A&P - Lesson 6

Connective tissue

most abundant, widely distributed and variable type of tissue where cells occupy less space than the matrix

Characteristic of connective tisse

1. Specialized cells- more than 1 cell type

2. Solid extracellular protein fibers outside

3. Fluid extracellular ground substance

Matrix

Majority of connective tissue volume composed of extracellular components allowing for tissue function

Ground substance

Fills space between cells

Functions of connective tissue

1. Binding of organs

2. Support

3. Physical protection

4. Immune protection

5. Movement

6. Storage

7. Heat production

8. Transport

Mesenchyme

Embryonic connective tissue

What makes mesenchyme special?

It is found in embryos and gives rise to all other connective tissue; adults only have mesenchymal stem cells

Wharton's jelly

Mucous connective tissue found in the embryo; not found in adults

Categories of connective tissue

1. connective tissue proper- connects and protect

2. fluid connective tissue- functions in transportation

3. supporting connective tissue- provides support/strength

Components of fibrous connective tissue/connective tissue proper

1. Fibroblasts

2. Macrophages

3. Leukocytes/WBC

4. Plasma cells

5. Mast cells

6. Adipocyte

fibroblasts

produce fibers and ground substance of the matrix

Macrophages

arise from monocytes; phagocytize foreign material and activate immune system when they sense foreign matter

Leukocytes/White blood cells (WBCs)

function in immune defense

Plasma cells

arise from B lymphocytes and synthesize antibodies

Mast cells

secrete heparin to inhibit clotting and histamine to dilate blood vessels

Adipocytes (fat cells)

clustered in some fibrous tissue; where they dominate is adipose tissue

Heparin

produced by mast cells to inhibit clotting

Histamine

produced by mast cells to dilate blood vessels

Functions of connective tissue proper

1. provide routes for blood/lymphatic vessels and nerves

2. provide strength and stability

3. maintain internal organ position

Fasciae

the body’s framework of connective tissue that wrap, support, or surround organs

3 types of Fasciae

1. Superficial fascia/hypodermis

2. Deep fascia

3. Subserous fascia

Superficial fascia/hypodermis

provides insulation and padding under skin

Deep fascia

• resists force

• creates tendons

• links bones to each other as ligaments

Subserous fascia

protects body cavity lining when muscles/muscular organs move

Adipose tissue

tissue in which adipocytes are the dominant cell with spaces filled with areolar/reticular tissue and capillaries

What is true about fat?

1. Primary energy reservoir

2. Stable in a person

3. Decrease in triglycerides causes adipocytes to shrink

4. Its recycled constantly

white adipose tissue (WAT/white fat)

most abundant and significant type of adipose tissue in adults

Functions of white adipose tissue

1. provides thermal insulation

2. cushions organs (eyeballs, kidneys)

3. contributes to body contours (breasts and hips)

4. secretes hormones that regulate metabolism

Brown adipose tissue

Found in fetuses, infants, and children

What does brown adipose tissue do?

functions as a heat generating tissue

Fluid connective tissue

contains a fluid ground substance (matrix) that suspends a mixture of cells

Blood

contains a cellular component (formed element) and fluid component (blood plasma)

Types of formed elements in blood

1. erythrocytes (red blood cells)

2. leukocytes (white blood cells)

3. platelets

Erythrocytes

transport O2 and CO2

Leukocytes

defend against infection and disease

Platelets

cell fragments involved in blood clotting

Blood smear appearance

• erythrocytes - appear as pale pink discs with light centers

• leukocytes - slightly larger and have variously shaped nuclei

• platelets - small cell fragments with no nuclei

Fluid elements of connective tissue

ECF

Types of ECF

1. plasma

2. interstitial fluid

3. lymph

plasma

matrix component of blood

Interstitial fluid

extracellular fluid surrounding cells

Lymph

leftover ECF that was not reabsorbed back into capillaries collected from interstitial space surrounding cells

Lymphatic system

Drains lymph and monitors for pathogens

Cartilage

• Stiff connective tissue with flexible/rubbery matrix

• gives shape

• avascular

• matrix rich in GAGs

Chondroblasts

Cartilage cells that build the matrix

Chondrocytes

cartilage cells trapped in lacunae cavities of the matrix

types of cartilage

1. hyaline

2. fibrocartilage

3. elastic

anti-angiogenesis

A process or agent that prevents new blood vessel growth.

Bone (Osseous tissue)

calcified connective tissue that composes the skeleton

Bone matrix:

1. Osteoblasts

2. Osteocytes

3. Calcium salt deposits

4. Collagen fibers

Types of membranes

1. Cutaneous

2. Mucous

3. Serous

4. Synovial

Cutaneous membrane

• the skin

• largest membrane in body

• stratified squamous epithelium epidermis on connective dermis

• protection

Mucous membrane

lines passages that open to external environment (ex. respiratory)

Layers of the mucous membrane

epithelium, lamina propria, muscularis mucosae

Serous membrane (serosa)

• lines some internal body cavities and covers organs

• simple squamous epithelium (mesothelium) resting on layer of areolar tissue

• produces transudate

Transudate

Serous fluid that comes from blood

Synovial membrane

• lines moving, articulating joint cavities

• protects ends of bones

• lack a true epithelium

Synoviocytes

cells lining the cavity that produce synovial fluid

Types of serous membranes

1. pleura

2. peritoneum

3. pericardium

Pleura

lines pleural cavity (parietal) and surface of lungs (visceral)

Peritoneum

lines peritoneal cavity (parietal) and surface of abdominal organs (visceral)

Pericardium

lines pericardial cavity (parietal) and surface of heart (visceral)

Excitability

Cell's ability to respond to stimuli by changing its membrane potential

Excitable tissues

nervous and muscular tissue that are the highest developed excitable tissue

Membrane potential

found excitation through charge differences across the membrane

Nerve cells

Change voltage allowing for rapid transmission

Muscle cells

Voltage change allows for contraction

Nervous tissue

• Specialized for communication by electrochemical signals

• consists of neurons and neuroglia

Neurons

nerve cells that detect stimuli and respond by transmitting coded info to other cells

Neuroglia

Glial cells that protect and assist neurons

Cell body of neurons

Houses the nucleus and other organelles; protein synthesis

Dendrites

short branched processes that receive signals and transmit messages to the cell body

Axon

nerve fiber that send outgoing signals to other cells

Muscular tissue

• Specialized to contract when stimulated to exert physical force on other organs, tissues, or fluids

• important source of body heat

Types of muscular tissue

1. Skeletal muscles

2. Cardiac muscle

3. Smooth muscle

Skeletal muscle

1. Made of long thin cells called muscle fibers

2. Most skeletal muscles attach to bone

3. Contains multiple nuclei adjacent to plasma membrane

4. Striated

5. Voluntary control

Cardiac muscle

1. Limited to the heart wall

2. Cardiomyocytes

3. Intercalated discs

4. Striated

5. Involuntary

Cardiomyocytes

short branched endings with one centrally located nucleus

Intercalated discs

at ends of cell and join neighboring cardiomyocytes

Gap junctions

allow flow of small molecules

Smooth muscle

1. Made of short, fusiform shaped cells that undergo MITOSIS

2. Cells have a central nucleus

3. Most is visceral muscle in the wall of hollow organs

4. No striations

5. Involuntary