Injury, Inflammation, and Healing: Key Concepts in Tissue Repair

What is an injury?

A stress or force that disrupts the normal homeostasis of a tissue.

What is an acute injury?

An injury caused by a single macrotraumatic event, usually occurring over a short period of time.

What is a chronic injury?

An injury caused by repetitive microtraumatic events.

What is tissue stress?

The force placed on tissues that can cause injury when the stress exceeds the tissue's ability to adapt.

What is strain?

The amount of deformation that occurs in a tissue.

What is plastic deformation?

Permanent deformation of a tissue after the tissue is stressed.

What is mechanical failure?

An injury caused by an inability of a tissue to withstand stress or strain.

What principle states that tissues require stress to remain healthy?

Use it or lose it principle.

What are the three phases of the injury response cycle?

Inflammatory phase, proliferation phase, and maturation phase.

What is the inflammatory phase?

The acute phase of tissue healing that begins immediately after injury.

What is the proliferation phase?

The repair phase in which new tissue is formed.

What is the maturation phase?

The remodeling phase in which tissue is reorganized and strengthened.

What are the four cardinal signs of inflammation?

Redness, heat, swelling, and loss of function.

What causes redness during inflammation?

Vasodilation and increased blood flow.

What causes heat during inflammation?

Increased blood flow and metabolic activity in the injured area.

What causes swelling during inflammation?

Increased vascular permeability and movement of fluid into the tissue.

What causes loss of function during inflammation?

Pain and swelling that limit normal tissue function.

What is norepinephrine's role in inflammation?

It causes vasoconstriction and decreases blood flow.

What is histamine's role in inflammation?

It causes vasodilation and increases cell permeability.

What is vasodilation?

Widening of blood vessels that increases blood flow to the injured area.

What is vasoconstriction?

Narrowing of blood vessels that decreases blood flow.

What is phagocytosis?

The process in which cells engulf and remove damaged tissue and debris.

What is the role of leukocytes in inflammation?

They adhere to vascular walls and help remove damaged tissue and fight infection.

What is the role of prostaglandins in inflammation?

They help with vasodilation and contribute to pain and inflammation.

What is the role of cytokines in inflammation?

They attract phagocytes to the injured area.

What is clot formation's role in healing?

It helps stop bleeding and creates a framework for tissue repair.

What are the three major components involved in clot formation?

Platelets, fibrin, and collagen.

What do platelets do during healing?

They help stop bleeding and begin the repair process.

What does fibrin do during healing?

It forms a mesh that helps hold the clot together.

What does collagen do during healing?

It provides a structural protein framework for the body.

What is granulation tissue?

New tissue that forms during healing and contains new blood vessels and cells.

What is angiogenesis?

The formation of new blood vessels in wounded tissue.

Why is angiogenesis important during healing?

It increases oxygen and blood supply to the injured tissue.

What are the major phases of muscle healing?

Inflammatory phase, proliferation/repair phase, and maturation/remodeling phase.

What is a Grade 1 muscle injury?

A mild muscle injury that generally heals in about 2 weeks.

What is a Grade 2 muscle injury?

A moderate muscle injury that generally heals in about 3 weeks to 3 months.

What is a Grade 3 muscle injury?

A severe muscle injury that can take about 4 weeks to months to heal.

What is the general healing timeline for a tendon?

1st phase about 1-2 days, 2nd phase about 2 days to weeks, and 3rd phase about 2 weeks to 9 months or longer.

What is the function of tendons?

They connect muscle to bone and withstand stress.

What happens to nerves during healing?

Peripheral nervous system cells can undergo different forms of healing depending on the damage to the cell body, nucleus, and axon.

What is metaplasia?

The conversion of one type of tissue into another.

What is dysplasia?

Abnormal development of cells or tissue.

What is hyperplasia?

Proliferation or increase of normal cells in normal arrangement.

What is cartilage's ability to heal?

Cartilage has a limited ability to heal.

Why does cartilage have limited healing?

It has limited blood supply and healing can be poor.

What happens during bone healing in the first 0-2 weeks?

A hematoma forms and bleeding occurs as blood vessels are damaged, followed by formation of a clot.

What happens during bone healing around 2-3 weeks?

A soft callus forms and fibroblasts lay down collagen framework while chondroblasts produce fibrocartilage.

What happens during hard callus formation?

Cartilage is replaced by bone and the area becomes more stable.

What happens during bone remodeling?

Osteoclasts break down and remove bone while osteoblasts lay down new bone.

