ephe midterm 1

Cells: Basic building blocks of all living things

• Membrane

  • Lipid bilayer surrounding cell/organelle

• Genetic Material

  • e.g., DNA

• Cytosolic fluid

Tissues: Similar cells functioning together

• 4 types of tissues in the body (CMEN): Connective Tissue, Muscle Tissue, Epithelial Tissue, Nervous Tissue

Organ: 2 or more tissues that perform a specialized function

System: Group of organs functioning cooperatively

*Rough ER = Attached Ribosomes, Smooth ER = Detached Ribosomes

EPITHELIAL TISSUE

Epithelial cells = “covering” cell

Epitelial Tissue

• Sheets of EC that cover all body surfaces,, lines all body cavities and organs, and forms most glands.

• ET is almost always found close to CT (Connective Tissue)

• ET is classified based on the type of layering

  • Simple (one layer)

  • Stratified (multiple layers)

• …and based on the shape of the cells

EPITHELIAL TISSUE	SHAPE	SPECIFIC LOCATION	GENERAL FUNCTION
Simple Squamous		Mesothelial cells; lining of ventral ventral body cavities, heart and blood vessels, alveoli (lungs), *lots of permeability	Reduce friction, control blood vessel permeability. Perform absorption and secretion.
Simple Cuboidal		Glands, ducts, portions of kidney tubules, thyroid gland	Limited protection, Absorption and Secretion
Simple Columnar		Lining of the stomach intestine, gall bladder, uterine tubes, and collecting ducts of kidneys	Protection, Absorption and Secretion
Stratified Squamous		Surface of the skin, lining of the mouth, throat, esophagus, rectum, anus, and vagina	Provides physical protection against abrasion, pathogens and chemical attacks
Transitional		Urinary bladder, renal pelvis, ureters	Permits expansion and recoil after stretching
Pseudostratified Ciliated Columnar		Lining of the nasal cavity, trachea and bronchi, portions of the male reproductive tract	Protection and secretion

GENERAL FUNCTIONS OF EPITHELIAL TISSUE

• PROTECTION

  • e.g., Stratified squamous cells

• SECRETION

• ABSORPTION

• EXCRETION/FILTRATION

• DIFFUSION

  • e.g., Simple squamous cells

• SENSATION

• TRANSPORT

Consider the Following: Why are some cells..?

CHARACTERISTICS OF EPITHELIAL TISSUE

• Cellularity: highly packed cells

• Polarity: apical (top) and basal (bottom) surfaces

• Attachment: Hemidesmosomes attach epithelial cells to protein fibers in basement membrane.

• Avascular: without blood cells (EC must obtain nutrients through diffusion and absorption.

• Regenerative: cells proliferate (multiply) quickly

ET is always set up with little space and very organized.

EPITHELIAL CANCERS

• 85% of cancers are cancers of the ET origin and are called carcinomas

• EC are highly regenerative and therefore have greater chance of error

GLANDULAR TISSUE

• organized collection of secretory EC

Types of Glandular Epithelium

*Epithelial ducts may release secretions unaltered or they may alter it through reabsorption, secretion, or counter transport.

CLASSIFICATION OF GLANDULAR EPITHELIUM

TYPES OF GLAND SECRETIONS:

• Serous gland: produces watery solutions mixed with enzymes.

• Mucous gland: Secrete glycoproteins called mucins.

• Mixed endocrine gland: Mixture of cells that secrete both serous and mucous secretions (e.g., pancreas secreting both insulin and glucagon.

METHOD OF SECRETION

Merocrine (eccrine): Product secreted by exocytosis onto the surface of the cell. e.g., release of saliva from serous glands Apocrine: Product secreted by shedding of the apical portion of the cell’s cytoplasm (“pinching off the membrane”). e.g., Lactiferous cells of the mammary glands. Holocrine: Cell bursts. During holocrine secretion, the entire cell becomes packed with secretory products and then bursts apart. Secretion is released and then cell dies. e.g., Sebaceous glands.

INTRO TO CONNECTIVE TISSUE

Learning Outcomes:
1. Describe the general functions of connective tissue (CT) and the structural elements found in all CT.
2. Recall the subtypes of CT and classification system.
3. Recognize structural elements common to all CT.

CT Proper
1. Recognize unique characteristics of each subtype of CT Proper including the relative proportion of
cells/proteins/ground substance.
2. Differentiate between fixed and wandering cells found in CT proper and describe functions of those discussed in lecture.
3. Recall and associate each subtype of CT proper with its respective functions and locations.
4. Using the integumentary system as an example, specify the type of epithelial tissue and connective tissue found in the epidermis, layers of the dermis, sebaceous glands, and sweat glands.

Membranes/Fascia
1. Compare and contrast the characteristics and locations of mucous, serous, cutaneous and synovial membranes.
2. Differentiate between superficial fascia, deep fascia, and subserous fascia in terms of location and structure.

Mind Map: Connective Tissue Proper

Central Idea: Connective Tissue Proper

• Connective tissue proper is one of the four main types of connective tissue in the body.

• It is responsible for providing structural support, connecting and protecting organs and tissues.

