Respiratory System Revision Notes PDF

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RESPIRATORY SYSTEM REVISION NOTES: INTRO AND ANATOMY OF THE LUNGS, AIRWAYS AND BLOOD SUPPLY 

Describe the main anatomical ft. of the airways an gross anatomical ft. of the lung: The upper respiratory tract consists of the Nasal cavity, the pharynx and the larynx, sinuses, tonsils. The lower respiratory tract consists of the trachea, the primary bronchi and the lungs. The epiglottis is a leaf shaped cartilage that stops food from going down your windpipe as it moves down and covers the trachea when eating The lungs are pyramid shape organs that are vital in the tole of gas exchange. They are connected to the trachea by the left an right bronchi. The right bronchi is slightly more vertical than the left therefore inhaled objects are usually found stuck there. At the base of the lungs there is the diaphragm which is dome shaped. It descends on contraction which increases thoracic volume which allows respiration to take place.

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Identify the different classes of airways and pneumocytes: Pneumocytes are a type of cell that lines the alveoli in the lungs Type 1 Pneumocytes: Simple squamous epithelium (large thin cells) which cover 97% of the alveolar surface an are vital for gas exchange. They are susceptible to toxic insults and cannot replicate itself. Type 2 Pneumocytes: Responsible for secretion of surfactant. Phospholipids and protein which decrease surface tension at the alveolar surface which decreases the work of breathing. Smaller than type 1 pneumocytes but can replicate to replace any damaged type 1 pneumocytes. The breakdown of the lungs goes: Trachea, primary bronchi, smaller bronchi, bronchioles, alveoli

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Functions of the Respiratory System: Gas Exchange – produces energy Acid base balance – maintain and regulate body pH Infection protection – cillia, mucous Communication via speech

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What is the difference between pulmonary and systemic circulation: Pulmonary circulation – delivers CO2 to the lungs an picks up O2 Carries blood to an from the lungs from the right side of heart through lungs to left side of heart. Arteries carry low O2 and high CO2 Veins carry High O2 and low CO2

Systemic Circulation - Carries blood to and from body tissues except lungs Carries blood from left side of heart through the body to the right side of the heart Arteries carry High O2 and Low CO2 Veins carry Low O2 and High CO2 

Identify points of gas exchange between the respiratory an CV systems: Exchange 1: Between the atmosphere and lung Exchange 2: Between lung and. Blood ( pulmonary artery circulation) Exchange 3: Between blood and cells

ANATOMY OF CHEST WALL AN MECHANICS OF BREATHING 

Be able to describe the anatomy of the pleural cavity: Right lung – Consists of 3 lobes ~ Superior, middle and inferior Left lung – Consists of 2 Lobes ~ Superior and inferior Each lung is enclosed in 2 pleural membranes (parietal and visceral) Intrapleural fluid is between thoracic wall and lungs. The pleural cavity is the space between the parietal and visceral pleura

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Understand the relationship between pleural and visceral pleura: Visceral pleural membrane – Coats outer surface of the lungs Parietal pleural membrane – coats inner surface of ribs The parietal pleura is sensitive to pain, temperature and pressure however the visceral pleura is not.

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Describe how the muscles of respiration act to inc and dec thoracic volume: Boyles law: pressure exerted by gas is inverse to volume Therefore an increase in volume leads to a decrease in pressure. The muscles of inspiration are – diaphragm (oes most of the work), external intercostals, sternocleinomastoids and scalenes The muscles of expiration are – internal intercostals and abdominais. Expiration is passive at rest however these muscles are utilised in severe respiratory load. As the diaphragm contracts it moves down which increases thoracic volume which leads to a drop in pressure which pulls air into the lungs

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Relate Boyles law to the mechanics of breathing: Boyles law states: In a closed space, pressure exerted by a gas is inversely proportional to its volume; Therefore an increase in volume leads to a decrease in pressure and a decrease in volume leads to an increase in pressure

