The Cardiorespiratory System

Topic 5: The Cardiorespiratory System

Index

• The cardiorespiratory system is composed of the respiratory system, the circulatory system, and the lymphatic system.
• This topic introduces the generalities of the respiratory and circulatory systems, the respiratory tract, pulmonary ventilation, gas exchange, regulation of respiration, the circulatory system, blood, blood vessels, the heart, blood circulation, cardiac regulation, adaptation of the circulatory system to exercise and the lymphatic system.

The Respiratory System: General Information

• Cells use oxidation of organic matter to obtain energy through cellular respiration in the mitochondria.
• This respiration process requires organic matter and oxygen.
• Animals developed respiratory systems with epithelium for oxygen diffusion.
• In humans, the lungs are responsible for gas exchange.

Actions of the Respiratory System

• Gas exchange is achieved in thin epithelia in the alveoli and the pulmonary capillaries.
• Gases get delivered from outside to the epithelium through respiratory openings.
• The mobility of air achieved through pulmonary ventilation needs to be renewed to introduce fresh oxygen
• Inspirations is the entry of air into the system, and expiration is the exit.
• Air must enter at an adequate temperature and humidity, a process which occurs in the nasal cavity.
• Solid particles that enter our body are adhered in the nasal cavity.

Respiratory Tract: Histology

• The respiratory system is composed of an upper and a lower airway.

Upper Airway

• The upper airway is comprised of openings that include nasal and oral cavities, nasal cavity and pharynx
• Digestive and respiratory systems share parts of the upper airway
• It is composed of pluriestratified epithelium with mucous glands and prismatic pseudo-stratified ciliated cells.

Lower Airway

• The lower airway includes the larynx, trachea, and the bronchial tree.
• In the trachea and bronchi, the epithelium is pseudo-stratified columnar ciliated, formed by goblet cells that make the mucociliary apparatus.
• Connective tissue supports the epithelium and includes blood vessels and nerves.
• The smooth monolayer epithelium is composed of pneumocytes.

Alveoli

• Alveoli contain pneumocytes for gas exchange and macrophages for defense and cleaning.

Respiratory Tract: Anatomy and Physiology

Upper Airways

• Include the nasal passages, the pharynx and the larynx.

Nasal Passages

• These are two large cavities in the buccal cavity
• The nostrils open to the nasal passages, and the pharynx through the choanae.
• The floor of the nasal passages is constituted by the palate and the superior by the nasal bones.
• The nasal passages are separated by the nasal septum.
• On the lateral walls are three shell-like structures called turbinates.
• The nasal passages have hairs to trap any foreign objects
• The epithelium lining is ciliated with mucus-secreting glands to trap any dust.
• The mucosa of the turbinates has a red pituitary effect which humidifies and traps particles.

Pharynx

• Carries air and food
• Contains glands
• It is divided into 3 parts:
  • Nasopharynx: The upper part, where the pharyngeal tonsils and Eustachian tubes are situated.
  • Oropharynx: Extends between the soft palate that holds the uvula.
  • Laryngopharynx: The final part communicates with the esophagus that includes the epiglottis.

Larynx

• Includes the larynx, trachea, bronchi tree, alveoli and lungs.
• Larynx: it is made of cartilages revested with cartilage.
• Internally, it presents a tight opening called glottis delimited laterally by vocal chords, superior ventricular bands and inferior vocal chords.
• Vocal chords open during intense inspiration.
• Tension combined with air output produces sonic vibrations.

Trachea

• A constantly open cylinder that communicates the larynx with the bronchi and the lungs.
• It is 10-11 cm long and 2 to 2.5 cm in diameter in adults
• It presents twenty cartilage rings
• These rings maintain the trachea constantly open during inhalations and expirations
• The trachea is extensible to allow movements.
• The trachea divides when approaching the lungs.

Bronchi and Bronchioles

• The bronchi is a continuation part of the conducting part of air from the trachea to the alveoli.
• The trachea initially ramifies into two primary bronchi directed to the lungs.
• There are three primary lobar bronchi on the right right lung and two on the left.
• Then come the bronchioles, and the secondary and tertiary bronchi.

