Chapt. 5: Tissue Organization

Which of the following is a correct statement about a simple epithelium?

All of the cells are in direct contact with the basement membrane.

What characteristics are common to all connective tissues?

Connective tissues come in a vast variety of forms, yet they typically have in common three characteristic components: cells, large amounts of amorphous ground substance, and protein fibers. Together the ground substance and fibers make up the extracellular matrix.

What are some characteristics of all types of epithelium?

Contiguous cells Polarity (apical, lateral and basal cell surfaces) Intercellular junctions Basement membrane (extracellular matrix) Supported by connective tissue (lamina propria) Avascular, innervated. Squamous, cuboidal, columnar. Despite there being many different types of epithelialtissue all epithelial tissue have just five characteristics, these are cellularity, polarity, attachment, vascularity, and regeneration. Cellularity as the name suggests means that the epithelium is made up almost entirely of cells.

In what regions of the body would you expect to find hyaline cartilage, fibrocartilage, and elastic cartilage, and why would these types be located in these regions?

Hyaline cartilage- trachea; it provides structural support. Fibrocartilage- intevertebral discs; acts as a shock absorber. Elastic cartilage- ears; maintains shape while permitting extensive flexibility. Hyaline cartilage: Fetal skeleton, articular ends of long bones, larynx, trachea, nose. Found here because it provides a smooth surface for joint movement, it is a model for bone growth, and it supports soft tissue. Fibrocartilage: Intervertebral discs, pubic symphysis, menisci of knee. Found here because it resists compression and absorbs shock well. Elastic cartilage: External ear, epiglottis of the larynx. Found here because it is particularly flexible while maintaining its structure. These areas receive more multi-directional pressure.

__________ membranes line body cavities that typically open to the exterior, such as the nasal cavity.

Mucous

Name the four types of body membranes, and cite a location of each type.

Mucous: Lines the digestive, respiratory, reproductive, and urinary tracts.Serous: Lining the friction locations between body cavities and organs and between various organs themselves.Cutaneous: Covering the body as skin. Synovial: Lining some joints. 1. synovial- joints 2. cutaneous- skin that covers the body's surface 3. mucous- in the nose 4. serous- part of the pericardium. Membranes are thin layers of epithelial tissue usually bound to an underlying layer of connective tissue. Membranes cover, protect, or separate other structures or tissues in the body. The four types of membranes are: 1) cutaneous membranes; 2) serous membranes; 3) mucous membranes; and 4) synovial membranes. The cutaneous membrane is skin. Skin consists of a layer of stratified squamous epithelium (epidermis) firmly attached to a thick layer of dense connective tissue (dermis). It differs from other membranes because it is exposed to air and is dry. The serous membranes (or serosae) consist of simple squamous epithelium (a mesothelium) supported by a layer of connective tissue (areolar). These moist membranes line the closed, internal divisions of the ventral body cavity. The three types of serous membranes are: 1) the pleura, lining the pleural cavities and covering the lungs; 2) the peritoneum, lining the peritoneal cavity and covering the abdominal organs; and 3) the pericardium, lining the pericardial cavity and covering the heart. The mucous membranes (or mucosae) consist of epithelial tissue (usually stratified squamous or simple columnar epithelia) on a layer of loose connective tissue called the lamina propria (from the Latin, meaning "one's own layer"). The mucosae line the body cavities that open to the exterior, such as the digestive, respiratory, reproductive, and urinary tracts. These membranes are kept moist by bodily secretions. Synovial membranes are composed of connective tissue. They surround the cavity of joints, filling the space with the synovial fluid that they make. The synovial fluid lubricates the ends of the bones allowing them to move freely.

What is the difference between neurons and glial cells in nervous tissue?

