Tissue Organization and ECM Overview

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Questions and Answers

Which level of tissue organization is characterized by cells being composed of various molecules?

Tissue level

System level

Chemical level

Cellular level (correct)

What role does the extracellular matrix play in tissue functionality?

It serves as the primary site for cellular respiration.

It solely composes blood vessels in tissues.

It provides energy for cell metabolism.

It influences the structure and function of the tissue type. (correct)

Which molecule in the extracellular matrix is primarily responsible for providing strength and structure?

Proteoglycans

Elastin

Collagen (correct)

Integrins

What property does elastin contribute to the extracellular matrix?

Elasticity and stretchiness Signup and view all the answers

Which type of tissue includes nerve cells that provide sensation?

Nervous tissue Signup and view all the answers

Which component of the extracellular matrix is essential for attracting water and contributes to the softness of tissues?

Proteoglycans Signup and view all the answers

What type of connective tissue mainly fills spaces and provides structural support in the skin?

Loose connective tissue Signup and view all the answers

Which characteristic best describes integrins in the context of the extracellular matrix?

They are responsible for cellular adhesion. Signup and view all the answers

Which of the following accurately describes immature bone?

It is found during fracture repair and fetal growth. Signup and view all the answers

What is a characteristic of mature bone?

It contains osteocytes housed in lacunae. Signup and view all the answers

During which process does woven bone remodel into mature bone?

The remodeling process due to the application of stressors. Signup and view all the answers

Which factor does NOT influence the duration of fracture healing?

Presence of scar tissue. Signup and view all the answers

Which of the following cell types is NOT involved in the initial phase of fracture repair?

Osteoblasts. Signup and view all the answers

What role do Haversian canals play in mature bone?

They contain the blood and lymphatic vessels. Signup and view all the answers

During which stage of fracture healing does the hematoma form?

During the inflammatory phase. Signup and view all the answers

Which of the following is true regarding neovascularization in fracture healing?

It refers to the formation of new blood vessels. Signup and view all the answers

What characterizes transudate fluid?

Low protein content and minimal cellular content Signup and view all the answers

What is the major goal of vascular alterations during inflammation?

Increase movement of plasma proteins and circulating cells to the site of injury Signup and view all the answers

What condition can lead to decreased fluid reabsorption due to increased venous resistance?

Blood clots Signup and view all the answers

Which of the following is an example of a condition that slows or stops lymphatic flow?

Mastectomy Signup and view all the answers

Which of the following best describes the process of diapedesis?

Leukocytes migrating out of the blood vessel into interstitial space Signup and view all the answers

During inflammation, what effect does vasodilation initially have on blood flow?

Increases blood flow to the affected area Signup and view all the answers

What differentiates pitting edema from non-pitting edema?

Pitting edema involves free fluid accumulation in the interstitial space. Signup and view all the answers

Why do veins have greater distensibility compared to arteries?

Veins have thinner walls, allowing them to expand more. Signup and view all the answers

What is the role of chemotaxis in the inflammatory response?

Promotes the migration of leukocytes towards the site of inflammation Signup and view all the answers

What is the primary mechanism responsible for the formation of pitting edema?

Free fluid accumulation in the interstitium. Signup and view all the answers

How do lymphatic vessels contribute to the inflammatory response?

They drain exudate and reduce edema Signup and view all the answers

What is the process of margination in the context of inflammation?

Engorgement and slow flow of blood leading to leukocyte accumulation Signup and view all the answers

What is the primary role of veins in the circulatory system?

Act as a blood reservoir. Signup and view all the answers

What is a key function of leukocytes during inflammation?

Release growth factors for healing Signup and view all the answers

What does the relationship between volume and pressure in the arterial system indicate?

Pressure increases as volume increases. Signup and view all the answers

Which of the following best explains why edema occurs?

Accumulation of fluid in the interstitial space. Signup and view all the answers

What is the main effect of small changes in blood volume on arterial pressure?

It causes a significant increase in arterial pressure. Signup and view all the answers

How do large changes in blood volume affect venous pressure?

They have little effect on venous pressure. Signup and view all the answers

What role does aortic distensibility play during cardiac diastole?

It allows for continuous blood movement due to elastic recoil. Signup and view all the answers

What defines pulse pressure?

The difference between systolic and diastolic arterial pressure. Signup and view all the answers

What does a high pulse pressure indicate clinically?

It signifies a large difference between systolic and diastolic pressure. Signup and view all the answers

What is typically the cause of a low pulse pressure, referred to as a 'thready' pulse?

Low systolic pressure. Signup and view all the answers

Which of the following scenarios would contribute to a high pulse pressure?

Elevated systolic pressure combined with low diastolic pressure. Signup and view all the answers

During systole, what happens to the aorta?

The aorta expands and fills with blood. Signup and view all the answers

Study Notes

Tissue Organization Hierarchy

Chemical Level: Atoms combine to form molecules.
Cellular Level: Cells are composed of various molecules.
Tissue Level: Tissues are composed of cells and the extracellular matrix (ECM) they produce.
System Level: Systems are formed by different tissues types working together.
- For example, the skin system includes the epidermis (epithelial tissue), dermis (connective tissue), blood vessels (epithelial and connective tissue), and nerves (nervous tissue).

