F206Pm - Respiratory System

Front 1

Upper Respiratory Tract: Demonstrate knowledge of it’s components:

Back 1

Nares, Nasal Vestibule, Nasal Conchae, Frontal Sinus, Ethmoid Bone, Sphenoidal Sinus,Nasal meatuses (superior, middle, inferior), Pharynx, Pharyngeal tonsil, Nasopharynx, Tongue, Hard palate, Soft palate, Uvula, Palatine tonsil, Lingual tonsil, Fauces, Oropharynx, Epilgottis, Vallecula, Laryngopharynx, Arytenoid, Hyoid Bone, Thyroid Bone, Vestibular Fold, Vocal Folds, Vocal Cords, Cricoid Cartilage, Trachea.

Front 2

Lower Respiratory Tract: Where gaseous exchange is facilitated.

Demonstrate knowledge of it’s components:

Back 2

Trachea– mucosa, submucosa, hyaline cartilage, adventitia. Lined with pseudostratified ciliated columnar epithelium. Carina, R/L Primary Bronchus, Hilum, R/L Secondary Bronchus, R/L Tertiary Bronchus, Bronchioles, Terminal Bronchioles, Alveolar Ducts, Alveoli. Parietal Pleura, Pleural cavity, Visceral Pleura, Diaphragm. R Lung – Apex, Superior Lobe, Horizontal Fissure, Middle Lobe, Oblique Fissure, Inferior Lobe, Base. L Lung – Apex, Superior Lobe, Oblique Fissure, Cardiac Notch, Inferior Lobe, Base.

Front 3

Describe Internal & External Respiration interms of Partial Pressure.

Back 3

Oxygen diffusion: Alveoli - Po₂ = 100mmHg. Oxygenated Blood - Po₂ = 100mmHg. Peripheral Tissue - Po₂≤40mmHg, oxygen diffuses into peripheral tissue. Deoxygenated Blood - Po₂ =40mmHg

Carbon Dioxide diffusion: Alveoli - Pco₂ = 40mHg. Oxygenated Blood - Pco₂ = 40mmHg. Peripheral Tissue - Pco₂≥46mmHg, Carbon Dioxide diffuses into circulatory blood. Deoxygenated Blood - Pco₂ = 46mmHg, Carbon Dioxide diffuses into Alveoli

Front 4

Hypoxaemia is defined as a reduction in blood O2. What are the 4 potential causes of hypoxemia?

Back 4

1. Hypoxic hypoxia: too little oxygen available to the lungs; this may be caused by low oxygen atmosphere, airway obstruction, drowning etc.

2. Stagnant hypoxia: inability of the heart to pump blood in sufficient quantities to meet the needs of the body

3. Anaemic hypoxia: reduced levels of functioning haemoglobin (this may be related to blood loss, conditions such as sickle cell disease where the shape of the haemoglobin is altered, or anaemia itself)

4. Histotoxic hypoxia: the inability of cells to take up the circulating oxygen.

Front 5

Why are COPD patient’s more susceptible to rightside heart failure?

Back 5

If a section of lung is poorly ventilated the pulmonary circulation constricts so that blood is not delivered to the hypoventilated region. In COPD there is likely to be widespread poor pulmonary ventilation and therefore widespread pulmonary constriction. Pulmonary vasoconstriction leads to pulmonary hypertension, which in turn increases the work load of the Heart in the Right Ventricle. This can result in cor pulmonale.

Front 6

What is hypercapnia?

Back 6

Hypercapnia refers to an increase in the PCO2 of arterial blood. PCO2 is proportional to carbon dioxide production and inversely related to alveolar ventilation (the greater the alveolar ventilation the lower the PCO2 and vice versa).

Front 7

Hypercapnia (elevated PCO2 levels) lead to a reduced pH (respiratory acidosis). The extent of acidosis is dependent on whether respiratory failure is acute or chronic. How do their presentations differ?

Back 7

Acute – Large increase in PCO2 with minimal increase in HCO3- as a buffer. Results in a significant drop in pH.

Chronic – the kidneys retain HCO3- which leads to increased serum bicarbonate levels and relatively normal pH levels. The body adapts such that chronic increases in CO2 so that patients with chronic hypercapnia may not show symptoms until PCO2 becomes significantly raised.

