Human Anatomy & Physiology I

Structure of the Parasympathetic Nervous System (PNS) The parasympathetic nervous system (PNS) originates from the craniosacral region: it arises from the brainstem (cranial nerves) and sacral spinal cord (S2-S4). Cranial nerves involved include the vagus nerve (cranial nerve X), which innervates most thoracic and abdominal organs. Sacral nerves primarily innervate the pelvic organs. Preganglionic neurons: … Read more

Structure of the Sympathetic Nervous System (SNS) The sympathetic nervous system (SNS) originates from the thoracolumbar region of the spinal cord (T1-L2). Its nerve fibers arise from neurons in the lateral horn of the spinal cord. Preganglionic neurons: These are shorter neurons that exit the spinal cord and travel to a sympathetic ganglion (a cluster … Read more

Classification of the Peripheral Nervous System includes the somatic and autonomic systems, controlling voluntary and involuntary body functions. The Peripheral Nervous System (PNS) is one of the two major components of the nervous system, the other being the Central Nervous System (CNS). The PNS consists of all the nerves that lie outside the brain and … Read more

The limit test for sulfate is a qualitative test that detects whether the sulfate ion (SO₄²⁻) concentration in a sample is below a predefined acceptable limit. It is based on the precipitation reaction between barium ions (Ba²⁺) and sulfate ions (SO₄²⁻), forming an insoluble white precipitate of barium sulfate (BaSO₄). Chemical Reaction: Ba2+(aq) + SO₄2−(aq) … Read more

The Joint movements allowed by synovial joints can be classified into several categories: Gliding, Angular, Rotational & Special Movements 1) Gliding Movements Simple sliding motion between flat bone surfaces. Example: Intercarpal joints in the wrist. 2) Angular Joint Movements Types: Flexion: Decreasing the angle between two bones. Example: Bending the elbow. Extension: Increasing the angle between … Read more

Functional classification of joints is based on the degree of movement allowed by the joint. There are three primary functional classification of joints: 1) Synarthrosis (Immovable Joints) These joints allow little or no movement. Example: Sutures of the skull. 2) Amphiarthrosis (Slightly Movable Joints) These joints permit limited movement. Example: The pubic symphysis and intervertebral … Read more

The structural classification of joints is based on the material that binds the bones together and whether or not a joint cavity is present. There are three primary structural classification of joints: 1) Fibrous Joints These joints are connected by dense connective tissue, primarily composed of collagen. They do not have a joint cavity. Types: … Read more

A neuromuscular junction (NMJ) is the synapse or connection between a motor neuron and a muscle fiber. It is a specialized structure that enables the transmission of electrical signals from the nervous system to the muscle, resulting in muscle contraction. Components of the Neuromuscular Junction 1) Presynaptic Terminal Location: The axon terminal of the motor … Read more

Muscle contraction is a complex process that involves the interaction of myofilaments (actin and myosin) within muscle fibers, leading to muscle shortening and force generation. The process can be broken down into four key steps: neuromuscular transmission, excitation-contraction coupling, cross-bridge cycling, and muscle relaxation. Neuromuscular Transmission Action Potential Initiation: Muscle contraction begins with an action … Read more