Breathing mechanisms
a) Diaphragm, rib cage, and differential pressure
b) Resiliency and surface tension effects
c) Volumes and capacities
Part 4: Gas exchange and regulation
a) Diffusion and differential partial pressure
b) pH control and nervous system control
Part 5: Overview of the circulatory system
a) Components of the circulatory system
b) The heart
Part 6: Overview of blood
a) Blood composition
b) Blood flow
c) Gas exchange by blood
Part 7: Regulation from other systems
a) Nervous system control
b) Endocrine system control
Part 8: High-yield terms
Part 9: Questions and Answers
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Part 1: Introduction to respiratory and cardiovascular systems
Understanding the respiratory and circulatory systems is crucial for the DAT, and they frequently intersect. In this section, we'll begin by discussing the respiratory system, followed by an exploration of the circulatory system, delving into their structures and roles. To conclude, we'll offer DAT-style practice questions and answers.
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Part 2: Structure and function of the respiratory system
The respiratory system extends beyond its conventional association with breathing, and for comprehensive DAT understanding, a more detailed exploration is necessary. This section will begin by delving into the components and structure of the respiratory system, followed by an exploration of its fundamental functions. These functions encompass gas exchange, thermoregulation, and defense against diseases and particulate matter.
a) Structure of the Respiratory System
The journey of inhaled air begins through the nose and mouth, advancing through the pharynx, situated at the rear of the mouth, which also serves as a passage for food. Beyond the pharynx is the epiglottis, a cap-like structure that shields the larynx during swallowing, ensuring food travels to the esophagus, not the larynx. The air proceeds to the larynx, which houses the vocal cords, and then to the trachea, often referred to as the windpipe. From the trachea, the bronchi extend and facilitate air movement in and out of the lungs. These bronchi further branch into secondary bronchi, tertiary bronchi, and bronchioles. This intricate branching serves to increase the surface area for efficient gas exchange. At the culmination of this branching lies the alveoli, tiny sacs enveloped by blood capillaries that enable optimal gas exchange. The alveoli contain a surfactant layer, a soapy substance that prevents their collapse.
figure 1: Structure of the respiratory system
b) Gas Exchange
Gas exchange is the primary function of the respiratory system. Cells require oxygen for aerobic respiration, with the byproduct being carbon dioxide. Consequently, a continuous exchange of oxygen into the body and carbon dioxide out of the body is necessary. Once blood returns from the body to the heart, it is directed to the lungs to engage with the alveoli. Each minuscule alveolus boasts numerous capillaries, ensuring an extensive surface area for gas exchange. The microscopic nature of the alveoli and capillaries facilitates rapid diffusion of oxygen to the body, with just a single cell's distance to traverse.
c) Thermoregulation
The respiratory system actively contributes to maintaining homeostasis, a critical aspect of which is thermoregulation. Both air passing through the lungs and blood in the body play roles in heat dissipation through evaporative cooling. In some animals, like dogs, panting optimizes this process, allowing warm air from the lungs and warm blood in the tongue to interact with the cooler external environment. The respiratory system's nasal and tracheal capillary beds, in close proximity to the external body, can release heat and maintain temperature. These capillaries can expand or contract in response to temperature fluctuations. Vasodilation, where capillaries expand, increases blood flow through these capillaries, releasing heat. Vasoconstriction, the opposite, reduces blood flow, thus conserving heat.
d) Protection Against Disease
The respiratory system serves as a defense mechanism against diseases and foreign particles. Airflow follows two zones: the conduction zone and the respiratory zone. The conduction zone, spanning from the nose/mouth to the primary bronchi, is primarily responsible for conveying air to the alveoli rather than facilitating gas exchange. In this zone, particles are filtered through mucous membranes and cilia. Cilia, tiny nose hairs, waft mucus and trapped particles upwards and outwards via the ciliary escalator. Goblet cells secrete sticky mucus, while epithelial cells have cilia that sweep the mucus towards the pharynx. This system efficiently traps particles and pathogens, making them either swallowable or subject to expulsion.
In the respiratory zone, spanning from the bronchi to the alveoli, where mucus membranes or cilia would hinder gas exchange, a different disease protection mechanism is in place. Alveolar macrophages, found in the alveoli, engulf foreign particles, ensuring the defense against potential pathogens.
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