Alveoli

• The alveoli are the terminal sacs that come from the capillaries, where the gaseous exchange takes place between inspired air and the blood.
• Around 500m alveoli with and area of 140m^2 between both lungs.
• The alveoli are saccular and internally recuperates by a liquid called the surfactant.
• This tensioactive substance reduces surface tension and aids with the spread of gases and prevents the collapse of the alveoli
• Alveoli are associated with blood vessels in intimate contact.

Lungs

• Lungs are are formed by the set of bronchi, bronchioles, alveoli, veins, arteries, blood vessels and connective tissue which unit them.
• They are protected inside the rib cage by the ribs, sternum and intercostal muscles.
• The right lung presents three lobes and the left contains two connected to a concavity.

Hilio

• A zone where the bronchi, arteries and veins penetrate the lungs.
• The bronchi divides in bronchioles in order to lead the gases towards the alveoli.
• The lungs are coated by a 15cc double layer called the pleura which contains fluid produced by the pleural liquid

Pulmonary Ventilation

• This action renews air content in pulmonary zones
• This action involves two respiratory movements.

Inspiration

• The active process occurs through the contraction of intercostal and diaphragmatic muscles that contract increasing the volume of the thoracic box
• Lungs increase because of membrane movements.
• Pressure decreases in the alveoli, and air travels inside

Expiration

• Is a passive process.
• Muscles relax
• Lung size reverts
• Air comes out.

Gas exchange

• Gas exchange occur via diffusion from an area of more concentration, towards an area of low concentration.
• The determining factor is the partial pressure of each gas.
• Partial pressure is directly proportional to its concentration.
• In a mix of gases each gas flows to a region from higher pressure to lower pressure.
• This air that enters the alveoli has partial superior pressure to the oxygen in the small arteries of the capillaries and thus the oxygen flows inside the blood.
• With CO2, the opposite occurs.
• The capillaries facilitate gaseous exchange
• Ones the gases are exchanged the oxygenated blood transports oxygen through pulmonary veins towards the heart, where then it it then pushed towards the tissues in the body

Oxygen transport

• Oxygen has a low solubility, though its bond with hemoglobin allows its transport.
• Hemoglobin is a transporter module consisting of 4 sub-unites and an iron atom.
• Each Hemoglobin unit can unite to 4 oxygen cells

CO2 Transportation

• Majority of the transported carbon dioxide is in the form of bicarbonate ions. Some is transported directly in the plasma, and the left over, remains bound to hemoglobin.

The regulation of respiration

• The nerve impulses control the rate and amplitude of respiratory movements
• The most important nerve center situated in the MEDULLA OBLONGATA, is the RESPIRATORY RATE ZONE
• It gets informed through interoceptors sends orders to the muscles to start the inspiration and expirations.
• Too much Carbon Concentration goes directly to the respiratory system, or through sensitive recipients in the aorta and carotid arteries
• Respiratory zones also have connections to the brain to alter the respiratory.

Circulatory System: Generalities

• Main function is to transport nutrients, gases and residue through the body.
• The circulatory system consists of blood and lymphatic systems:
• Blood System: Contains blood, hearts, and blood vessels .
• Lymphatic System: Contains the lymph.

Blood

• Blood is a type of conjunctive tissue
• Made of cells suspended in liquid that transport substances to the body, and has a viscous red hue
• It is composed of two parts:
• Blood plasma. (55%)
• Formed elements (45%): Which are white blood cells, red blood cells and cell fragments.

The main functions are:

1. Transportation of nutrients to cells.
2. Collection of waste residue for excretion purposes, for example carbon in lungs or salts and urea in kidneys.
3. Defence from infections due to its white blood cells.
4. Transportation of hormones for coagulation purposes.

Composition

Blood Plasma

• Liquid with yellow hue
• Contains water (91% approximately)
• Proteins
• Mineral salts , lipids etc.

Form Elements (45%)

• Are cells and cellular fragments , such as platelets , which result from the red bone marrow.

Blood Groups.

• The blood groupings are a classification used for the blood , according to the characters present from the red globules or serum , as well as being used for transfusions and illnesses.

The classifications for blood groups are:

• System ABO.
• Rhesus (Rh) factor.

Blood Vessels

• Blood vessels form a large web designed to transport blood to the heart and tissues, and from tissues back to the cells.

