RESPITORY SYSTEM Flashcards
PURPOSE OF THE RESPITORY SYSTEM
BREATHING: breaths in O2 & out CO2 = respiration
GAS EXCHANGE: exchanges O2 for CO2 in body cells
PROTECTION: protects the body from harmful particles & germs
SENSATIONS: allows to smell
COMMUNICATION: allows us to speak and sing
PURPOSE OF THE RESPITORY SYSTEM
O2 = cell of the body needs energy for metabolic activities
Air moves into the body:
> warmed/cooled
> humidified
> cleaned
- Energy needs from the cells of the body, chemical reactions need O2 present to take place
- Waste product is CO2
- inhaled air moves through resptiroy tract into lungs = warmed and cooled depending on external enviroment
EMBRYOLOY DEVELOPMENT
3-5 weeks: lung (bud) develops, separates into 2 = right and left lung
- primative digestive tract
- outgrowth from the foregut (DEVELOPED INTO GUT) = called the respiratory diverticulum
- foregut forms tracheosophageal divides into two structures: oesophagus & trachea
5-16 weeks: lungs divide - 3 bud = right 2 bud on left.
- continue to divide (16 weeks, main and similar airways formed)
- cells start to appear = alveoli
- cartilage plates appear in the trachea and epithelial lining = goblet cells
- lung bud divides into 3 bronchi on the right & 2 bronchi on the left = lobes of the lung
16 weeks: all major elecments of lung formed except = invovled in gas exchange = respitoration = not possible
- 16-26 weeks: airways mature. Alveoli & blood vessels (pulmonary capillaries) = form smallest airways = lungs vascular organs
26 weeks of respiration possible = think wall sacs developed at the end respiratory bronchiles and lung tissue = vascularised. A fetus born at this time may survive with intensive care
26 weeks - birth: Alveoli develop, surfactant (lining made from a liquid mixture of lipids and protein secreted in epithelial cells)
- Production at this stage lines the alveoli, reduces surface
- the lung is filled with fluid until birth baby breaths for the first time
- The fetus gets O2 through the blood from the placenta in the uterus, getting CO2 through the blood
- hormoem & pressure generated by newborn loud cry = lung remove liquid was in the lungs
ANATOMICAL STRUCTURE OF RESPITORY SYSTEM
THE NOSE
EXTERNAL NOSE: made = cartilage & skin & lined with mucus membrane
BONY FRAMEWORK: formed by frontal, nasal & maxillary bones
Nostrials = opening into nostrils + main route of air entry into the respiratory system
- behind nostrils = large cavity walls formed by several bones of the face
- right & left cavities separated by nasal septum & sheet of bone & cartiliage
NASAL CAVITY
- Air enters
- Hair in the nasal trap, large particles/filter dust
- conchae from the passage (disrupts the flow of air)
- Air travels over moist mucosa saturated by water vapour (Humidified)
- warmed air by blood capillaries, mucus from goblet trap cells
- Cilia move mucus to the pharynx swallows/coughs up
- conchae = curved bone project into the nasal cavity = pathway for air flow
- function: increase the surface area of the nasal cavity = increased amount of air comes into contact with cavity walls = fast flow, making slow air, therefore spending longer in the nasal cavity - air warmed, filtered and humidified
PHARYNX
FUNCTION:
- passage for air & food
- hearing
- protection - for tonsils
- speech - chamber for sound
3 parts:
- nasopharynx - 2 opening (auditory tubes (ciliated epithelium, simple in shape and tissue cells with cilia on surface + contain goblet cells = secrete mucus moved towards the throat by cilia), Ciliated columnar epithelium
- Oropharynx - air & food passage (stratified squamous epithelium = stacked layers main function protect underlying strcutres from tearing and wearing ) lies behind the mouth & extends from the soft palate to the epiglottis
- Laryngopharynx air and good passage (stratified squamous epithelium) posterior (behind) the larynx respiratory & digestive tracts separate
The pharynx connects the nasal cavity to the larynx and oesophagus.