What factors can impede healing?

Poor vascular supply, edema, separation of tissues, hemorrhage, infection, environment, muscle spasms, atrophy, nutrition, health, and age.

What is a scar?

Connective tissue that forms as part of the healing process.

What are the main types of pain?

Acute pain and chronic pain.

What is acute pain?

Pain that occurs shortly after an injury and generally has a predictable healing pattern.

What is chronic pain?

Pain lasting longer than 6 months that may be related to changes in the nervous system.

What should a patient with pain that does not respond to treatment consider?

Seeking counseling because depression and anxiety can be associated with chronic pain.

What is the gate control theory of pain?

A theory that pain signals can be modified or "gated" in the spinal cord before reaching the brain.

What is an example of a treatment that can affect the gate control mechanism?

Electrical stimulation can help decrease pain.

What is the role of opioids in pain management?

Opioids can reduce the perception of pain by acting on opioid receptors.

What is a nociceptor?

A sensory receptor that detects potentially damaging or painful stimuli.

What do nociceptors detect?

Stimuli such as mechanical, chemical, or thermal damage.

What are A-delta fibers?

Small, myelinated nerve fibers that transmit fast, sharp, localized pain.

What are C fibers?

Small, unmyelinated nerve fibers that transmit slow, dull, generalized pain and temperature.

What are first-order neurons?

Peripheral afferent neurons that carry sensory information toward the spinal cord.

What are second-order neurons?

Neurons that carry sensory information from the spinal cord toward the thalamus.

What are third-order neurons?

Neurons that carry sensory information from the thalamus to the somatosensory cortex.

What is the dorsal horn?

The area of the spinal cord where sensory information enters and is processed.

What is the thalamus' role in pain?

It acts as an important relay station for sensory information before it reaches the cortex.

What is the somatosensory cortex?

The area of the brain that interprets sensory information, including pain.

What is the spinothalamic tract?

A pathway that carries pain and temperature information from the spinal cord toward the brain.

What is the general pathway for pain information?

Nociceptor → peripheral nerve → spinal cord → thalamus → somatosensory cortex.

What is the resting membrane potential?

Approximately -70 mV.

What is the threshold potential?

Approximately -55 mV, the point at which an action potential is triggered.

What is depolarization?

The phase of an action potential in which the membrane potential becomes more positive due primarily to sodium entering the cell.

What is repolarization?

The phase in which the membrane potential returns toward its resting state, primarily due to potassium leaving the cell.

What happens at approximately +30 mV during an action potential?

Sodium channels close/inactivate and potassium channels contribute to repolarization.

What is the refractory period?

The period after an action potential when the neuron cannot immediately generate another normal action potential.

What is the main purpose of an action potential?

To transmit an electrical signal along a nerve cell.

What is the ICF model?

A framework used to describe functioning, disability, activity, participation, and environmental/personal factors.

What does ICF stand for?

International Classification of Functioning, Disability and Health.

What does participation mean in the ICF model?

Involvement in a life situation.

Why is participation important in athletic training?

Participation is more than just treating an injury because an athlete's injury can affect sports, schoolwork, and social life.

What is scope of practice?

The established boundaries within which a healthcare professional is legally allowed to practice.

Why is scope of practice important?

It establishes what services and procedures a professional is legally permitted to perform.

What is licensure?

A legal requirement that allows a healthcare professional to practice within a state.

What is certification?

A credential showing that a professional has met established requirements.

What is registration?

A process of officially recording a professional to practice.

What is exemption?

A situation in which a person or service is not subject to a particular requirement.

What is negligence?

Failure to provide the expected standard of care.

What is malpractice?

Professional negligence or failure to provide the expected level of professional care.

What is misfeasance?

Improperly performing an action that is otherwise legal.

What is malfeasance?

Performing an action that is illegal or wrongful.

What is nonfeasance?

Failure to perform a legal duty or required action.

What are the four elements of negligence?

Duty, breach of duty, causation, and damages.

What is duty?

The legal responsibility to provide appropriate care.

What is breach of duty?

Failure to meet the expected standard of care.

What is causation?

A connection between the breach of duty and the patient's injury.

What are damages?

The measurable harm or loss resulting from an injury.

What is standard of care?

The level of care that a reasonably prudent healthcare professional would provide in a similar situation.

What is standard of practice?

Widely accepted principles used to guide clinical practice.

What is the difference between standard of care and standard of practice?

Standard of care refers to the expected level of care, while standard of practice refers to accepted principles used to guide clinical practice.