• CT General Funegctions:

  • Provides structural framework for organs

  • Protects internal structure

  • Connects tissue types

  • Transports fluid and solutes

  • Stores energy

  • Assists the immune system.

EXAMPLES OF CELLS FOUND IN CT PROPER

• Fibrocytes: Supports and maintains CT Proper

• Fibroblasts: Makes and remodels CT Proper

  • Produces all connective tissue fibers.

  • Each fibroblast manufactures

• Adipocytes: stores energy

  • Contains a single lipid droplet that occupies almost the entire cell.

• Immune cells

  • Leukocytes: Various white blood cells

  • Mast Cells: Stimulate inf. response

  • Macrophages (clean up cells): phagocytize (process in which a cell uses it’s plasma membrane to engulf a large particle) pathogens and damaged cells

    • There are fixed and wandering macrophages

    • Fixed Macrophages: large, amoeboid cells scattered among the connective tissue fibers. They engulf damaged cells, dead cells, and pathogens that enter the tissue.

    • They release chemicals that attract wandering cells in the body’s defense mechanisms.

    • Wandering (Free) Macrophages: relatively large phagocytic cells that wander rapidly through the connective tissues of the body.

    • Termed “Monocytes” when circulating within the blood.

    • Act as a front-line defense that is reinforced by the arrival of free macrophages and other specialized cells.

Loose Connective Tissue	CHARACTERISTICS	IMAGES
Areolar Connective Tissue cushions organs. provides support yet also independent movement. immune cells provide defense. delivers nutrients and removes waste.	Found beneath the skin and between organs Contains fibroblasts, collagen, and elastic fibers Provides support and flexibility
Adipose Tissue protects absorbs shock insulates ~80% of adipose tissue is adipocytes	Stores energy in the form of fat Insulates and cushions organs Found beneath the skin and around organs
Reticular Connective Tissue predominating in reticular fibers light and strong; supporting framework of some organs oriented in multidirectional pattern	Forms the framework of organs like the liver and spleen Contains reticular fibers and cells Provides support and filtration

Dense Connective Tissue	CHARACTERISTICS	IMAGES
Dense Regular Connective Tissue stabilize and support surrounding tissues and organs located: aponeuroses, respiratory tract, blood vessels, tendons, ligaments	Found in tendons and ligaments Contains densely packed collagen fibers Provides strength and resistance to tension
Dense Irregular Connective Tissue high portions of collagenous fibers provides strength makes skin resistant to tearing by stretching located: digestive tract, lymph nodes, fascia	Found in the dermis of the skin and joint capsules Contains collagen fibers arranged in different directions Provides strength and support in multiple directions
Elastic Connective Tissue provide strength and resistance to stretching elastic fibers some collagen located: walls of large, elastic arteries	Found in the walls of large arteries and vocal cords Contains elastic fibers Provides elasticity and recoil ability

Get to Know the Following

1. Connective tissues are found throughout the body. They are never exposed to the environment outside the body.

2. All CT have 3 basic components: (1) Specialized Cells, (2) Extracellular Protein Fibers, (3) A fluid known as Ground Substance.

3. The extracellular protein fibers and ground substance form the matrix that surrounds the cells.

4. CT consists almost entirely of extracellular matrix (ECM).

Specialized CT Cells: includes a variety of distinct tissues with specialized cells and unique ground substances that result in wide-ranging properties

• adipose

• cartilage

• bone

• blood

• lymphatic

Extracellular Protein Fibers: The extracellular matrix (ECM) is the non-cellular component present within all tissues and organs, and provides not only essential physical scaffolding for the cellular constituents but also initiates crucial biochemical and biomechanical cues that are required for tissue morphogenesis, differentiation and homeostasis

• collagen

  • STRENGTH

  • long, straight, unbranched.

• reticulin

  • STRENGTH

  • fine collagen fibrils that are shorter, thinner, and lighter (but still strong).

• elastic fibers

  • STRETCH

  • branching and wavy = stretch and recoil.

Ground Substance: Gelatinous substrate that lies between cells and fibers of the CT.

• cartilage

• umbilical cord

• secreted by fibroblasts

• contains a high concentration of glycosaminoglycans (i.e., hyaluronic acid)

  Membranes; Fascia

Epithelial Membranes: Epithelial sheet with an underlying CT layer. Forms an internal framework in body.

4 TYPES OF EPITHELIAL MEMBRANES	CHARACTERISTICS	IMAGES
Mucous Membranes: moist line passageways that open to the exterior of the body e.g., simple columnar epithelium of the digestive tract, stratified squamous epithelium of the oral cavity, epithelium in urinary tract.	forms a barrier that resists entry of pathogens. areolar tissue component of mucous membrane is called lamina propria. LP forms a bridge between epithelium to underlying structures.
Serous Membranes: line body cavities that lack openings to the exterior minimize friction between parietal and visceral surfaces e.g., the pleura (lines pleural cavities and covers lungs), the peritoneum (lines the peritoneal cavity and covers the surfaces of the enclosed organs), the pericardium (lines the pericardial cavity and covers the heart	consists of mesothelium and supported by a thin layer of areolar connective tissue very thin and attach to the body wall and organs they cover fluid formed on the surface of serous membrane s called a transudate examples of transudates are the pleural fluid, peritoneal fluid, and pericardial fluid
Cutaneous Membrane (skin): covers the body surface first line of defense against environmental pathogens	keratinized stratified squamous epithelium and an underlying layer of areolar connective tissue thick, relatively waterproof, and usually dry
Synovial Membranes: line and lubricate joint cavities movement joints are surrounded by a fibrous capsule and contain a joint cavity lined by a synovial membrane.	no basement membrane cellular layer is incomplete, with gaps between adjacent cells its “epithelial cells” derive from macrophages and fibroblasts of the adjacent connective tissue