- The pharynx connects the nasal cavity to the larynx & oesophagus
- Tonsils are = part of the immune system
- lymphatic system produces antibodies due to swalling and inhaling
THE LARYNX
- connects pharynx & trachea
- 9 irregularly shaped cartilages attached by ligaments & membranes
> 1 thyroid cartilage (adam’s apple)
> 1 cricoid cartilage
> 2 arytenoid cartilages
> 1 epiglottis
FUNCTIONS:
- produces sound
- speech
- protection of the respiratory tract
- passageway of air
- humidifying, filtering + warming
- routes air and food towards the oesophagus stops from aspirating (accidentally swallowing something)
- houses vocal cords = vibrate to produce sound
LARYNX & VOCAL CORDS
THE TRACHEA
FUNCTION:
- support
- cough reflex
- warming, humidifying & filtering (air is typically at body temp when it reaches the trachea
- carries air away from the larynx towards the lungs lined with ciliated columnar epithelium, muscle = secreting goblet cells, inhaled debris & propelled towards the oesophagus & pharynx to be swollowed/washed up
THE TRACHEA
The tracheal wall is composed of 3 layers of tissue:
the lining which is the ciliated columnar epithelium
the middle layer consists of cartilages and bands of smooth muscle
and the outer layer which contains connective tissue that’s reinforced and is held open by cartiliage
BRONCHI AND LUNGS
2 primary bronchi
right lung: 3 lobes (superior, middle & inferior)
left lung: 2 lobes ( smaller due to the heart taking space) (superior & inferior)
- space between lungs called mediastinum
Function of bronchi/bronchioles
> control of air entry
> controlled by contraction/relaxtion of smooth muscles in walls = regulation of speed & volume of flow
PRIMARY BRONCHUS
right primary bronchus - right lung
left primary bronchus - left lung
- The bronchus divides into 2 branches = divided into smaller airways: bronchioles & terminal bronchials. The conducting zone finishes as they bring air into the lungs = walls are too thick to permit gas exchange
- Cartilage is for support in the large airways
- The surrounding lung is the pleural membrane, made from the visceral pleura
- Between the two pleura is known as the pleural cavity - containing pleural fluid lubricates lung movement when breathing
TRACHEA
- closed sac think serous membrane protects each lung
- visceral - adheres to lung
- parietal - inside of the chest wall
- important for normal breathing
- NEGATIVE INTRAPLEURAL PRESSURE = vacuum holding in 2 layers together = keeps lungs inlfated
- The pleural fluid allows the membranes to slide over each other and lubricates lung movement during breathing.
- The airways and the alveoli of the lungs are embedded in elastic tissue, which constantly pulls the lung tissues towards the hilum, but because the negative intrapleural pressure holds the two pleura together the lung remains expanded.
REPSIRATION ZONE
ALVIEOLI
- The walls of alveoli are made up of single layer of squamous epithelial cells = type 1 alveolar cells surrounded by flimsy basement membrane.
- Type 2 alveolar cells (septal cells) are cuboidal epithelial cells, scattered among type 1 cells. These secrete surfactant (detergent like substance) which coats the gas exposed alveolar surface, stops alveoli drying out and reduces surface tension preventing alveolar collapse during expiration.
- Secretions of surfactant start in about the 35th week of fetal life, its presence in newborns permits expansion of the lungs and the establishment of respiration immediately after birth. May not be present in sufficient amounts in immature lungs of premature babies causing serious breathing problems.
- External surfaces of alveoli covered with ‘cobweb’ of pulmonary capillaries. Blood flowing past on one side and gas on the other.
PULMONARY BLOOD SUPPLY
- The pulmonary trunk divides into the right and left pulmonary arteries carrying deoxygenated blood to the lungs.
- Within the lungs the pulmonary arteries divide into many branches which end in a dense capillary network around the alveoli.
- The exchange of gases between air in the alveoli and blood in the capillaries takes place and then the pulmonary capillaries merge into a network that forms the two pulmonary veins carrying oxygenated blood back to the heart.
BREATHING
- The process of air moving into (inspiration) and out (expiration) of the lungs.
- Average respiratory rate for an adult is 12-20 breaths per minute, this varies in children.
- The average respiratory rate for an adult is 12-15 breaths per minute. However, this varies in children who breathe at higher rates (due to smaller lung volumes and they metabolise nutrients at a higher rate than adults, so they need more O2 and get rid of more CO2).
Mention PEWS and NEWS here (NEWS allows for 12-20 bpm). So here we will look at how we breathe. Breathing can also be referred to as pulmonary ventilation and is the process of moving air into and out of our lungs, supplying oxygen to alveoli and getting rid of carbon dioxide.
- There are muscles involved in breathing these include: 11 pairs of intercostal muscles occupying the space between the 12 pairs ribs. We have our internal intercostal muscles involved in active expiration, like when we exercise, and external intercostal muscles involved in inspiration.
- We also have a diaphragm - a dome shaped muscle which separates the thoracic cavity from the abdominal cavity. It is attached by muscle fibres to the lower ribs and sternum.
During inspiration the external intercostal muscles and diaphragm contract, enlarging the thoracic cavity in all directions.
We do also have accessory muscles - which can be used if extra effort is required when breathing.
These muscles include the sternocleidomastoid muscles and the scalene muscles which link the cervical vertebrae to the first two ribs and increase ribcage expansion.
