pumlonary exam 2

pulmonary ventilation

moving of air in and out of the lungs by pressure changes between lungs and atmosphere

(inspiration and expiration)

inspiration

air flows into lungs.

happens when diaphram and intercostal muscles contract, → increasing thoracic volume and lowering lung pressure below atmospheric pressure

expiration

when air flows out of lungs

at rest, this is mostly passive- lung pressure goes up

diaphram relaxes, lungs recoil and lung pressure goes above atmospheric pressure

primary muscle in quiet inspiration 

diaphram 

contracts and flattens, increasing ventricle dimension of the thoracic cavity 

accessory muscle in quiet inspirtation

external intercostals
contract to elevate the ribs and expand the thoracic cavity in the anteroposterior and lateral dimensions

deep/forced inspiration muscles

• sternocleidomastoid

• scalenes (middle, posterior, anterior) 

• upper trapz

• pectoralis minor 

• Serattus anterior 

what does the pectoralis minor do in forced inspiration

elevates ribs 3-5

what do the upper trapz do in forced inspiration

they elevate the clavicle and upper rib cage

what does the serratus anterior do in forced inspiration

elevates ribs when scapula is fixed

what does scalenes do in forced inspiration

elevates first two ribs

what does sternocleidomastoid do in forced inspiration

elevates sternum

what is forced inspiration

The process of inhaling deeply and forcefully,

what is quiet inspiration

The process of inhaling gently and naturally, involving the primary diaphragm and intercostal muscles without force.

forced expiration

active process; quiet is passive

the process of exhaling air actively and forcefully, primarily using the abdominal and internal intercostal muscles.

forced expiration muscles

• internal intercostals

abdominal muscles

• rectus abdominis

• external oblique

• internal oblique

• transverse abdominis

what do the internal intercostals do in forced expiration

they depress the ribs 

what do the abdominal muscles do in forced expiration?

they contract to push abdominal contents upward against diaphram (reducing thoracic volume)

rectus abdominis

external oblique

internal oblique

transverse abdominis

what nerve controls ventilation in the diaphragm?

The phrenic nerve

phrenic nerve origin

cervical spinal cord, segments C3-C5

“345 keep the diaphram alive”

function of phrenic nerve in diaphram 

motor supply to the diaphram, sensory supply to central diaphram and associated pleura/peritoneum 

role of phrenic nerve in diaphram

essential for quiet and deep inspiration by contracting the diaphram

what nerve is responsible for contraction of intercostal muscles

intercostal nerves

intercostal nerves origin

ventral rami of thoracic spinal nerves T1-T11

function of intercostal nerves 

motor suppy to intercostal muscles, and sensory to skin and paritetal pleura

role of intercostal nerves

external: inpiration

internal: expiration

what nerves controls ventilation in the accessory muscles

• cervical spinal nerves ( spinal accesory nerve, cervical plexus nerve)brachial plexus branches

spinal accesory nerve

motor to sternocleidomastoid and trapezius muscles,

cervical plexus branches nerve in accessory muscles. 

motor to scalenes

brachial plexus branches

motor to pectoralis major

pec minor,

serratus anterior

during deep inspiration

expiratory muscles (abdominal wall) nerve for ventillation

lower intercostal nerves (T7-T11)

subcostal nerves (T12)

iliohypogastric/iliongual nerves (L1)

function of abdominal wall nerves

motor supply to rectus abdominis, obliques and transverse abdominis

role of abdominal wall nerves 

contact abdominal muscles during forced expiration to push diaphram upward 

what type of muscle is responsible for ventillation

smooth muscle

causes contraction and dilation of lungs

intrapulmomary (alveolar) pressure

pressure inside alveoli, drives airflow

atmospheric pressure

pressure of the air and environment around us

at sea level 760 mmHg

intrapleural pressure 

pressure of the fluid within the pleural cavity that surrounds the lungs

since lungs are elastic

they recoil inwards and collapse- chest wall, ribcage and associated muscles spring outward.

opposing forces create tension between lungs and chest wall which makes a vaccum

vaccum generates negative intrapleural pressure (maintains lung inflation by counteracting inward coil)

transpleural pressure

difference between alveolar pressure and intrapleural pressure

transpleural = alveolar-intrapleural

what is a positive transplueral pressure 

when alveolar pressure > intrapleural pressure (keeps lungs expanded)

what happens when intraplural pressure becomes higher than alveolar

transmural decreases and lungs may collapse

breathing cycle

governed by changes in thoracic volume and resulting shifts in alveolar pressure relative to atmospheric pressure, allowing air to flow in and out of the lungs.

rest phase

intrapulmonary pressure = atmospheric pressure (no airflow)

why is transmural pressure positive during rest phase 

to keep lungs from collapsing and to keep airways open and expanded

why is intrapleural pressure negative during rest phase

to make sure lungs to collapse (vaccum)

inspiration pressure levels

intrapulmonary pressure drops below atmospheric pressure, this causes a pressure gradient and air flows from areas of high → low pressure . environment → lungs

continues flow until both pressures are equal → airflow stops

expiration

air flows from high → low pressure

dipahram relaxes which causes lungs to recoil to original size

air flow continues until pressure is equal again in environment and alveoli 

boyles law

when volume increases, pressure decreases

airway resistance

inversely related with airway diameter; as resistance increases, airflow decreases.

as diameter increases, resistance decreases

parasympathetic

bronchoconstriction

sympathetic

bronchodilation

what is lung/thoracic wall compliance

ease of chest/lung expansion

high compliance= easy to inflate

what does lung/thoracic wall compliance tell us

how much lung volume changes when pressure inside lungs changes

C= Δv/Δp

if lungs are highly compliant, a small pressure change will produce a large volume change

if compliance is low, takes more pressure to expand things

pulmonary surfacent

surfacant- compiance increases and surface tension decreases

type II pneumocytes

alveoli are lined with a thin water based fluid. the water molecules attract to eachother and pulls alveolar walls inward

type II pneumocytes secrete pulmonary surfacant to disrupt hydrogen bonds

without type II pnemocytes, alveoli would collapse

forces for lung collapse 

elastic recoil of lungs

alveoli surface tension

forces against lung collapse

negative intrapleural pressure (vaccum)

pulmonary surfacant

tidal volume

air that is moved in and out during quiet breathing

(500mL)

inspiratory reserve volume (IRV)

extra air inhaled beyond tidal volume (3mL)

expiratory reserve volume (ERV) 

extra air exhaled beyond tidal volume

residual volume (RV)

air left in lungs after maximal exhalation (1200mL) or (1.2L)

prevents collapse and allows continuous gas exhange

capacities

combinations of 2 or more volumes for a borader measure of lung function)

Inspiratory capacities

IC= TV=IRV

(max air inhaled after normal exhalation)

functional residual capacity (FRC)

FRC=ERV+RV

(2.4L)

air left after normal exhalation; maintains gas exchange and prevents collapse 

vital capacity (VC)

VC= TV+IRV+ERV

(4.7L)max air exhaled after a full inhalation; indicator of respiratory muscle strength and lung expansion

total lung capacities (TLC)

TLC= VC+RV

(5.9L)

max air lungs can hold ; altered in restrictive and obstructive diseases

lung volume

specific amount of air lungs can hold during diff phases of breathing cycle

IRV

provides large backup capacity thats not used during normal quiet breathing but can be accessed during deep or forceful inhalation (excersise or respiratory effort)

ERV

additional air thats forcibly exhaled during quiet exhalation.

important during active breathing such as exercise, coughing or labored breathing

RV

prevents lung collapse/ ensures gas exchange between breaths