Test II: Connective Tissue Flashcards by Vivian Caloobanan

Characteristics of Connective Tissue

Specialized cells
Solid extracellular protein fibers
Fluid extracellular ground substance

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The Extracellular Components of Connective

Tissue (Fibers and Ground Substance)

– Make up the matrix
• Majority of tissue volume
• Determines specialized function

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Functions of Connective Tissue

– Establishing a structural framework for the body
– Transporting fluids and dissolved materials
– Protecting delicate organs
– Supporting, surrounding, and interconnecting
other types of tissue
– Storing energy reserves, especially in the form of
triglycerides
– Defending the body from invading
microorganisms

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Classification of Connective Tissues

1. Connective tissue proper
• Connect and protect
2. Fluid connective tissues
• Transport
3. Supporting connective tissues
• Structural strength

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The most abundant connective cell type
• Found in all connective tissue proper
• Secrete proteins and hyaluronan (cellular cement)

Fibroblasts

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The second most abundant cell type
• Found in all connective tissue proper
• Maintain the fibers of connective tissue proper

Fibrocytes

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Fat cells
• Each cell stores a single, large fat droplet
do not divide (hypertrophy only)
– Expand to store fat
– Shrink as fats are released

Adipocytes

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Stem cells that respond to injury or infection
• Differentiate into fibroblasts, macrophages, etc.
divide and differentiate (hyperplasia)
– To produce more fat cells
– When more storage is needed

Mesenchymal Cells

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Large, amoeba-like cells of the immune
system
• Eat pathogens and damaged cells

Macrophages
• Fixed macrophages stay in tissue
• Free macrophages migrate

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Stimulate inflammation after injury or infection

• Release histamine and heparin

Mast Cells

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leukocytes (white blood cells)

that also contain histamine and heparin

Basophils

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Specialized immune cells in lymphatic

(lymphoid) system

Lymphocytes

For example, lymphocytes may develop into plasma cells (plasmocytes) that produce antibodies

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Phagocytic blood cells
• Respond to signals from macrophages and mast
cells
• For example, neutrophils and eosinophils

Microphages

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Synthesize and store the brown pigment

melanin

Melanocytes

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2 types of adipose tissue

White fat

2. Brown fat

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Type of fat that is
– Most common
– Stores fat
– Absorbs shocks
– Slows heat loss (insulation)

White fat

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Type of fat that is
– More vascularized
– Adipocytes have many mitochondria
– When stimulated by nervous system, fat breakdown
accelerates, releasing energy
– Absorbs energy from surrounding tissues

Brown fat

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Functions of adipose tissue

Provides padding and cushions shocks; insulates

(reduces heat loss); stores energy

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Tightly packed, parallel collagen fibers

Dense Regular Connective Tissue

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Types of Dense Regular Connective Tissue

tendons
ligaments
aponeuroses

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attach muscles to bones

Tendons

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connect bone to bone and stabilize

organs

Ligaments

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attach in sheets to large, flat

muscles

Aponeuroses

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Functions of dense regular connective tissue

Provides firm attachment; conducts pull of muscles; reduces friction between muscles; stabilizes relative positions of bones

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``` – Interwoven networks of collagen fibers • Layered in skin • Around cartilages (perichondrium) • Around bones (periosteum) • Form capsules around some organs (e.g., liver, kidneys) ```

Dense Irregular Connective Tissue

Functions of Dense Irregular Connective Tissue

Provides strength to resist forces applied from many directions; helps prevent overexpansion of organs such as the urinary bladder

Locations of dense, irregular connective tissue

Capsules of visceral organs; periostea | and perichondria; nerve and muscle sheaths; dermis

Fluid Connective Tissues

– Blood and lymph – Watery matrix of dissolved proteins – Carry specific cell types (formed elements)

Fluid Elements of Connective Tissues

– Extracellular • Plasma • Interstitial fluid • Lymph

are responsible for the transport of oxygen | (and, to a lesser degree, of carbon dioxide) in the blood.

RBC's

help defend the body from infection and disease.

White blood cells, or leukocytes

membrane-enclosed packets of cytoplasm that function in blood clotting; These cell fragments are involved in the clotting response that seals leaks in damaged or broken blood vessels.

Platelets

``` Extracellular fluid • Collected from interstitial space • Monitored by immune system • Transported by lymphatic (lymphoid) system • Returned to venous system ```

Lymph

Supporting Connective Tissues

Bone and cartilage

* Gel-type ground substance | * For shock absorption and protection

Cartilage

* Calcified (made rigid by calcium salts, minerals) | * For weight support

Bone

Bone contains four types of cells

1. Osteocytes 2. Osteoblasts 3. Osteoprogenitor cells 4. Osteoclasts

– Mature bone cells that maintain the bone matrix – Are between layers (lamellae) of matrix – Connect by cytoplasmic extensions through canaliculi in lamellae – Do not divide

Osteocytes

Two major functions of osteocytes

1. To maintain protein and mineral content of matrix | 2. To help repair damaged bone

– Immature bone cells that secrete matrix | compounds (osteogenesis)

Osteoblasts (Osteoblasts surrounded by bone become osteocytes)

matrix produced by osteoblasts, | but not yet calcified to form bone

Osteoid

``` – Mesenchymal stem cells that divide to produce osteoblasts – Located in endosteum, the inner cellular layer of periosteum – Assist in fracture repair ```

Osteoprogenitor Cells

– Secrete acids and protein-digesting enzymes – Giant, multinucleate cells – Dissolve bone matrix and release stored minerals (osteolysis) – Derived from stem cells that produce macrophages

Osteoclasts

The Structure of Spongy Bone

– The matrix forms an open network of trabeculae – Trabeculae have no blood vessels – The space between trabeculae is filled with red bone marrow

Red bone marrow

* Which has blood vessels * Forms red blood cells * And supplies nutrients to osteocytes

Yellow bone marrow

• In some bones, spongy bone holds yellow bone marrow • Is yellow because it stores fat

Bone Development

– Human bones grow until about age 25

Bone formation

Osteogenesis

The process of replacing other tissues with bone

Ossification

The process of depositing calcium salts

Calcification

Epiphyseal Lines

– When long bone stops growing, after puberty: • Epiphyseal cartilage disappears • Is visible on X-rays as an epiphyseal line

Mature Bones

As long bone matures: • Osteoclasts enlarge medullary (marrow) cavity • Osteons (compact bone) form around blood vessels

Process of Remodeling

``` – The adult skeleton: • Maintains itself – Replaces mineral reserves • Recycles and renews bone matrix • Involves osteocytes, osteoblasts, and osteoclasts ```

Effects of Exercise on Bone

Mineral recycling allows bones to adapt to stress – Heavily stressed bones become thicker and stronger

Bone Degeneration

– Bone degenerates quickly – Up to one third of bone mass can be lost in a few weeks of inactivity

Hormone Calcitriol

• Made in the kidneys • Helps absorb calcium and phosphorus from digestive tract • Synthesis requires vitamin D3 (cholecalciferol)

Hormone that stimulates bone growth

Growth hormone and thyroxine

Hormone that stimulates osteoblasts

Estrogens and androgens

Hormone that regulates calcium and phosphate levels

Calcitonin and parathyroid hormone

Calcitonin and Parathyroid Hormone | Control

``` – Affect: 1. Bones – Where calcium is stored 2. Digestive tract – Where calcium is absorbed 3. Kidneys – Where calcium is excreted ```

Know responses when calcium levels are low or high

Slides

Test II: Connective Tissue Flashcards

(61 cards)