Lecture 7 Cardio respiratory regulation
Breathing is monitored by all the sensors.
Peripheral chemoreceptor: sense change in o2
Central chemoreceptor—sense co2 levels/pH levels in spinal fluid.
Stretch receptors in lunges—activate when expanded.
Irritant receptors—irritant-coughing reflex.
Positional receptors– in the joints and muscles that are activated during movement and exercise.
In mammals, the motor output of the system goes to diaphragm by phrenic nerve
Central brain controls breathing. Lot of important stuff here in pons and medulla.
Human arterial oxygen chemoreceptors (Carotid body)—Type I (glomus) cells are the O2 sensors.---Low o2, activate O2
sensor, closes K+ channels, depolarizes the membrane, opens Ca++ channels, intercellular Ca rises, and triggers a
For amphibians, there is a diffuse structure called the carotid labyrinth. It serves the same oxygen sensing role as the
mammalian carotid body. Only difference is that these cells are more diffusely organized.
Fish atrial/water o2/co2 chemoreceptors—O2 and Co2 receptors in gill arches. Internal oriented chemoreceptors-blood
sensing, externally oriented chemoreceptors, water sensing
Cardiorespiratory responses to hypoxia in fish: When partial pressure of O2 in water is decreased, hypoxia sets in and the
heart rate decreases Breathing frequency and breath amplitude increases.
Hypoxia= decrease inspired O2.
Central ph, Co2 receptors—in brain—Co2 diffuses through the capillary into the cerebral spinal fluid. The Co2 also combine
with water to make carbonic acid, which creates h+ and this is sensed by the receptors, since due to the blood-brain
dogma, the H+ does not pass through the walls.
Stretch response in lungs.—stop inspiring when the lung gets full. Lungs inflate-PSR (pulmonary stretch receptors_ fire-
input to brain NTS- terminates inspiration.
Some have chemoreceptors in lungs instead of the stretch receptors. Have CO2 receptors. Animals such and turtles or
snakes never stretch lungs, CO2 receptors work as stretch receptors.
Blood enters lung with high co2 and