Blood Vessel type: Arteries

• Are blood vessels that transport blood from the heart outwards
• Their structure includes:
• Tunica adventitia = external layer from conjunctive tissue that transports deoxygenated blood.
• Tunic media= The middle tunic is made of elastic tissue that keeps blood pressure regulated
• Tunica International = The internal tunic is covered by endotelial tissue

Blood Vessel Types: The Veins

• Transports blood from the arteries to the heart.
• Tunica Adventist: More thick.
• Tuna media: Thinner
• Tuna Internal
• Valves prevent reverse flow from the blood towards the heart vessels.

Blood Vessel Type: Capillaries

• Are vessels that are more thinner, that shape only from layers of endothelium .
• Thin width allows CO2 AND 02 circulation to happen from the surrounding organs by which the capillaries are irrigated through .They shape web that is dense . Its walls facilitate the output from oxygen and nutritive substances from its tissues and the entrance by co2 and substance from the cellular metabolisms.

The structure includes:

• Arterioles: Vessels coming out of the arteries.
• Venules: Vessels that move towards the heart.

The veins

• Superior and Vana Cava
• Jugular and subclavian
• Illiac

The Heart

• Is the main organ that propels blood through the vessels
• Lies in the center of the thoracic zone near the mediastinum and inside the thoracic cavity.
• Its external part presents two sulcus: transversal and longitudinal
• The cardiac histology has three layers: pericardium, myocardium and endocardium

Pericardium:

• This is a double layer to isolate the heart muscles from foreign organisms.
• Epicardium: a visceral layer that is attached to the myocardium.
• Parietal Layer: a layer attached to all the adjacent organs .

Myocardium

• The most voluminous layer
• Formed by cardiac muscle tissue
• Allows transmission and contraction for both layers as needed.

Endocardium

• Formed by a endothelium that continues inside of the vessels.
• Four chambers: known as cardiac camera
• The superior layers are the auricles and they receive the blood flow from vessels.
• The inferior layers are known as the ventricules that work for pumping the blood vessels.
• In between the auricles and the ventricles there is a membrane that isolates (interventricular). -The right auricle receives blood from vena cava -The right ventricle sends blood to arteries.

The cardiac cycles:

The heart also produces rhythmic movements

• Systole movement occurs upon contraction of muscle tissue
• Diastolic movements occurs during states of relaxation

During systole movements is when the heart is in diastolic phases, and the opposite occurs.

Heart rate is 72 beats per min. which has a duration of 0.8 seconds. the heart emits sounds, and the valve closes allowing for ventricular systole to occur.

The first diastole = relaxation enters the heart from cavs. Second systole= auricular is when the blood from a enters v. Thirst systole = Ventricular when the blood flows through arteries.

Blood circulation

• In human beings the blood is circulated in the form of terrestrials through two parts:
• First Smaller pulmonary part: which collects the oxygen in the lungs, at the same time releasing co2 inside of them. Second, Largest corporal and systematic: where oxygen is released to the tissues.

Cardiac regulators

• The nerves contract and can regulate the heart. It also comes regulated by an autonomic signal for nervous connections

Adaption to the Circulatory System During Workout

• Cardiac regulators control heart contraction
• Nervous signals can coordinate blood flow
  • These adaption may require a greater need of blood, smaller need of heart beat to adapt the arterial density to those who workout.
  • Heartbeat can also decrease during workout
  • More blood vessels, more strong ones for those whom work out.

The lymphatic system.

• Blood pressure is so high that fluid will pass though the capillaries
• The lymphatic system will recollect it.
• Lymphatic vessels are very large that will prevent flow and retain the direction.
• Fluids connect which other inside of a conjunction between vessels that generates a strong defense immune system for organism, since it returns the liquid from the damaged capillaries.

The functions of them are:

• Backwards route from the blood.
• Defensse antigens from the immune tissue
• Carry from intestine to liver, use system for transportation of nutrients.

The thymus

• The organ lies behind the sternum. it is composed of 2 zones and as a embryological component grows more than a child as it matures. Functions
  • Maturation of T lymphocites
  • Secretion of Hormones.

Red bone marrow

The tissue that recollects red bodies, vertebrae, sternum and skull zones the tissue generates hematopoietic components and maturation of lymphocites .