(Lesson 3) Chapter 4-Tissues Flashcards
Tissue
A group of cells of similar structure that perform a common function. Between cells are nonliving materials called extra cellular matrix
Epithelium
A sheet of cells that covers a body surface or lines a body cavity. Almost all outer and inner surfaces of the body are lined with it.
Special Characteristics of Epithelia Cellularity
Cellularity-made of almost entirely cells, very little extracellular matrix.
Special Characteristics of Epithelia Specialized Contacts
Adjacent epithelial cells are directly joined at many points by special cell junctions.
Special Characteristics of Epithelia Polarity
cells near apical surface differ from cells at the basal surface.
Special Characteristics of Epithelia Support by connective tissue
All epithelial sheets are supported by layer of connective tissue.
Special Characteristics of Epithelia Avascular but innervated
Most tissues are vascular (contain blood vessels), but epithelia is avascular (lacks blood vessels). Epithelia receives nutrients from capillaries in the underlying connective tissue. Although blood vessels do not penetrate epithelial sheets, nerve endings do. Epithelia is innervated
Special Characteristics of Epithelia Regeneration
Epithelia has high regenerative capacity. Cells are destroyed through various means but as long as they are receiving adequate nutrition they can be replaced quickly by cell division.
Classification of Epithelia
Simple (one layer) or Stratified (multiple layers). Then by shape: Squamos (Platelike, flat), Cuboidal (like cubes), or columnar (taller than they are wide). The shape of the nucleus conforms to that of the cell so identifying the nucleus can help determine what type it is. Squamos nuclei are disks, cuboidal are spherical, and columnar are elongated ovals.
Simple Squamos Epithelium
Single layer of flat cells. Used for diffusion or filtration. Walls of capillaries are exclusively this type. Thinness encourages exchange of nutrients and waste. Also form thin walls of the air sacs where gas exchange occurs
Simple Cuboidal Epithelium
Single layer of cubed shaped cells. Forms walls of ducts of glands and tubules in the kidney. Also for diffusion or filtration.
Simple Columnar Epithelium
Single layer of tall cells aligned like soldiers in a row. Lines the digestive tube from stomach to anal canal. Functions in the active movement of molecules-absorption, secretion, and ion transport. Thin enough to allow large numbers of molecules to pass through it quickly and thick enough to house cells needed to perform complex processes.
Cilia
whiplike bristles on the apex of some epithelial cells that beat rhythmically to move substances across certain body surfaces. Simple Ciliated columnar epithelia is found inside uterine tube to help move ovum to uterus.
Pseudostratified Columnar Epithelium
Varied in height. All cells rest on basilar membrane but only tall cells reach the apical surface. Nuclei lie at different levels, giving the false impression that epithelium is stratified. Functions in secretion and absorption. A ciliated type lines the respiratory tubes to propel sheets of dust-trapping mucus out of the lungs.
Stratified Squamos Epithelia
Many squamos cell layers. In the deeper layers the cells are cuboidal or columnar. This cell type is the thickest and best adapted for protection. Forms epidermis, inner lining of mouth, esophagus, and vagina. Forms outermost layer of skin and extends a certain distance into every body opening directly continuous with the skin.
Keratin
Tough protective protein.
Keratinized
Surface cells of epidermis contain keratin.
Stratified Cuboidal/Columnar Epithelia
Rare types of tissue, located in the ducts of sweat, mammary, and salivary glands.
Transitional Epithelia
Lines the inside of the hollow urinary organs. Transitions in shape from 6 layers to 3 as organs stretch.
Glands
Organs that secrete a product.
Secretion
The process whereby gland cells obtain needed substances from the blood and transform them chemically into a product that is discharged from the cell.
Exocrine Glands
External Secretion
Endocrine Glands
Internal Secretion. Lack ducts. Secrete directly in to the tissue fluid that surrounds them. These glands produce messenger molecules call hormones (Exciters). Hormones then enter capillaries and travel through bloodstream to specific target organs far removed from the glands that produced the hormone.
Basal Lamina/Basement membrane
Consists of proteins secreted by the epithelial cells. Acts as a selective filter, determining which molecules from the connective tissue can enter epithelia.
Connective Tissue
The most diverse and abundant type of tissue. 4 Main types: Connective Tissue Proper, Cartilage, Bone Tissue, and Blood.
Connective Tissue Functions
- Supports and binds other tissues. 2. Holds body fluids. 3. Defending the body against infection 4. Stores nutrients as fat
Mesenchyme (Connective Tissue Type)
Found abundantly in embryos. All connective tissue originates from this.
Areolar (Connective Tissue Type)
Cushions. A connective tissue in which fibers are loosely arranged in a net or meshwork.
Dense (Connective Tissue Type)
Fibrous connective tissue. Contains more collagen than areolar, which are arranged for strength-tendon or ligament. Can resist extremely strong pulling forces.
Adipose (Connective Tissue Type)
Similar to Areolar in structure and function, but stores more nutrients. Fat cells (lipids) account for 90% of mass. Used for storage and insulation.