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Mechanical factors that affect respiratory minute volume: Respiratory minute volume is the volume of gas inhaled or exhales from someone lungs per minute (tidal volume x respiratory rate) Flow of air between alveoli and atmosphere is proportional to the difference between atmospheric and alveolar pressures and inversely proportional to the airway resistance. Elastic recoil affects resp minute vol. as does radii of airways

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Explain why intrapleural pressure is always less than alveolar pressure: Pip is always negative (in healthy lungs) PA may be positive or negative dependant on atmospheric pressure

VENTILATION AND COMPLIANCE 

Define various lung volumes and capacities an their normal values: Anatomical dead space: vol of gas occupied by conducting airways that is NOT available for gas exchange (150mL) Tidal vol: Vol breathed in an out at each breath (500mL) Expiratory Reserve vol: Max vol of air which can be expired from lungs at end of norm expiration (1100mL) Inspiratory reserve vol: Max vol of air which can be inhaled into lungs at end of normal inspiration (3000mL) Residual Vol: Vol of gas in lungs at end of maximal expiration (1200mL) Vital Capacity: Tidal vol + IRV + ERV (4600mL)

Total lung capacity: Vital capacity + RV (5800mL) Inspiratory capacity: TV + IRV (3500mL) Functional Residual Capacity: ERV + RV (2300mL) 

Describe the difference between pulmonary and alveolar ventilation: Pulmonary ventilation is the total air movement in an out of lungs Alveolar ventilation is the fresh air getting to alveoli and therefore available for gas exchange Both are measured in L/min

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Normal values for alveolar and arterial gas partial pressures: Arterial gas: PaCO2 = 35-45mmHg PaO2 = 80-100mmHg Alveolar gas: PaCO2 =

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What is the role of pulmonary surfactant and the law of laplace: Pulmonary surfactant is produced by type 2 alveolar cells its production starts at 25weeks an is complete by 36weeks. It is stimulated by thyroid hormones an cortisol. Surfactant decreases surface tension therefore lowering the risk of alveoli collapsing Surfactant also decreases the lungs tendency to recoil and makes breathing easier Surface tension occurs where there is an air-water interface, and refers to the attraction between water molecules Surfactant is most affective in small alveoli as the surfactant molecules come closer together therefore increasing the concentration The law of LaPlace states that pressure is higher in smaller alveoli (P=2T/r) Where T is surface tension, r is radius an P is pressure

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Define compliance and factors affecting it: Compliance is the change in volume relative to the change in pressure. It is affected by disease stated (emphysema etc.) an is also affected by age. Compliance represents the stretchability of lungs High compliance = large inc in lung volume for a small decrease in ip pressure

Low compliance = small inc in lung volume for a large decrease in ip pressure 

What is the difference between obstructive and restrictive lung disease: Obstructive = obstruction of airflow, especially on expiration Restrictive= restriction of lung expansion Obstructive; Asthma, COPD, emphysema, Chronic Bronchitis Restrictive; CF, Infant Resp Distress, Oedema, Pneumothorax

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Tests used to determine lung function: Spirometry: this can be static an only consider the volume exhaled or it can be measured dynamically which considers the time taken to exhale a certain volume.

EMBRYOLOGY 

Define the stages of embryology: Pre-embryonic – 0-3 weeks Zygote formed and divides to form blastocyst. It them moves through uterine tube to the uterine cavity Embryonic phase – 4-8 weeks Foetal Phase – 9-40 weeks

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Describe fertilisation and gamete formation: One sperm pronucleus fuses with ovum pronucleus which gives a diploid zygote cell. This cell divides via mitosis, a MORULA is formed (ball of cells). As the size increases, getting nutrition to the core becomes harder therefore a cavity develops (blastocystic cavity). The outer lining of cells in called the TROPHOBLAST ; This all occurs in week 1.

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Describe blastocyst formation an implantation: Implantation occurs in the uterine endometrial layer – placenta begins to develop. The trophoblast divides to form 2 layers call the CHORION. The chorion helps implantation via the chorionic villi. This forms part of the placenta an secrets HCG which is used to detect the pregnancy...