The Respiratory System

Breath in sanskrit is pranayama.

Pranayama : Vital Life Force

The respiratory tract (pharynx, larynx, Trachea) conducts air to the lungs where gases (O2 and CO2) are exchanged between the air and the blood stream.

The respiratory tract is lined with mucosa, which warms, filters and humidifies the air. The air enters the nasal passage and into the pharynx. The air passes by the epiglottis, a flap that keeps food from going into the larynx.

In ujjayi pranayama, the epiglottis is constricted slightly to give a sibilant sound to the breath. The air passes down the trachea and into the lungs via the primary, secondary and tertiary bronchi.

The smallest air distribution tubes are the alveolar ducts, which take the air to the alveoli, small inflated sacs where gas exchange occurs. the oxygen in the air is exchanged for the carbondioxide in the blood.

Mechanics of Respiration

During inhalation, the diaphragm contracts, flattens out and lowers down and the external intercostals contract, raising the ribs up and out, which creates decreased pressure in the thoracic cavity and air flows into the lungs.

During relaxed exhalation, the muscles relax and the air is pushed out of the lungs by the elasticity recoil of the lungs, ribcage and muscles.

During forced exhalation, the internal intercostals and abdominal muscles contract to actively push the air out of the lungs.

(Pilates Breath & Breath of Fire)

During forced inhalation and upper chest breathing, accessory muscles (scalenes, pectoralis minor, sternocleidomastoid) assist in elevating the ribcage and sternum.

Belly Breathing - Abdominal Breath

Nadi Shodhana -

Applied Practice

Breathing Affects Posture & Movement

On inhalation (In) the head moves back and the cervical curve flattens, the shoulders move back and the thoracic curve flattens, and the lumbar curve increases and the pelvic rotates anteriorly.

Exhalation (Ex) reverses the effects. Inhalation is linked to raising the arms, lifting the chest, extending the back (back bends), and straightening the spine. Ex is linked to lowering the arms, compressing the abdomen (forward bends, lateral bends, and twists), and moving out of back bends.

In will either lift you more fully into a posture or create more tension in the body. Ex will either relax you further into a posture or reduce tension. (Unless you are practicing pilates breath or breath of fire)

Our main focus in asana practice is linking our awareness to the movement of our spine through or breath.

Mulabunda (Pelvic Floor)

Uriyana Banda: Pull in & up / Stretches the diaphram

Main mussel of respiration: Diaphram

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The Nervous System

Nervous System

Functions in communication and control with fast, short-lived electrochemical signals.

Organization:

-Central Nervous System (CNS)

-Brain

-Spinal Cord

-Peripheral Nervous System (PNS)

-Cranial Nerves (12 pair)

-Spinal Nerves (31 pair)

-Autonomic Nervous System (also considered part of the PNS)

-Sympathetic Division

-Parasympathetic Division

-Cerebrum

The cerebral cortex, only 4 mm thick, makes up the largest mass of the brain. It is divided into 4 main functions areas:

1.The frontal lobe is the center for conscious thought and voluntary movements.

2.The parietal lobe is the center for the somatosensory input.

3.The occipital lobe is our primary visual cortex.

4. The temporal lobe is our primary auditory cortex.

Sub-cortical Areas

The basal nuclei function in maintenance of muscle tone and posture and that tracts relay nerve impulses.

The corpus collosum integrates the left and right hemispheres of the brain.

The reticular formation is a group of neurons that has projections to many part of the brain.

Brain Stem

Thalamus integrates sensory impulses resulting in motor responses, regulates and maintains conscious state.

Hypothalamus regulates emotional behavior and autonomic reflex behavior, secretes hormones that affect the pituitary gland, and mediates descending impulses related to reflexive and skilled movement.

Epithalamus (pineal gland) produces melatonin related to diurnal cycles.

The midbrain is composed of descending nerve tracts and other nerves that relay impulses.

The pons relays cortical impulses to the cerebellum.

The medulla contains vital control centers.

Cerebellum

The cerebellum integrates equilibrium, posistion sense, fine movement, muscle tone, and muscle coordination.