Cartilage (Connective Tissue Type)
Rubbery, gristle, resists compressive forces.
Collagen
a major protein, is the matrix molecule that gives rise to bundles of strong fibers. The nonliving component of connective tissue is called “extracellular matrix.
Bone (Connective Tissue Type)
Osteocytes are surrounded by a calcified extracellular matrix. Supports and protects body structures.
Blood (Connective Tissue Type)
The fluid inside blood vessels. Does not bind, support. Is connective tissue because it develops from mesenchyme cells. Blood cells are surrounded by nonliving matrix-liquid blood plasma-which is the transportation vehicle for cardiovascular system.
Muscle Tissue
Muscle tissue is responsible for most movement in the body. It functions by contraction, is primarily controlled by the nervous system, and performs in both voluntary and involuntary movement. Muscle tissue is highly cellular and well vascularized.
Muscle Types
Muscle Tissue, Skeletal Muscle Tissue, and Cardiac muscle tissue.
Nervous Tissue
comprises the organs of the nervous system (brain, spinal cord, and nerves). It is composed of neurons, the functional unit of the tissue, and supporting cells which provide nourishment, protection, and insulation. Nervous tissue conducts electrical impulses and delivers them throughout the body.
Skin
The largest organ in the body.
Epidermis
keratinized stratified squamous epithelium that contains 4 types of cells: keratinocytes, melanocytes, Merkel Cells, and Langerhans cells
Keratinocytes
the most abundant epidermal cells. Produce Keratin.
Keratin
a tough fibrous protein that gives the epidermis its protective properties. Also produce antibiotics and enzymes that detoxify harmful chemicals to which the skin is exposed.
Hypodermis
The hypodermis is the deep layer of skin and is comprised of adipose and areolar connective tissues. It serves to anchor the skin to underlying muscle. It allows the skin to slide freely.
Skin functions
protection (chemical, physical, and biological barriers) temperature regulation cutaneous (skin) sensation metabolic functions blood reservoir excretion
Thick skin
Found on palms of hands and soles of feet. Consists of five layers (strata).
Thin skin
Found everywhere else, only consists of four layers (strata).
Layers of epidermis
From external to internal, are corneum (horny), lucidum (clear-not in thin skin), granulosum (granular), spinosum Spiny), and basale (base). Can Lazy Gary Swim Backwards.
Merkel Cells
Found in stratum basale. Each cell is associated with a sensory nerve ending.
Melanocytes
10-25% of cells in the stratum basale. Spider shaped. Make dark skin pigment called melanin. provides dark skin pigment (color) and offers protection from UV radiation; its levels increase in response to sunlight.
Langerhans cells
Part of the immune system. Shaped like stars. They take up foreign proteins that have invaded the epidermis.
Dermis
It is strong yet flexible. Dense connective tissue with an abundance of collagen comprises this layer. It is your “hide,” and when you “tan” it (in the case of animals) you have leather! It is both vascularized and innervated, meaning that it bleeds and hurts when you damage it.
Carotene
a pigment obtained by eating plants, can accumulate in the epidermis, giving an orange hue to the skin
Hemoglobin
within the blood gives skin a reddish hue. In the absence of oxygen, e.g., a drowned person, the blood loses its reddish color (the victim appears bluish).
Nails
scalelike modification of the epidermis. Like hair, nails contain hard keratin. They grow from the lunula (nail matrix).
Sudoriferous Glands
Sweat glands. 2.5 million glands function as evaporative coolers producing up to 12 liters of sweat per day.
Eccrine glands
More numerous than apocrine. Produce true sweat. Most abundant on palms, soles and forehead. Run through pores.
Apocrine glands
Mostly confined to the axillary, anal, and genital areas. Sweat consists of fatty substances and proteins, along with true sweat. Run through hair follicles. odorless until decomposes and then takes on a musky smell (body odor)
Sebaceous Glands
Skin’s oil glands. On the whole external surface of the body minus palms and soles. They produce sebum. Most are associated with hair follicles.
Holocrine Secretion
The way sebum is secreted. Central cells in the alveoli accumulate oily lipids until they become engorged and burst apart. Whole cells burst to form the product.
Sebum
Collects dirt, lubricates hair and skin, slows water loss, and helps kill bacteria
Acne
When so much sebum is produced that it cannot be ducted from the glands quickly enough. The sebaceous gland is blocked by sebum and is likely to become infected by bacteria, inducing inflammation.
Vitiligo
An abnormality of skin pigmentation characterized by light spots surrounded by areas or normally pigmented skin. Can be cosmetically disfiguring, especially in dark-skinned people. Melanin is missing; this pigment is also found in the retina, normally hiding the capillaries.
Melanoma
Cancer of the melanocytes, or the melanin-producing cells of the stratum basale. Most dangerous of skin cancers.
Other skin cancers
Basale Cell Carcinoma, Squamos Cell Carcinoma
