Connective Tissue - Bone Study Guide

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Questions and Answers

What differentiates mature bone from woven bone?

Mature bone lacks Haversian canals

Mature bone contains fewer osteocytes

Mature bone has lower mineral content in osteoid

Mature bone has a less irregular collagen structure (correct)

Which factor does NOT influence the duration of fracture healing?

Economical status (correct)

Soft tissue involvement

Fracture type

Age of the individual

Which of the following best describes the structure of mature bone?

Concentric rings forming osteons (correct)

Randomly distributed osteocytes

Irregular arrangement of osteons

Absence of Haversian canals

What occurs during the inflammatory phase of fracture healing?

Formation of granulation tissue Signup and view all the answers

Which cell type can become osteoblasts during fracture repair?

Mesenchymal cells Signup and view all the answers

What is a key characteristic of lamellar bone?

It has a more organized structure Signup and view all the answers

What role do osteoprogenitor cells play in fracture healing?

They can transform into osteoclasts Signup and view all the answers

Which process contributes to the remodeling of woven bone into mature bone?

Adaptation based on applied stressors Signup and view all the answers

What is the primary role of osteoclasts in bone tissue?

To break down the extracellular matrix Signup and view all the answers

Which component of bone is primarily responsible for its non-mineralized aspects?

Osteoid Signup and view all the answers

What characterizes the cortical bone in terms of its structure?

It is the majority type of bone in the body Signup and view all the answers

Which of the following statements about osteoblasts is true?

They secrete the extracellular matrix that gives bone its properties Signup and view all the answers

Which term refers to the type of bone found during fracture repair and fetal growth?

Woven bone Signup and view all the answers

What is the primary mineralized component of bone?

Hydroxyapatite Signup and view all the answers

What separates osteocytes from other bone cells?

They maintain the extracellular matrix Signup and view all the answers

Which of the following is not a function attributed to bone lining cells?

Secrete the extracellular matrix Signup and view all the answers

Which level of tissue organization is composed of a variety of tissue types working together?

System level Signup and view all the answers

What best describes the primary function of the extracellular matrix?

Influencing the physical properties and functionality of the tissue Signup and view all the answers

What is a significant characteristic of loose connective tissue within the dermis?

It is filled with collagen fibers and provides flexibility Signup and view all the answers

Which statement about epithelial tissue is true within the context of skin anatomy?

It forms the outer protective layer called the epidermis Signup and view all the answers

How do the extracellular matrix components vary between bone and tendon tissues?

Bone provides rigidity, while tendons offer elasticity Signup and view all the answers

Which component of skin primarily supplies nutrients to the cells in the epidermis?

Connective tissue (blood) Signup and view all the answers

What is the primary purpose of the extracellular matrix produced by bone cells?

To ensure hardness and rigidity of bone tissue Signup and view all the answers

What tissue type is characterized by having specialized cells for sensation in skin?

Nervous tissue Signup and view all the answers

Which of the following genetic alterations is most directly associated with Down's syndrome?

Alterations in structure/number of chromosomes Signup and view all the answers

What is a potential consequence of increased sodium and calcium influx into a cell?

Decreased ATP production Signup and view all the answers

What is a primary characteristic of reactive oxygen species (ROS)?

They have unpaired electrons and can react with various molecules. Signup and view all the answers

Which response to chronic cellular stress involves an increase in the size of cells?

Hypertrophy Signup and view all the answers

Which of the following factors contributes to oxidative stress?

Excessive exercise beyond personal limits. Signup and view all the answers

Which type of mechanical stressor does NOT belong in the category of those that can initiate a cellular response?

Anoxia Signup and view all the answers

How do antioxidants function in cellular health?

They neutralize reactive oxygen species to prevent cellular damage. Signup and view all the answers

What must occur for reversible cell injury to take place?

Energy source must be restored Signup and view all the answers

What is one of the implications of excessive oxidative stress?

It contributes to several lifestyle disease processes. Signup and view all the answers

What defines the relationship between exercise and reactive oxygen species formation?