Spinal Cord

Ascending Tracts are the pathway of ascending impulses, especially muscle stretch/position sense.

Descending Tracts are the basic pathway of descending impulses, especially motor neurons to create movement and hold posture.

Meninges and Cerebrospinal Fluid

There are 3 meninges that surround the spinal cord: Dura Mater (Outer Sheath), arachnoid mater (middle sheath) and pia mater (inner sheath).

Subarachnoid space contains cerebrospinal fluid.

CSF also circulates through the ventricles in the brain. Function of CSF is to cushion and protect the brain and the spinal cord.

Peripheral Nervous System (PNS)

Cranial Nerves

There are 12 pair if cranial nerves that can be sensory – receive afferent impulses from sensory receptors, motor – send efferent impulses to muscles, or a combination.

Insert Video on Cranial Nerve Names youtube

Spinal Nerves

There are 31 pairs of spinal nerves that exit the spinal cord and pass through the segmental intervertebral foramen between the vertebrae.

The posterior nerve root receives sensory neuron information, which is related to interneurons and ascending neurons in the spinal cord, which carry the signal to the brain.

The anterior nerve root sends the motor information to the muscle it innervates. A motor unit is the motor neuron and the muscle fibers it innervates. The alpha motor neuron connects to between 3 muscle fibers ( eye muscles) and 300 muscle fibers (gluteus maximus)

The degree of control over the motor unit is evident… the alpha motor neuron is part of a web of 600 local neurons in the spinal cord, with each having their influence (either excitatory or inhibitory).

These 600 upper motor neurons are connected to 10 billion other neurons within the brain, each of them having their controlling influence. The final outcome is dependent on the mutual consensus of all these competing signals.

Spinal Reflexes

A synapse is a junction between two neurons.

Monosynaptic reflex – a single synapse btw a peripherial sensory and motor neuron. Ex. Knee Jerk

Polysynaptic reflex – multiple synapses btw sensory, motor and interneurons. Ex: crossed-extensor reflex

Nerve Plexus – a plexus is a network of interconnected nerves

Cervical Plexus: C1-C4

Brachial Plexus: C5-T1. Musculocutaneous, axillary, median, radial, ulnar nerves.

Lumbar Plexus: L1-L5. Femoral, obturator n’s.

Sacral Plexus: S1-S3. Sciatic, Common peroneal, tibial n’s.;

Sciatic Nerve: from lumbar and sacral plexus L4-S3; The Nerve enters the lower limb by exiting the pelvic through the greater sciatic for men, below the Piriformis muscle. It descends midway in the greater trochanter of the femur and the tuberosity of the ischuium, and along the back of the thigh to about its lower third, where it dives into two large branches, the tibial and common peroneal nerves.

(Video)

Sensory Receptors

Exteroceptors: Skin-touch, pressure, temp., free nerve endings

Autonomic Nervous System

Sympathetic Division stimulation results in “fight or flight” responses:

Sugar and fat enter the bloodstream as fuel for muscles and the brain.

Respiration rate increases to raise o2 in the blood.

Heart rate and BP increases to speed delivery of o2 and fuel to cells.

Muscle tone increases.

Increased hormonal output via hypothalamus … epinephrine.

Blood flow id diverted from the gut to the muscles.

Attention and Alertness Increases.

Parasympathetic Division Stimulation results in “relation” responses:

Decrease in HR and BP

Skeletal Muscle Tone Decreases.

Lowered Level of arousal with EEG shifting toward alpha brain waves.

Pranayama and Brain Function

Research has shown that changes in breathing correspond to nervous system changes.

Puraka (Inlahation) stimulates the Sympathetic division of the ANS changes associated with breathing and stress.

With each inhale, our heart rate increase slightly and with each exhale, our heart rate decreases slightly.

Ultradian Rhythms are biorhythms in body.

Every few hours, the dominant activity in the brain shifts from one side to the other.

The left brain is associated with logical reasoning and linear thought.

The right brain is associated with theoretical, conceptual and artistic creativity.