Front 8

What are the components of the Respiratory Centre and where are the located?

Back 8

Rhythmicity Area (Medulla Oblongata).

Pneumotaxic Area (Pons).

Apneustic Area (Pons)

Front 9

The Medullary Rhymicity Area controls the basic rhythm of respiration, describe the control it exerts.

Back 9

Inhalation is an active process. In quiet breathing. Inspiratory centre active for 2 seconds – impulses to External Intercostal Muscles (intercostals nerves) and Diaphragm (phrenic nerve). Contraction causes inhalation. When impulses stop, passive elastic recoil causes exhalation for 3 seconds. In forceful breathing, impulses from Expiratory Centre cause contraction of Internal Intercostal Muscles and Abdominal Muscles causing forceful exhalation.

Front 10

What does the Pneumotaxic Area do?

Back 10

Pneumotaxic Area – transmits inhibitory impulses to the inspiratory area, turning off inspiratory area before the lungs over inflate. When the pneumotaxic area is more active, breathing rate is more rapid.

Front 11

Desribe the function of the Apneustic Area.

Back 11

Apneustic Area – Stimulates the inspiratory centre, prolonging inhalation. The pneumotaxic area overrides signals from the apneustic area.

Front 12

Why would we want voluntary control of our pattern of breathing and what are it's limitations?

Back 12

Cerebral cortex has connections with the Respiratory Centre which means we can voluntarily control our pattern of breathing (protective control – eg. swimming). Ability not to breathe is limited by build up of PCO2 and H+.

Front 13

Discuss Chemical & Nervous Control of the Respiratory System

Back 13

Chemoreceptors are located in the Medulla Oblongata (respond to changes in CSF concentrations of PCO2 and H+), part of the Central Nervous System. Peripheral chemoreceptors are located in the Aortic Bodies (near aortic baroreceptors) and Carotid Bodies (near carotid sinus barorecptors), they monitor concentrations of PO2, PCO2 and H+ in the blood. They are part of the peripheral nervous system. Neurons from Aortic Bodies are part of the Vagus (X) Nerves. Neurons from the Carotid Bodies are part of the glossopharyngeal (IX) nerves.

Front 14

Are Chemoreceptors an example of Positive or Negative Feedback?

Back 14

Chemoreceptors participate in a negative feedback system to regulate levels of O2, CO2 and H+ in the blood. Increased levels of PCO2 and H+ (decreased pH) or decreased PO2, results in chemoreceptors stimulating the inspiratory area to become highly active. The rate and depth of breathing increases – hyperventilation. This allows inhalation of O2 and exhalation of CO2 until PCO2 and H+ are lowered to normal. Inspiratory centre has a stronger stimulation to PCO2 increasing than O2 decreasing (swimmers causing hypocapnia by hyperventilation, then holding their breath).

Front 15

What is another name for the Inflation Reflex and what does it do?

Back 15

The Herring-Breuer Reflex

Stretch receptors are located in the walls of bronchi and bronchioles. During over inflation, stimulus results in nerve impulses sent along the Vagus Nerve (CNX) to inhibit the inspiratory and apneustic areas. The result is exhalation,when the stretch receptors are no longer stimulated the inhibition ends and a new inhalation begins.

Front 16

Discuss 4 other factors that contribute to regulation of respiration:

Back 16

Limbic system stimulation – Anticipation of activity or emotional anxiety, sends excitatory stimulus to Inspiratory area increasing rate and depth of ventilation.

Temperature – Increase in body temp increases rate of respiration. Decrease in body temperature decreases respiratory rate. Sudden cold stimulus (plunge pool) causes temporary apnoea.

Pain – Sudden pain causes brief apnoea. Prolonged somatic pain causes increased respiratory rate. Visceral pain may decrease the rate of respiration.

Stretching the anal sphincter muscle – increases the rate of respiration. Sometimes used to stimulate breathing in a newborn baby or a person who has stopped breathing.

Irritation of airways – Physical / Chemical irritation of pharynx or larynx causes immediate cessation of breathing and coughing / sneezing.

Blood pressure – Sudden rise in BP decreases the rate of respiration. A drop in BP raises the respiration rate.