Fascia

Cartilage

Type of Supporting Connective Tissue (cartilage, bone)

• Tough, but flexible, CT that provides support

• Key cells: chondrocytes

  • secrete collagen fibers and chondroitin sulfate (forms matrix)

  • found in lacunae

• Predominant protein fibers: collagen

• Matrix: firm gel; does not allow for easy diffusion of nutrients, gases

• Avascular

Perichondrium:

• Separates cartilage from other tissues

• Composed of 2 layers:

• Perichondrium is vascular!

1. Fibrous layer: dense irreg. CT

2. Cellular layer: chondroblasts

Bone

Type of Supporting CT: Osseous Tissue, Strong and dynamic CT that provides support

• Key cells: osteoprogenitor cells, osteoblasts, osteocytes, osteoclasts,

• Predominant protein fiber: collagen

• Matrix: calcium salts (e.g., calcium phosphate)

• Vascular!

Bone Matrix:

• 60-70% bone minerals including insoluble crystals of
  calcium phosphate (e.g., hydroxyapatite)

• ~30-40% collagen

  • Functions: calcium phosphate interacts with calcium hydroxide to make the crystals. As the crystals form they incorporate other calcium salts and ions. The inorganic components enable bone to resist compression (hard and strong)

  • Collagen is tough but flexible. In bone, collagenous fibers and non-collagenous proteins provide framework for the formation of mineral crystals.

• Info I stole from this youtube video:

  • Bones are composed primarily of an extracellular calcified material called the bone matrix or collagen matrix.

  • Three main types of cells in bones: osteocytes, osteoblasts, and osteoclasts.

  • Osteocytes are found in cavities or lacunae between the layers of the bone matrix and assist with bone nutrition.

  • Osteoblasts are found along the surface of bones and within the bone matrix, responsible for synthesizing and mediating mineralization of the bone matrix.

  • Osteoclasts are large multinucleated cells responsible for removing calcified bone matrix, allowing for bone turnover and remodeling.

  • Bones have two main types: compact or cortical bone and cancellous or trabecular bone.

  • Lamellar bone is arranged in sheets, while woven bone has randomly arranged collagen fibers.

Bone Histology

Functions of the parts of the bone

Periosteum: (NOTE: no periosteum within synovial joints)

• covers bone surfaces & has a fibrous layer

• that is superficial & cellular layer that is deep

Endosteum:

• membrane lining the inner surface of the compact bone

Osteogenesis:

• Fetal development (<8 weeks) begins as hyaline cartilage. After

  ~8 weeks the bony skeleton starts to to form.

• Ossification – process of bone formation that completes early in

  adulthood:

  a. Intramembranous ossification: bone formed from undifferentiated

  sheets of CT

  b. Endochondral ossification: bone replaces a hyaline cartilage model

Intramembranous Ossification - bone formed from undifferentiated sheets of CT

• Forms directly from sheets of mesenchymal connective tissue (i.e., undifferentiated tissue)

• Process starts during fetal development at ~8 weeks in utero.

• Specific to the clavicle, mandible, skull, and bones of the face

• Ossification is mostly complete after birth with facial bones

• ossifying at end of adolescent growth spurt.

Endochondral Ossification (bone replaces hyaline cartilage model)

• Begins ~8-12 weeks in utero.

• Chondroblasts form hyaline cartilage model - this serves as a template that will be replaced by new bone.

• Specific to the bones of the limbs, vertebrae, and hips

• Bones grow in length via endochondral ossification and grow in diameter by appositional growth

Endochondral Ossification - 2 main steps

1. Initiation

2. Increasing length

Growth Plates

• made of hyaline cartilage

  • Hyaline cartilage is a flexible and smooth type of cartilage.

  • Hyaline cartilage provides a cushioning effect, reducing friction between bones.

  • Injuries to growth plates can lead to growth disturbances or deformities.

  • Hyaline cartilage lacks blood vessels, nerves, and lymphatics.

Appositional Growth: Increasing Diameter of Bone

• Bone enlarges in diameter just deep to periosteum

• Occurs concomitant with longitudinal growth AND continues after growth cease

• As new bone added to outer surface by osteoblasts, osteoclasts resorb bone on inside enlarging medullary cavity

Factors Regulating Bone Growth

Diet: Calcium, phosphate salts, Vitamin A, C, D

Hormones: calcitriol, parathyroid hormone, calcitonin, growth hormone, thyroxine, sex hormones.

Weight bearing physical activity: particularly high-impact loading and resistance training!