Exercise can increase ROS formation acutely. Signup and view all the answers

Which condition is an example of a disease caused by single mutations in genes affecting protein expression?

Sickle cell anemia Signup and view all the answers

Which of the following is NOT a possible response to physical stress?

Genetic mutation Signup and view all the answers

Which of the following is NOT an endogenous antioxidant?

Vitamin E Signup and view all the answers

Which factor does NOT influence the likelihood of cellular injury reversal?

Type of tissue affected. Signup and view all the answers

Which response to chronic cellular stress results in an increase in the number of cells?

Hyperplasia Signup and view all the answers

What is an outcome of increased ROS formation from exercise?

Impaired muscle recovery and adaptation. Signup and view all the answers

What is the primary function of collagen in the extracellular matrix?

Provides structure and strength Signup and view all the answers

Which component of the extracellular matrix is primarily responsible for the elasticity of tissues?

Elastin Signup and view all the answers

What role do proteoglycans play in the extracellular matrix?

Fill space and retain water Signup and view all the answers

What is a defining characteristic of epithelial tissue?

Protection and lining of organs Signup and view all the answers

Which type of connective tissue is essential for structural support?

Cartilage Signup and view all the answers

Which type of muscle tissue is not under voluntary control?

Smooth muscle Signup and view all the answers

What is the main function of fibroblasts in connective tissue?

Produce collagen and elastin Signup and view all the answers

What are integrins known to do in the extracellular matrix?

Connect cells to each other and to matrix proteins Signup and view all the answers

What is the primary feature that distinguishes hypertrophy from hyperplasia?

Hypertrophy involves an increase in cell size. Signup and view all the answers

In which scenario would you most likely observe dysplasia?

Chronic irritation leading to abnormal cell organization. Signup and view all the answers

Which of the following correctly describes metaplasia?

Replacement of one type of cell with another type. Signup and view all the answers

Which example best illustrates hyperplasia?

Thickened uterine wall lining due to estrogen exposure. Signup and view all the answers

What condition exemplifies irreversible cell injury?

Necrosis characterized by cell swelling and inflammation. Signup and view all the answers

Which type of tissue response is characterized by increased cell size due to functional demands?

Hypertrophy. Signup and view all the answers

Which of the following describes the outcome of atrophy?

Reduction in size of an organ or tissue. Signup and view all the answers

What is a physiological example of hypertrophy?

Increase in cardiac muscle mass due to exercise. Signup and view all the answers

Study Notes

General Structure of Bone

Cortical Bone (Compact Bone): Tough outer layer; constitutes the majority of bone mass; covered by periosteum rich in blood vessels.
Cancellous Bone (Trabecular or Spongy Bone): Features spongy, mesh-like plates; in direct contact with bone marrow.

Cellular and Non-cellular Components of Bone

Cellular Component:
- Osteoblasts: Immature bone cells responsible for secreting the extracellular matrix; can differentiate into osteocytes, bone lining cells, or undergo apoptosis.
- Osteocytes: Mature bone cells that maintain the extracellular matrix and respond to mechanical loading and hormonal changes.
- Osteoclasts: Responsible for breaking down the extracellular matrix, releasing minerals into the bloodstream, and creating space for osteoblast activity.
- Bone Lining Cells: Play a role in maintaining the bone surface.
Non-cellular Component:
- Non-mineralized Matrix: Known as osteoid; primarily consists of collagen.
- Mineralized Matrix: Composed chiefly of hydroxyapatite, providing rigidity.

Classifications of Bone Maturity

Immature Bone (Woven Bone):
- Also referred to as primary bone; typically found during fracture repair and fetal development; characterized by irregular collagen structure and lower mineral content, making it weaker.
Mature Bone (Lamellar Bone):
- Known as secondary bone; results from the remodeling of woven bone under stress; exhibits an organized osteon structure with concentric rings, providing greater strength and higher mineral content.
Bone Types: Both cortical and cancellous bones can present in immature forms.

