Process of Breathing

Respiratory Rate

the number of breaths taken in one minute, an important indicator of disease and pathology

Normal Child(Under 1) Respiratory Rate

30-60 BPM

By Ten Years Old Normal Respiratory Rate

18-30 BPM

Normal Adolescence/Adult Respiratory Rate

12-20 BPM

Respiratory Rate is Controlled By

Respiratory center in medulla oblongata

Complete Control of Ventilation is

A more complex interplay of many regions in the brain that signal pulmonary ventilator muscles to contract

Ventilation should be

Rhythmic, consistent, and provide body with sufficient O2 and remove CO2 in balance

Medullary Respiratory Center

set basic rhythm of breathing

Aortic and Carotid Body

Monitors blood PCO2, PO2, and pH, chemoreceptors

Pontine Respiratory Group(PRG)

Influences and modifies the medulla oblongata's functions, located in pons

Hypothalamus

Monitors emotional state and body temperature

Cortical Areas of the Brain

control voluntary breathing

Proprioceptors

monitor the position and movement of skeletal muscles and joints during exercise

Pulmonary Irritant Reflexes

Protect the respiratory zones of the system from foreign material

Inflation Reflex

prevents overinflation of lungs

Dorsal Respiratory Group(DRG)

maintains constant breathing RHYTHM, stimulates diaphragm and intercostal muscles to contract(inspiration), stimulates diaphragm and intercostal muscles to relax(expiration)

Ventral Respiratory Group(VRG)

involved in forced breathing through stimulation of accessory muscles involved, forced inspiration and expiration

Apneustic Center

portion of pons that is double cluster of neuronal cells, stimulate DRG, control depth of inspiration for deep breathing

Pneumotaxic Center

a network of neurons that inhibits the activity of neurons in the DRG, allowing relaxation after inspiration, and thus controlling the overall rate

Medulla Oblongata and Pons

work together to receive systemic stimuli in a dose-response(greater stimuli, greter feedback), negative feedback, respond mostly to CO2

Central Chemoreceptor

brain/brain stem, sense level of CO2 in blood

Peripheral Chemoreceptors

carotid arteries and aortic arch, sense levels of CO2 in blood

As CO2 increases

it diffuses across blood-brain barrier where it collects in ECF, leads to increased H+, decreasing pH, central chemoreceptors stimulate respiratory centers to initiate contraction of diaphragm and intercostal muscles (rate/depth of respiration increases to allow more CO2 to be expelled) to reduce blood levels of CO2/hydrogen ions

As CO2 decreases

low levels of hydrogen ions in brain lead to a decrease in rate/depth of respiration

Peripheral Chemoreceptor Sense Arterial Levels of H+

more acidic pH levels, stimulate increase in ventilation to remove CO2 from blood at a quicker which in turns help reduce hydrogen ions and increase pH to normal

Peripheral Chemoreceptors can sense LARGE

changes in blood oxygen levels

Peripheral Chemoreceptors can ONLY

sense dissolved oxygen molecules, not bound to hemoglobin

When levels of Oxygen Drop...

Hemoglobin releases oxygen

Blood Oxygen Levels Low(60 mmHg or less)

Receptors stimulate an increase in respiratory activity, requires large drop in oxygen because of hemoglobin presence

Increase body temperature

Increase in respiratory rate

Fight-or-Flight Response

Increase respiratory rate