Forced expiration is assisted by the internal intercostal muscles and the abdominal muscles sometimes.
BREATING
3 PHASES:
> INSPIRATION
> EXPIRATION
> PAUSE
- Relying on the change of pressure
- Boyle’s law = pressure exerted by gas is inversely proportional to volume
- Breathing also depends though on changes in pressure and volume in the thoracic cavity.
- This is that as the volume of a container the gas is in increases, the pressure of the gas inside it decreases and as the volume of the container decreases the pressure of the gas increases.
CYCLE OF BREATHING
- Relating this to the respiratory system, our lungs are our containers, and when we breathe in, we increase the volume of these, causing the pressure of gas in our lungs to decrease.
- As the pressure inside the lungs is reduced and lower than atmospheric pressure, air will naturally flow into the lungs until there is no pressure difference.
- The process of inspiration is active as it needs energy for muscle contraction.
- Conversely, when we breathe out, the volume of our chest cavity reduces, so the pressure increases above atmospheric pressure; therefore, air moves out of our lungs and into the atmosphere.
- At the end of expiration, the lungs will always contain some air; this, along with the intact pleura, prevents the lungs from complete collapse.
Expiration is a passive process as it doesn’t require any energy. After expiration there is a pause before the next cycle begins. ]
As air will naturally flow from an area of high pressure to an area of low pressure.
GAS EXHCNAGE (EXTENRAL RESPIRATION)
- O2 diffusing from alveoli into the blood
- CO2 diffuses from blood to lungs
- will diffuse from an area where its partial pressure is higher to an area where its partial pressure is lower.
- External respiration/gaseous exchange is how oxygen diffuses from the lungs (specifically the alveoli) into the bloodstream and how carbon dioxide diffuses from the blood to the lungs.
- Gas exchange is a process that is happening continuously in our bodys. The diffusion of oxygen and carbon dioxide is dependent on pressure differences e.g between atmospheric air and the blood.
Atmospheric air. gases: nitrogen, oxygen, carbon dioxide, water vapour, and small amounts of inert gases. The table shows the percentages of each in inspired andis a mixture of .
-Each gas in this mixture exerts a part of the total pressure proportional to its concentration, i.e. the partial pressure (PO2 and PCO2). (Dalton’s Law is another useful gas law to be aware of that states the total pressure of a mixture of gases is equal to the sum of the partial pressures of the individual gases.)
This is relevant to the respiratory system as the differences in partial pressure dictate the movement of oxygen and carbon dioxide between the atmosphere, the lungs and the blood.
- A gas will move from an area where its partial pressure is higher to an area where its partial pressure is lower.
HOW ALVEOLI ADAPTED TO GAS EXCHNAGE
- thin respiratory membrane
- cell wall = one cell thick = short diffusion distance
- large surface areas of alveoli
- large surface area of capillaries
- As blood arriving into the lungs from the pulmonary artery has travelled from the body tissues it contains high levels of CO2 and low levels of O2.
- carbon dioxide moves down its concentration gradient from the blood into the alveoli until equilibrium with alveolar air is reached.
- oxygen diffuses from the alveoli into the blood ready to travel back to the heart via the pulmonary vein to be pumped around the body to the body tissues.
INTERNAL RESPIRATION
- exchange of base = diffusion between the blood in the capillaries in the cell body
- diffusion of gases across capillary membranes in the tissues.
Internal respiration is the exchange of gases by diffusion between blood in capillaries and the body cells.
Gas exchange does not occur across the walls of arteries carrying blood from the heart to the body tissues, as the walls are too thick.
- Blood arriving at capillaries contains the same PO2 as the blood leaving the lungs.
- As the blood has been saturated with O2 in the lungs it has a much a higher PO2 and lower PCO2 than the tissues.
-This creates a concentration gradient between the capillary blood and the tissues so O2 diffuses through the capillary wall into the body tissues from the blood and CO2 diffuses from the cells into the bloodstream.
TRANSPORT OF GASES - O2
- Carried in bloodstream by protein - haemoglobin - found in erythrocytes (red blood cells) = oxyhaemoglobin.
- Erythrocytes contain millions of haemoglobin proteins, each haemoglobin can carry 4 oxygen molecules.
- Oxygen and carbon dioxide are carried in the bloodstream.
Oxygen is carried by a protein called haemoglobin, which is found in the erythrocytes (red blood cells).
Erythrocytes contain millions of haemoglobin proteins, with each haemoglobin having the capacity to carry 4 oxygen molecules.
When oxygen combines with haemoglobin, it creates oxyhaemoglobin. - The amount of oxygen that is attached to haemoglobin at a given time is measured as an oxygen saturation (SaO2). Mention usual O2 saturations here.