Extracellular Matrix (ECM)

ECM is comprised of fluids and molecules secreted by cells.
The ECM influences the structure and function of the tissue.
- For example, the ECM of bone cells makes bone rigid, while the ECM of tendon cells makes tendons stretchy.

Major ECM Molecules

Collagen: Provides structure and strength, has a triple helix structure.
Elastin: Provides elasticity (stretchiness).
Proteoglycans: Fill space and attract water, influencing tissue softness.
- Cartilage has numerous proteoglycans, providing cushioning.
Integrins: Act as "glue" connecting cells to each other and to other ECM components.

Bone Tissue Types

Immature Bone (Woven Bone):
- Also known as "primary bone".
- Found during fracture repair and fetal growth.
- Weaker than mature bone due to irregular collagen structure and less mineral content.
Mature Bone (Lamellar Bone):
- Also known as "secondary bone".
- Forms during remodeling of woven bone.
- Stronger than woven bone.
- Osteon structure: Concentric rings adapted to stressors, with osteocytes housed in lacunae.
- Haversian canals: Contain blood vessels and lymphatics.
- Volkmann's canals: Connect osteons together.
- More mineral content in osteoid than woven bone.

Fracture Repair

Healing occurs through regeneration and remodeling, aiming for scar-free restoration and optimal function.
Duration depends on factors like fracture site, type, treatment, soft tissue involvement, and individual factors such as age, immune status, and nutrition.
Phases of healing:
- Internal bleeding: Cells (fibroblasts, platelets, osteoprogenitor cells, mesenchymal cells, inflammatory cells) are delivered to the site, secreting growth factors.
- Hematoma formation: Lasts about a week.
- Inflammation: Granulation tissue (fibrosis and neovascularization) forms.

Vascular Alterations in Inflammation

Goal of vascular alterations is to increase movement of plasma proteins and cells from the blood to the injury site ("exudation").
Increased capillary permeability: Inter-endothelial spaces widen, allowing fluid and protein leakage.
Vasodilation: Increased blood flow to the injured area initially.
Decreased blood flow: After fluid leakage, increased blood viscosity occurs, leading to reduced flow.
Fluid clotting: Increased fibrinogen leads to clotting.
Leukocyte migration and accumulation: They destroy pathogens, release toxins, clean up debris through phagocytosis, and release growth factors for healing.

Leukocyte Role in Inflammation

Removal of injurious stimulus: Destroy pathogens and remove debris.
Release of toxic substances: Inactivate and degrade pathogens.
Phagocytosis: Clean up the area of debris.
Growth factor release: Promote healing and regeneration.

Leukocyte Movement in Inflammation

Stasis: Engorgement of blood vessels slows blood flow.
Margination: Leukocytes accumulate along the endothelial cells of blood vessel walls due to adhesion molecules.
Diapedesis: Leukocytes actively migrate out of the blood vessel, squeezing between endothelial cells, to reach the interstitial space.
Chemotaxis: Chemotactic agents (chemokines) attract leukocytes to the injury site.

Role of the Lymphatic System

Drainage of exudate: Lymphatic vessels remove fluid from the interstitium, reducing edema, removing inflammatory stimuli, and removing leukocytes.
Antigen presentation: Phagocytes present antigens to lymphocytes in lymph nodes, stimulating immune responses.

Edema

Edema: Fluid accumulation in interstitial spaces.
Pitting edema: Excess fluid accumulates, disrupting the gel-like consistency of the interstitial space, forming "puddles". Pressing on pitting edema leaves an indentation after finger removal.

Arterial and Venous Distensibility

Arteries and arterioles: Thicker smooth muscle layers compared to veins.
Veins and venules: Thinner walls, resulting in greater distensibility than arteries.
- Veins can expand more for a given blood pressure, serving as blood reservoirs.

Volume and Pressure Relationship

Arteries: Small changes in volume cause major changes in arterial pressure due to lower distensibility.
Veins: Large changes in volume cause small changes in venous pressure due to higher distensibility.

Aortic Distensibility and Systemic Circulation

Systole: Blood fills the aorta and causes distension.
Diastole: Aorta recoils, applying inward pressure against the blood, driving flow to areas of lower pressure and ensuring continuous blood flow during cardiac relaxation.

Pulse Pressure

Definition: Difference between systolic and diastolic arterial blood pressure.
"Bounding" pulse: High pulse pressure, potentially indicating high systolic pressure, elevated systolic and diastolic pressure (hypertension), or normal systolic pressure with low diastolic pressure.
"Thready" pulse: Low pulse pressure, most likely caused by low systolic pressure.

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Description

Explore the hierarchical organization of tissues from chemical to system levels. Understand the role of the extracellular matrix (ECM) in tissue structure and function along with its major molecules like collagen and elastin.