Process of Fracture Repair

Regeneration and Remodeling: Repair process aims to restore optimal bone function without forming scars.
Healing Duration: Influenced by factors such as fracture site, type, treatment, soft tissue involvement, and individual traits (age, immune health, nutritional status).
Phases of Healing:
- Initial Response: Internal bleeding leads to cell influx at injury site, secreting growth factors and facilitating clot formation (involves fibroblasts, platelets, osteoprogenitor cells, and inflammatory cells).
- Hematoma Formation: Develops and persists for about a week post-injury.
- Inflammatory Phase: Formation of granulation tissue, including fibrosis and neovascularization (new blood vessel formation).

Tissue Types

Tissue organization hierarchy: chemical level → cellular level → tissue level → system level.
Extracellular matrix (ECM) consists of fluids and molecules secreted by cells, influencing tissue structure and function.
Common ECM molecules:
- Collagen: Provides structure and strength; has a triple helix structure.
- Elastin: Allows elasticity in tissues.
- Proteoglycans: Fill space and attract water, crucial for tissue softness (e.g., cartilage).
- Integrins: Connect cells to other cells and ECM components.

Categories of Tissue

Epithelial Tissue: Protects, lines organs, and produces secretions (e.g., skin, mucous).
Connective Tissue: Fills spaces, provides support (e.g., bone, cartilage), and stores energy (e.g., adipose).
- Fibroblasts are key cells producing ECM components and aiding tissue repair.
Muscle Tissue: Contracts for movement; includes skeletal (voluntary), smooth (involuntary), and cardiac muscles.
Nervous Tissue: Transmits electrical impulses for communication throughout the body.

Cellular Injury / Adaptation

Factors influencing injury reversal: mechanism, duration, and severity of injury.
Free Radical Theory: Reactive oxygen species (ROS) can damage cells; excess ROS leads to oxidative stress, implicated in many diseases.
Antioxidants neutralize ROS, preventing DNA and cell damage.
- Endogenous antioxidants: e.g., glutathione, peroxidase, catalase.
- Exogenous antioxidants: e.g., vitamins C, E, beta-carotene.
Exercise generates ROS but also encourages the development of endogenous antioxidants; excessive exercise can induce oxidative stress.

Genetic Alterations

Genetic changes causing injury:
- Chromosomal abnormalities (e.g., Down's syndrome).
- Single gene mutations affecting protein function (e.g., sickle cell anemia).
- Multi-gene interactions with environmental factors (e.g., Type II diabetes, obesity).

Cellular Responses to Physical Stress

Possible responses include:
- Atrophy: Decreased stress tolerance; examples include muscle and bone loss.
- Maintenance of current state.
- Hypertrophy: Increased cell size due to demands or hormonal input; occurs in cardiac and skeletal muscles, e.g., left ventricular hypertrophy.
- Hyperplasia: Increased cell number often from hormonal or physical stimulation; examples include callus formation and smooth muscle proliferation.
- Injury and Death occur under severe stress.

Reversible Cellular Injury

Process involves:
- Increased sodium and calcium in cells leading to swelling.
- Impaired organelle function, particularly mitochondria affecting ATP production.
- Successful reversal depends on the nucleus remaining intact, restoring energy sources, and neutralizing toxins.

Chronic Cellular Stress Responses

Responses to chronic stress include:
- Atrophy: Reduction in organ or cell size, e.g., muscle wasting.
- Hypertrophy: Growth in cell size due to demand.
- Hyperplasia: Increase in cell numbers in response to stimulation.
- Metaplasia: Transformation of one cell type to another, e.g., airway epithelium changes in smokers.
- Dysplasia: Increased cell numbers with loss of morphology and organization, often in chronic injury contexts.

Irreversible Cell Injury

Consequences and processes of irreversible injury lead to cell death, characterized by severe damage that cannot be repaired.

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Description

This study guide covers the structure of bone, focusing on cortical and cancellous bone. Learn about the tough outer layer of compact bone and the spongy characteristics of trabecular bone, along with their relationship to blood vessels and bone marrow.