Neuromuscular Reflexes Overview

Neuromuscular Reflexes

• Reflexes are rapid, involuntary motor responses to stimuli.
• The overall process involves: stimulus → sensory neuron (transmits sensory info) → CNS processing → motor neuron → muscle contraction.
• Spinal reflexes (e.g., patellar reflex) involve tapping a tendon, stretching a muscle, triggering a sensory neuron to transmit signal to the CNS (spinal cord). The CNS processes the signal and sends a command via a motor neuron to contract the muscle.
• Brain stem reflexes (e.g., pupillary light reflex): Light stimulates sensory neurons in the retina, sending signals to the brain stem (specifically). This results in the iris muscles contracting to constrict the pupil, thereby regulating light entering the eye. There is a cross-connection between the eyes, so light in one eye causes a reflex response in the other eye.
• These reflexes evaluate central nervous system function, spinal cord function, peripheral nervous system function, and sensory/motor neurons.

Cardiovascular Parameters - Blood Pressure and Heart Rate

• Vital signs reflect essential physiological functions.
• Blood pressure is the driving force for blood flow, measured as systolic/diastolic pressure. Systolic pressure is generated by left ventricle contraction; diastolic pressure occurs when the left ventricle relaxes.
• Blood pressure is measured using a sphygmomanometer and a stethoscope, placing the cuff around the brachial artery
• Heart rate is measured through feeling the pulse (radial pulse), multiplied by 4 to account for the 15-second interval.
• Heart rate increases during exercise to deliver more oxygen to tissues.
• Vital signs are used to evaluate the circulatory system functionality (heart, blood vessels, breathing)

Cardiac Auscultation

• Heart sounds are produced by valve closures.
• S1 (lub) is the sound of atrioventricular (AV) valve closure (during systole)
• S2 (dub) is the sound of semilunar valve closure (during diastole).
• These sounds can be interpreted by a healthcare provider during cardiac auscultation for diagnostic purposes.

EKG Monitoring

• EKG (electrocardiogram): Monitors the electrical activity of the heart.
• Depolarization initiates activity starting in the sinoatrial (SA) node (in the right atrium). The signal travels through the atria, to the atrioventricular (AV) node (located between the atria and ventricles), then to the bundle of His, and finally spreads throughout the ventricles to stimulate them to contract.
• An EKG can be used to evaluate heart rate and rhythm (using intervals between QRS complexes and the timing of P-QRS-T waves).

Spirometry/Lung Volumes

• Spirometry assesses breathing and lung volume capacity.
• Tidal volume (TV): the volume of air inhaled and exhaled during normal breathing
• Inspiratory reserve volume (IRV): the additional volume that can be inhaled beyond the tidal volume.
• Expiratory reserve volume (ERV): the additional volume that can be exhaled beyond the tidal volume.
• Residual volume (RV): the volume of air left in the lungs after maximal exhalation; vital for lung health, necessary for continuous gas exchange.
• Spirometry can facilitate identifying potential lung diseases.

Blood Typing and Hematocrit

• Blood typing determines the presence of specific antigens (A, B, Rh).
• Blood type compatibility is crucial for blood transfusions; recipients need to be compatible with the donor blood type to avoid transfusion reactions.
• Hematocrit measures the percentage of red blood cells in whole blood.
• Lower hematocrit levels indicate anemia.

Urinalysis

• Urinalysis evaluates urine for physical, chemical, and microscopic characteristics.
• Physical characteristics include color (e.g., red indicates blood), clarity, and specific gravity (measuring urine concentration).
• Chemical characteristics may indicate substances like glucose, protein, or abnormal levels.
• Microscopic examination allows for observation of cells or other components, providing insights into kidney health or infections.

Pulse Oximetry

• Pulse oximetry measures oxygen saturation of hemoglobin in the blood.
• This measurement is presented as a percentage ranging from 95% to 100% saturation indicating adequate oxygen delivery.

Other

• Exercise increases both heart and respiratory rate.
• Normal blood pressure values are given, but are not detailed in this document.