Respiratory system Flashcards
Blood pH
pH is the measure of acidity, alkalinity and neutrality
Blood pH needs to be controlled within very narrow linits – 7.35-7.45
Low pH = elevated H+ ion concentration (more acidic)
High pH = more alkaline
Blood pH; Acidosis (respiratory and metabolic)
Respiratory acidosis results from raised CO2 in blood causes increased in H+ ions and therefore increased acidity
Metabolic acidosis from exercise = lactic acid & fasting = ketoacids which enter the blood
Ventilation helps lower the acidity of body fluids via exhalation of CO2.
Blood pH; regulation
Low pH (increase in acidity) is managed in 3 ways;
1) Buffer systems – temporarily bind to H+ removing them from solution (i.e. proteins, bicarbonate)
2) Increased exhalation of CO2
3) Kidney excretion of H+ (slow mechanism, kidneys can synthesis new & reabsorb bicarbonate, influencing pH
Cell respiration
The process of energy production (ATP) within cells.
Metabolic process whereby energy (ATP) is obtained by metabolising carbohydrates, fats and proteins
Glucose is primary molecule metabolised for ATP production. Fats & proteins also used. Energy is produced by either; Aerobic or Anaerobic respiration
Cell respiration; aerobic
Aerobic respiration - requires oxygen to generate ATP. Occurs in mitochondria.
Produces 38 ATP (total yield = net 36)
Requires carbohydrates (usually glucose but also fats and proteins)
Glucose + Oxygen = Water + Carbon Dioxide + ATP
Cell respiration; anaerobic
Anaerobic respiration in the absence of oxygen).
Occurs in the cytoplasm via glycolysis. Produces a total of 2 ATP molecules and lactic acid. Intensive short term activity.
Glucose = Lactic acid + ATP
Cells; Alveolar: cell types and functions
Type 1: Epithelial cells, covering 90% of alveolar surface, very thin (gas exchange)
Type 2: Secrete alveolar fluid that contains pulmonary surfactant – reduces surface tension, preventing alveolar collapse. The fluid allows gasses to diffuse through it.
Alveolar macrophages: Strategically located white blood cells (leukocytes) that engulf & destroy microbes entering the alveoli
Cells; Macrophages
Type of white blood cell that performs phagocytosis and engulfs and digests microbes and dead /worn out cells and stimulates the action of other immune cells
Coughing Reflex
First line of immune defense:
1. Epithelial receptors in the respiratory tract are highly sensitive to mechanical and chemical stimuli. The coughing reflex starts when irritation of the mucous membrane occurs
2. Stimulation sensitive nerve endings in the larynx, trachea, bronchi
3. A nerve impulse is sent via the vagus nerve to the respiratory centre in the brain stem
4. This causes deep inhalation and closure of the glottis (and vocal cords)
5. Contraction of abdominal / respiratory muscles to increase pressure
6. Forced removal if irritation
Deoxyhaemoglobin
Haemoglobin (Hb) that lacks oxygen
Functions of respiratory;
Voice / smell: Voice production & smell
Air; Warming, cooling, moistening of air
Gas exchange; O2 & CO2, O2 is required for cell respiration, CO2 is a waste product of cell respiration. By breathing, we are able to inhale O2 & exhale CO2
Immunity; Removal of inhaled particles (immunity); larger substances in nose & smaller substances in mucociliary escalator. Alveolar macrophages in alveoli
Gas exchange; Alveoli
In alveoli, oxygen and carbon dioxide are exchanged between air and blood. Gas exchange occurs between alveoli and capillaries. O2 moves from the alveoli (after beathing in), into the blood = oxygenated blood, CO2 moves from the blood (having been delivered via the pulmonary artery), into alveoli, to be exhaled. Movement of both gases occurs via diffusion
Alveoli have thin walls, large surface area for exchange and are next to a network of capillaries to help gas exchange
Gas exchange; Diffusion
Exchange of gases down the concentration gradient
Gases
(inhaled and exhaled)
Inspired air contains a large quantity of nitrogen and oxygen. Oxygen has a strong affinity with haemoglobin so will bind to Hb molecules. Nitrogen does not bind with haemoglobin and is not used or created in the body so does not dissolve in the blood.