Neurons receive, transmit, and process nerve impulses, but Glial cells don't transmit nerve impulses, instead they are responsible for protection, nourishment, and supporting neurons. Neurons are the conducting cells of the nervous system. A typical neuron consists of a cell body, containing the nucleus and the surrounding cytoplasm; several short radiating processes (called dendrites); and one long process (called the axon), which terminates in twiglike branches and may have branches projecting along its course. Glial (Neuroglial) cells do not conduct nerve impulses, but, instead, support, nourish, and protect the neurons. Glial cells are far more numerous than neurons and, unlike neurons, are capable of mitosis. The neuron can be divided into sensory, motor and interneurons (as well as unipolar, multipolar etc). By contrast, glial cells is an umbrella term for a variety of support cells: Astrocytes, Microglia, Oligodendroglia, Satellite cells, and Schwann cells, all of which are key to the neural support system (outlined below). The number and divisions of the various kinds of neurons and glial cells differ, making them unrelated. This links onto the function of each type of cell. The neuron, being incredibly specialized, at a cellular level has primarily one overarching function: to fire. By this, I mean that the neuron has the potential to transmit electrical impulses across a synapse to the next, ultimately resulting in higher order functions such as movement and thought. Their functions can therefore broadly be divided into two areas: receiving and transmitting information. Conversely, each type of glial cell has its own specific functions that differ from neurons, such as the formation of myelin (the protective fatty sheath facilitating rapid electrical signalling), guiding migration of neurons during neural development, regulating neurotransmitter release, axonal guidance and formation, and even inflammatory and immune responses. Evidently, the roles of neurons and glial cells differ greatly. The clear differences among the two are the inevitable lack of the long protruding axon in most glial cells (except for perhaps the oligodendryte). Furthermore, neurons have two protrusions on each end, referred to as dendrites and axons, while glial cells only have a singly labelled outgrowth. Moreover, glial cells are unable to transmit signals or messages across each other via action potentials, and hence only have a resting potential - whereas neurons have the capacity to generate action potentials as well. Glial cells also lack the capability to release neurotransmitters as opposed to neurons; However, this is being contested with recent research displaying possible neurotransmission by astrocytes. Hence up until now, glial cells have known to be more as the bystanding support system of cells, but it is still an ongoing topic of research. I have also read sites stating that the glial cells 'clean up' and 'provide nutrients' to neurons, but have not been able to find much research indicating how this occurs, except by perhaps activating pro-inflammatory cytokines that support cell apoptosis during neuronal damage.

What are the similarities and differences between skeletal muscle, cardiac muscle, and smooth muscle?

Smooth muscle: involuntary, non-striated, single nucleus. Cardiac muscle: involuntary, striated, single or double nuclei. Skeletal muscle: voluntary, striated, multi-nucleated, with nuclei at the periphery. Skeletal and Cardiac muscles are strained, smooth muscle is non-strained. Cardiac and Smooth muscles are involuntary, and skeletal muscles are voluntary.

What are the main structural differences between dense regular and dense irregular connective tissue?

The primary difference between dense regular and dense irregular connective tissueis that dense irregular connective tissue has a multidimensional fiber orientation (Fig. 2-2). This multidimensional orientation allows the tissue to attenuate forces in numerous directions. Dense regular tissue is densely packed with parallel collagen fibers and very little ground substance. Dense irregular tissue collagen fibers are randomly arranged and it has more ground substance than dense regular. Dense regular tissue attaches muscles to bones or to muscles, attaches bones to bones, and withstands great tensile strength. The bundles of collagen fibers in dense irregular connective tissue are much thicker and they are arranged irregularly.

List the epithelium types that line (a) the lumen of the stomach, (b) the oral cavity, (c) the urinary bladder, and (d) the air sacs (alveoli) of the lungs.

a) simple columnar b) stratified squamous c) transitional d) simple squamous

Which tissue contains a calcified ground substance and is specialized for structural support?

bone connective tissue

Which connective tissue type is composed of cells called chondrocytes?

cartilage

Which of the following is not a characteristic of areolar connective tissue?

densely packed protein fibers

All of the following are characteristics of an epithelium except

it contains abundant blood vessels

A gland that releases its secretion by exocytosis out of secretory vesicles is called a(n) __________ gland.

merocrine

What are the types of exocrine glands, classified by method of secretion, and how does each method of secretion work?

merocrine gland- secrete oil by means of exocytosisapocrine gland- secretes pheromones by pinching off the apical surface of the cellholocrine gland- secretes products through the destruction of the entire secretory cell, for example, the sebaceous glands. Merocrines glands (e.g., salivary glands) secrete their product from intact cells. Apocrine glands (e.g., mammary glands) accumulate their secretory product at the apical surface of each cell, which then separates from the remainder to from a secretion in the lumen of the gland. The cells then repair themselves. Holocrine glands (e.g., sebaceous or oil glands) are those in which entire cells and their secretions accumulate as the gland's secretory product. Discharged cells are replaced by new ones.

Which epithelial tissue type lines the trachea (air tube)?

pseudostratified ciliated columnar epithelium

Describe the two main criteria by which epithelia are classified.

simple, meaning one layer of cells for filtration absorption and secretion, and stratified, meaning more than one layer of cells mainly for protection against abrasion. The different types of epithelial tissues are characterized by their cellular shapes and arrangements: squamous, cuboidal, or columnar epithelia. Single cell layers form simple epithelia, whereas stacked cells form stratified epithelia.

Which muscle type consists of long, cylindrical, striated fibers with multiple nuclei located at the periphery of the fiber?

skeletal muscle

Which tissue type is formed from mesoderm?

smooth muscle tissue