Histology and Embryology Chapter 2

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Questions and Answers

Which type of tissue covers and lines the external and internal body surfaces?

Connective tissue

Muscle tissue

Epithelial tissue (correct)

Nerve tissue

What characterizes simple epithelium?

Composed of a single layer of cells (correct)

Is primarily made of connective tissue

Contains tightly packed polyhedral cells

Consists of multiple layers

What is the basic function of the basement membrane?

To facilitate muscle contraction

To provide nerve signaling

To support and anchor the epithelium (correct)

To store fat in connective tissue

What is the characteristic of stratified epithelium?

Two or more layers of cells, with only the lower layer contacting the basement membrane Signup and view all the answers

How do epithelial cells obtain their nutrition?

By diffusion from adjoining connective tissue Signup and view all the answers

Which of the following statements about epithelial tissue is incorrect?

It has low cellular turnover. Signup and view all the answers

What type of cartilage is characterized by the presence of numerous elastic fibers in addition to collagen fibers?

Elastic cartilage Signup and view all the answers

Which cells are responsible for producing the cartilage matrix?

Chondroblasts Signup and view all the answers

Which type of cartilage is rarely found alone and often merges with neighboring hyaline cartilage?

Fibrocartilage Signup and view all the answers

What is the main function of cartilage in the embryo?

To serve as a temporary skeletal framework Signup and view all the answers

What is interstitial growth in cartilage?

Growth from deep within the tissue Signup and view all the answers

Which of the following statements about bone tissue is true?

It constitutes most of the mature skeleton. Signup and view all the answers

What is the role of osteoblasts in bone tissue?

To form new bone Signup and view all the answers

What characterizes compact bone compared to cancellous bone?

It is heavier with few tissue spaces. Signup and view all the answers

What type of growth occurs in cartilage when layers are added from the outside of the tissue mass?

Appositional growth Signup and view all the answers

What is the role of osteoblasts in bone histology?

They produce the bone matrix in the form of osteoid. Signup and view all the answers

Which cells are considered mature osteoblasts that are trapped in the bone matrix?

Osteocytes Signup and view all the answers

What is the primary function of blood as a connective tissue?

To serve as a transport medium for cellular nutrients. Signup and view all the answers

Which component of blood is primarily responsible for carrying proteins and cells?

Plasma Signup and view all the answers

What occurs to serum after clotting proteins are removed?

It remains a fluid substance derived from plasma. Signup and view all the answers

Which formed element of blood is primarily responsible for transporting oxygen and carbon dioxide?

Red Blood Cells Signup and view all the answers

What is the primary function of platelets in the blood?

Clotting mechanism Signup and view all the answers

Which type of muscle tissue is involuntary and found in the heart?

Cardiac Muscle Signup and view all the answers

Which of the following statements about white blood cells is true?

They have a nucleus and are involved in immune responses. Signup and view all the answers

How are red blood cells characterized?

Bi-concave discs without a nucleus Signup and view all the answers

What type of muscle tissue is voluntarily controlled and usually attaches to bones?

Skeletal Muscle Signup and view all the answers

Which component of blood is derived from stem cells in the bone marrow?

All formed elements of blood Signup and view all the answers

Which of the following best describes the structural organization of skeletal muscle?

Made up of fascicles composed of myofibrils and myofilaments Signup and view all the answers

What marks the end of the preimplantation period?

Implantation in the uterine lining Signup and view all the answers

Which layer of the blastocyst is responsible for forming the embryo?

Embryoblast layer Signup and view all the answers

During which week does the primitive streak begin to form?

3rd week Signup and view all the answers

What is the result of increased cellular proliferation during the embryonic period?

Development of trilaminar disc Signup and view all the answers

What does the mesenchyme develop into during the embryonic period?

Mesoderm Signup and view all the answers

The blastocyst consists of which two main layers?

Trophoblast and embryoblast Signup and view all the answers

What initiates the CNS development in the later part of the 3rd week?

Differentiation of ectoderm into neuroectoderm Signup and view all the answers

What is the correct sequence of structures formed from ectoderm during neural development?

Neural plate -> neural groove -> neural fold -> neural tube Signup and view all the answers

Study Notes

Tissue Histology

Tissues are classified into four basic histological types: epithelial, connective, muscle, and nerve.