Inspired:
Oxygen; 21%
Carbon Dioxide; 0.04%
Nitrogen; 78%
Expired:
Oxygen; 16%
Carbon Dioxide; 4%
Nitrogen; 78%
Gases in blood; Carbon Dioxide
Carbon Dioxide diffuses into the blood from respiring cells. Transported by:
70% plasma as HCO3 (bicarbonate (buffer)
23% in RBC (bound to Hb)
7% dissolved in plasma
Gases in blood; Carbon Dioxide – Bicarbonate buffer
Bicarbonate buffer reaction (to control blood pH):
Co2 diffuses down its concentration gradient from tissues into blood
* Because of the high water content of blood, CO2, combines with water to produce carbonic acid (H2CO3)
* As carbonic acid is unstable it decomposes immediately into bicarbonate (alkaline) and H+
* Hydrogen is exhaled and excreted into urine to reduce acidity. In addition, bicarbonate is alkaline, which buffers the acidity of blood to keep pH stable
Carbon dioxide + water = carbonic acid = bicarbonate + hydrogen (reversible reaction)
CO2 + H20 = H2CO3 = HCO3 + H+
Gases in blood; Oxygen
Oxygen is an essential gas in the body, cells use it to create the energy that is required for various processes.
98.5% of Oxygen in the blood is transported by haemoglobin,
1.5% of O2 is dissolved in plasma
Hypoxic
Lack of oxygen
Mucociliary escalator
Goblet cells secrete mucus. Mucus traps inhaled particles and acts as a surfactant. It’s also anti-microbial. Cilia move the particle laden mucus towards the oesophagus where it can be coughed up / swallowed (protecting the lungs)
Mucous membrane
The respiratory tract is lined with a mucus membrane. This is a ciliated epithelial membrane that contains mucus-secreting goblet cells.
Oxyhaemoglobin
When plenty of oxygen is bound to Haemoglobin (Hb)
Parts of the respiratory system; Adenoids
Nasopharyngeal tonsils
Parts of the respiratory system; Alveoli
Air sacs in lungs. Small hollow cavities that make up most of the lung volume. They act as sites of gas exchange in the lungs.
Parts of the respiratory system; Bronchi
The trachea divides into left and right bronchi at the vertebral level of T5. They deliver air into the lungs (The right bronchial is more vertical, shorter & wider = aspirated object more likely to enter right lung)
Parts of the respiratory system; Bronchioles
The bronchioles are continuous of the bronchi. They lead directly to the alveoli. Control of air-entry via;
Sympathetic nervous system (SNS; fight or flight) = broncho-dilation increases breathing rate (alongside vasoconstriction)
Parasympathetic nervous system (PSNS; rest & digest) = broncho-constriction slows breathing rate (alongside vasodilation)
Parts of the respiratory system; Epiglottis
Flap of cartilage that closes off the trachea during swallowing and prevents food entering (the windpipe) and entering the lungs
Parts of the respiratory system; Eustachian tubes
Connect the nasopharynx to the middle ear and allow equalisation of pressure in the middle ear
Parts of the respiratory system; Larynx
AKA the voicebox and connects the laryngopharynx with the trachea
Functions: Production of sound (vocal cords) and speech (tongue, lips, cheeks), protection (epiglottis), Air passageway, Warming and humidifying
Parts of the respiratory system; Lung Anatomy
Two cone-shaped lungs, separated by the heart, supplied by blood from the right and left pulmonary artery
Surfaces; Apex (extends above clavicle), Base (over diaphragm), Costal (rib) surface, medial surface
Lobes; Right lung = three lobes, Left lung = two lobes (due to heart)
Parts of the respiratory system; Nose / nasal cavity - structure and function
The nasal cavity is the first contact organ in the respiratory system & conditions air. Internally it has 3 nasal concha (turbinates) – shelves that increase surface area & trap water during exhalation. Contains olfactory receptors (smell). Conche = shell, Olfactory = smell, Septum = enclosure
Functions; Filtering air, warming air, humidification, sneezing reflex, olfactory function
Parts of the respiratory system; Paranasal sinuses
Air filled cavities within certain facial and cranial bones. Include frontal, ethmoid, sphenoid, maxillary.