This shift is associated with theoretical, conceptual and artistic creativity.

This shift is associated with a corresponding shift in nasal laterality.

Breathing through the left nostril (Ida Nadi) stimulates the right hemisphere and breathing through the right nostril (Pingala nadi) stimulates the left hemisphere.

By adjusting our breathing, we can have control over these changing rhythms.

Meditation (dhyana) and Brain Function

Brain EEF shows that in our normal waking state, the brain emits mostly beta waves. In meditation, the brain emits predominantly alpha and theta waves.

There is a shift in blood flow in the brain, as well, with increased blood flow to the prefrontal cortex (attention, imagery) and decreased blood flow to the left superior parietal lobe (external stimulus, logic, association and orientation).

Other physiological effects of meditation include reduced Sympathetic nervous system arousal, increased activation of the hippocampus, which affects heart rate and endocrine function, synchronization of neuronal firing in the brain and increased levels of serotonin, melatonin, dopamine and beta endorphins in the brain.

The Endocrine System & Reproduction System

Endocrine System

The endocrine system is comprised of ductless glands that secrete hormones into the blood stream. The hormones circulate and come in contact with target organs where they have their effect.

Homeostasis is the body’s maintenance of normal temperature, blood pressure, serum chemical levels, etc. Negative feedback are used to maintain homeostasis in the body. When the hormone levels are high, they inhibit the hypothalamus and anterior pituitary, resulting in a decline in their levels.

Positive feedback occurs in some unique cases, like child birth.

The hypothalamus, part of the brain, has a direct connection (neurological and vascular) to the pituitary gland.

The thyroid gland covers the anterior surface of the 2nd- 4th tracheal rings and secretes thyroxin, which increases oxygen consumption oat the cellular level thus increasing body metabolism. The thyroid gland also secretes calcitonin, a hormone that brings excess calcium from the blood serum into the bones.

The parathyroid glands, small “buttons” of cells on the back of the thyroid gland, secrete parathormone, which maintains normal blood calcium levels by promoting bone breakdown (osteoclastic activity)

The adrenal glands, which secrete several important hormones, lie on top of the kidneys.

They secret mineralocorticoids that encourage the reabsorption of water by the kidneys, glucocorticoids that stimulate the formation of glucose in the liver, epinephrine and norepinephrine which elicit the sympathetic “fight or flight” response.

The pancreatic islets are endocrine tissue composed of alpha cells that secrete glucagons, which causes glycolysis (the breakdown of glycogen to glucose) and gluconeogenesis (the formation of glucose from amino acids); and beta cells that secrete insulin, which facilitates the movement of glucose out of the blood into cells and the formation of glycogen from glucose in the liver.

Decreased insulin secretion or decreased numbers or activity of insulin receptors leads to glucose intolerance and/or diabetes mellitus.

Thymus – Production of the white blood cells

Male Reproductive System

A yogic practice of urinating and then stopping the flow was recommended for a healthy prostate gland.

Female Reproductive System

The menstrual cycle is a 28-day cycle initiated and maintained by hormones. Ancient Yogic texts explain that there is a strong downward flow of apana energy and that this natural flow is upset by full inversions (sirsasana, sarvangasana, halasana, all arm balances)

The main focus of the practice of yogasana during pregnancy is to do what is most protective of the baby. Practice should be gentle as not to cause distress. The first three months are critical as the embryo implants in the uterus. Inversions are generally contraindicated after the first trimester, however, this depends on the woman’s condition and experience. There is a risk that the baby will entangle in the umbilical cord or present as a breech at delivery.

Yogasana practice that focuses on breathing and preparation of the muscles of the pelvic floor is indicated. Deep stretches are not advised as relaxing causes ligaments to soften in preparation of the birth canal for delivery.

During menopause, declining levels of estrogen upset the balance between hone-building cells (osteoblasts) and bone-breakdown cells (osteoclasts). The resulting weak bones are subject to fracture. Yoga provides good mechanical stress on bones to decrease the effects of osteoporosis.

Yoga & Aging