Epithelial Tissue

Epithelium covers and lines body surfaces, including vessels and cavities.
Composed of closely packed polyhedral cells with minimal intercellular substance.
Cells are tightly joined by desmosomes and hemidesmosomes, with no blood vessels (avascular).
Nutrients diffuse from adjoining connective tissue, and rapid cellular turnover occurs.

Classification of Epithelial Tissues

Simple Epithelium: Single layer of cells.
Stratified Epithelium: Two or more layers; only the basal layer contacts the basement membrane.
Predominantly stratified squamous epithelium in the body.

Rete Ridges

Extensions of epithelium into connective tissue known as rete ridges or rete pegs.

Basement Membrane

Thin acellular layer between epithelium and connective tissue.
Composed of two layers: basal lamina (superficial) and deeper loose connective tissue.

Connective Tissue: Cartilage

Firm, non-calcified tissue that acts as skeletal support, especially in embryos and joints.
Avascular tissue relies on neighboring connective tissues (perichondrium) for nutrition.
Contains no nerve supply.

Histology of Cartilage

Composed of chondroblasts (cartilage matrix producers) and chondrocytes (mature chondroblasts).
Three types of cartilage:
- Hyaline Cartilage: Most common, contains only collagen fibers.
- Elastic Cartilage: Contains elastic fibers in addition to collagen.
- Fibrocartilage: Merges with hyaline cartilage and is never found alone.

Cartilage Growth

Grows via:
- Interstitial Growth: From within the tissue.
- Appositional Growth: Addition of layers from the outer surface.

Connective Tissue: Bone

Rigid tissue forming most of the mature skeleton.
Covered by periosteum, which has an outer layer (blood vessels and nerves) and an inner layer (osteoblasts).

Types of Bone

Compact Bone (Cortical): Dense with few spaces.
Cancellous Bone (Spongy/Trabecular): Lightweight with many tissue spaces.
Endosteum: Inner lining of bones, similar to periosteum but thinner.

Histology of Bone

Bone matrix initially forms as osteoid produced by osteoblasts.
Osteocytes: Mature osteoblasts trapped in bone matrix; Osteoclasts: Cells responsible for bone resorption.

Connective Tissue: Blood

Fluid connective tissue that transports cellular nutrients.
Composed of plasma and formed elements, with plasma being the liquid component.
Serum: Fluid remaining after clotting proteins are removed.

Formed Elements of Blood

Red Blood Cells (RBCs): Biconcave disc, no nucleus; contains hemoglobin for oxygen and carbon dioxide transport.
Platelets (Thrombocytes): Cell fragments, involved in blood clotting.
White Blood Cells (WBCs): Defense cells, critical for inflammatory and immune responses.

Muscle Tissue

Comprises the muscular system; muscles contract under neural control causing movement.
Three types of muscle tissue:
- Smooth Muscle: Involuntary, located in organs and blood vessel linings.
- Cardiac Muscle: Involuntary, forms the heart's wall.
- Skeletal Muscle: Voluntary, usually attached to bones.

Histology of Skeletal Muscle

Striated muscles composed of numerous fascicles, which contain myofibers made of myofibrils and myofilaments.

Nerve Tissue

Nerves consist of bundles of neural processes outside the central nervous system (CNS) and function to transmit electrical impulses.

Embryology

Preimplantation Period:
- Occurs in the first week; fertilization forms a zygote which undergoes mitosis to become a blastocyst.
Embryonic Period:
- Begins at implantation (2nd-8th week); blastocyst differentiates into trophoblast (placenta) and embryoblast (embryo).
- Formation of the bilaminar disc: epiblast (amniotic cavity side) and hypoblast (yolk cavity side).

Trilaminar Disc Development

Primitive streak formation leads to mesoderm development, adding a third layer to form a trilaminar disc: ectoderm, mesoderm, endoderm.
In the late 3rd week, the central nervous system (CNS) begins to develop from neuroectoderm, forming the neural structures.

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Description

Explore the fundamental concepts of tissue histology in this quiz based on Chapter 2 of Histology and Embryology. Learn about the four basic histological types: epithelial, connective, muscle, and nerve tissues. Test your knowledge on the characteristics and functions of epithelial tissue and its role in covering and lining body surfaces.