Functions; Resonance in speech, Lightening of cranial mass, Nasolacrimal ducts drain tears from the eyes, Moisten / humidify air
Parts of the respiratory system; Pharynx
Straight muscular tube that connects the nose and throat. Consists of Nasopharynx, Oropharynx and Laryngopharynx
Functions; Passageway for air & food, Warming and humidifying, Taste, Hearing, Equalisation of pressure in middle ear, Immune protection, Speech
Parts of the respiratory system; Trachea
The trachea (AKA windpipe) is 12cm long, incomplete c-shaped rings of hyaline cartilage that is below the larynx and branches into bronchi. Carries air down to the lungs. Functions; Airflow, Mucociliary escalator, Cough reflex, Warming, humidifying, filtering.
Pleura and Pleural Cavity
Serous membranes that surround the lungs. The pleura contain a visceral and parietal layer, with a pleural cavity in between. The visceral and parietal pleura form a double layer separated by serous fluid and prevents friction.
Visceral = pertaining to organs, Parietal = walls of a cavity
Respiration - External
Between air / lungs and blood. Exchange of gases between the blood and lungs (air). Pulmonary capillaries carry blood around alveoli. Air is inhaled and exhaled – ventilation.
Respiration – internal
Between blood and cells. Exchange of gases between blood and cells
Respiratory Structures
Air flows through the following structures in the respiratory system:
Nose, Paranasal sinuses, Pharynx (throat), Larynx (voice box), Trachea (windpipe), Bronchi (left and right), Bronchioles, Alveoli (air sacs)
Surfactant
Lowers the surface tension of a liquid, allowing easier spreading. Mixture of lipids (hydrophobic) and proteins (hydrophilic) that forms a surface film in alveoli (pulmonary surfactant)
Surfactant = surface + active substance)
Tidal volume
Represents the normal volume of air that enters the lungs during inspiration when no extra effort is applied. Normal tidal volume = approx. 500ml
Ventilation
The process through which O2 and CO2 are transported to and from the lungs. 2 main phases; Inhalation (approx. 2 secs) and Exhalation (approx. 3 secs). Breathing can come from two areas; abdominal (diaphragmatic breathing) (where most breathing should come from) and upper rib breathing
Ventilation control
The control of ventilation is primarily involuntary. The respiratory centre is located in the brain stem and receives inputs from different body parts;
Chemical receptors in brain stem measure CO2 and acidity (H+ concentration). Chemical receptors in aorta & carotid artery measure CO2, O2 & acidity levels. Stretch receptors in walls of the bronchi & bronchioles detect over-inflation
Ventilation muscles
Two types of ventilation muscles; Primary and secondary
Primary; Intercostal muscles (internal and external), attached between ribs, contraction pulls ribs upwards (inhalation)
Diaphragm; contraction moves diaphragm into abdomen- draws air into lungs
Secondary; (AKA accessory muscles) assist in breathing. Located around neck and chest. Become shortened and fatigued.
Ventilation; Exhalation
A passive process – muscles relax. Occurs through elastic recoil of lungs (don’t need muscles to contract)
Ventilation; Inhalation
An active process requiring muscles. Negative pressure in thoracic cavity causes air to enter lungs down a pressure gradient
Vocal cords
Relaxed muscles = loose cords = low voice
Contract muscles = tight cords = high tone
