Respiratory Notes from Lecture and Book

23.1 Overview of the respiratory system

Respiratory System: organ that provide oxygen to blood and gets rid of CO2

Function:

  • Gas change : get Oxygen, rid CO2

  • Communication; speech + vocalization

  • Olfaction: sense of smell

  • acid-based balance: Ph is controlled by eliminating CO2

  • Blood pressure regulation: The step angiotensin II( type of vasocontrictor) regulates blood pressure

  • Blood and lymph flow: the pressure in breathing helps blood and lymph go bacK to heart: makes a small vaccum

  • Blood filtration: The lungs help get rid of blood clots by filtering

  • Expulsion of abdominal content: hold your breath to help you poop, pee, and give birth

Principle organs: nose, pharynx, larynx, trachae, Bronchi, and lungs

Lungs—> bronchi—> bronchioles→ alveoli ( gas exchange )

Inspiration ( inhaling ): air goes to alveoli where gas is exchanged in the bloodstream and flows out during expiration

ZONES

Conducting: passages for air flow

  • nostrils—> bronchioles

Respiratory: alveoli and other thin-walled gas-exchanged regions

  • upper respiratory tract: nose→ larynx ( head—> neck)

  • Lower respiratory tract: trachea—> lungs ( respiratory organs

23.2 Upper respiratory tract

Nose:

  • warm/humidifies and cleanses hair as we breathe in

  • helps with odor detection and amplify the nose

  • nostrils/ nares—> has choanae or posterior nasal apertures

  • CONCHAE:

  • we have superior, middle and inferior conchae/turbinate

  • Conchae help mositure/ humidify and clean the air as it pass through meatus( narrow air passage ) —> also helps dirt and dust to get stuck on the mucous membrane

Sinuses:

  • not useful for the respiratory

  • adjacent from meatus ( i think)

  • help vocalize

  • hurtful if you have infection and are flying

  • Sinuses have blood supply but lack effective drainage when infected

Pharynx ( throat):

  • tubes connects nasal passageway to esophagus; swallowing and speech

  • Regions:

  • Nasopharynx: behind conchae and has pharyngeal tonsils; passes air

  • oropharynx: behind tongue; air, food and drink

  • laryngopharynx: Behind larynx: air, food, drinks

Larynx: Voice box—> keep food and drinks out airway—> sound production ( phonation)

  • Epiglottis: valve for directing food to esophagus

  • Rest= vertical—> swallowing: epiglottis is down preventing food and drink in coming in

  • Cartilages:

  • epiglottic: superior, elastic cartilage, spoon-shaped

  • Thyroid: adam’s apple—> box of the voice box→ largest→ C-shaped

  • Cricoid: inferior—> box of the voice box→ ring -like

  • Arytenoid: two of them—> behind thyroid cartilage—> make air flow movement easier and regulate it

  • Vocal cords: produce sounds not speech

  • intrinsic muscles work the vocal cords via arytenoid cartilages

  • Arytenoid —> abduct= free breathing—> adduct=speech

  • Force:

  • adducted= vibrations—> high pitched when tauted, low pitched when relaxed

  • males how longer and thicker vocal cords which explains why their voice is deeper

  • loudness is determined by force of the air

  • Speech production:

  • pharynx needs to be developed

  • sound is made by air flow working with lips, tongues

23.3 Lower respiratory

The Trachea: windpipe, C-shaped ringsn

  • Trachealis: smooth muscle—> relaxes when swallowing letting the esophagus to expand to pass food

  • Mucosa→ Pseudostratified columnar epithelium→ goblet cells + ciliated + short basal stem cells

  • Mucociliary escalator→ dust and particles trapped in the mucus + cilia drives them upward to pharynx= removal of debris

The Lungs and bronchial tree

Lung

  • base: bottom of the lung

  • apex: pointy top of the lung

  • hilium: is a slit in the lung- recieves main brinchus, blood vessels, lymphatic vessels and nerves

  • Bronchial Tree: branching system of air tubes

  • Conducting Zone—→ has a dead space bc it cant exchange gases either the blood

  • is the trachae→ branches of the lungs

  • parasympathetic stimulates muscularis mucsoae keeping it constricted = makes dead space smaller

  • while the sympathetic relaxes the smooth muscle to dilate the airway

  • Bronchioles: greatest control of airflow—> 1. mostly in conducting zone and 2. can change diameter

Alveoli- gas exchange region—> spongy sacs

  • alveolus: clusters of soap bubbles that have pores in their walls and exchange air to each other

    Cells

  • Squamous alveolar cells: 95% of alveolar surface that is thin for fast gas diffusion between air and blood

  • great alveolar cells: 5% round to cuboidal

  • Function fo great alveolar:

  • 1. repair squamous cells epithelium when damaged, 2. secrete pulmonary surfactant ( phospholipid + protein) coating alveoli and small bronchioles to prevent them from collapsing

  • alveolar macrophages → immune cells that idenitfy and get rid of waste and particles

  • Respiratory membrane—> think barrier between alveolar air and blood

  • Oxygen and Carbon Dioxide Exchange:
      - CO₂-rich blood enters the alveoli, where CO₂ diffuses out and oxygen enters (via a concentration gradient).
      - Factors influencing gas exchange efficiency include:
        - Gradient Strength: The larger the difference in gas concentrations, the faster the diffusion.
        - Surface Area: High surface area in healthy lungs allows more efficient gas exchange.
        - Conditions like emphysema reduce functional surface area by destroying alveoli, making it harder to exhale and increasing the work necessary for breathing.

Pleurae- serous membrane layer

  • visceral pleura- touching the lungs

  • parietal pleura- outer part

  • pulmonary ligament-. extends from pleura to connect with diaphragm

  • pleura cavity→ his pleural fluid and is a potential space

  • Function of Pleura:
      - Reduces friction during breathing via serous fluid and helps establish pressure gradients necessary for ventilation.

    It 23.3 Neuromuscular Aspects of respiration

Respiratory muscles

  • Diaphragm : prime mover—> contracts to flatten and lower ; ncreasing thoracic cavity volume, thus decreasing pressure within the lungs and allowing air to flow in.

  • Internal/ external intercostal muscles: primary function→ prevent from collapsing when diaphragm is lowered. Also help expand or contract the thoracic cavity—> see lab manual for each mechanism

  • Scalen: fixators that help elevate the ribsg

  • these structures recoil to make expiration

  • air isn’t thinner at higher elevation, the air pressure decreases making it harder to breathe

Respiratory Neuroanatomy

  • lungs have no pacemaker

  • Control levels are cerebral and conscious that allow us to inhale and exhale

  • Respiratory center ……

  • central chemoreceptors: brainstem neurons that response to the PH levels

  • Peripheral chemoreceptors: in the aortic arch ( communicate via Vagus nerves ) and carotid bodies ( communicate via glossopharyngeal ) that respond to O2/CO2 content and PH in blood

  • stretch receptors: in smooth muscle of bronchi+ bronchioles + visceral pleura. Respond to inflation of lungs

  • Irritant receptors; in brush cells and nerve endings. Respond to smoke, dust, pollen, chemical fumes, cold air and excess mucus. DRG respond with reflex like coughing, bronchoconstrictions, shallow breathing, or breath holding.

  • Higher brain centers: limbic system, hypothalamus and cerebral cortex influence the respiratory either by conscious control or emotion effect ( crying, gasping )

    Embryonic Development:
      - Lung buds develop from the floor of the pharynx, called the pulmonary groove.
      - Forming structures lead to bronchi and smaller bronchioles, culminating in the alveolar sacs for gas exchange.