Flashcards in Exam 1 Part two Deck (109):
What is meant by passive transport of materials into a cell?
Substances move across a plasma membrane without the expenditure of energy by the cell. Materials move along a concentration gradient (from high to low). No cellular energy (ATP) is needed for it to occur
What are the passive processes
Simple diffusion, osmosis, facilitated diffusion, & bulk filtration
Simple diffusion is
Occurs when substances move across membranes unaided because they are small or non polar. Higher to lower. Continues until evenly distributed
Water diffuses from one side of the selectively permeable membrane to the other. In the body the movement of water between the blood & the extracellular fluid around cells occurs by osmosis
Facilitated diffusion is
Requires the participation of specific transport proteins that help the specific substances move across the plasma membrane. Glucose & amino acids move across the membrane by this means. Transport is aided by a protein.
Bulk filtration is
Involves the diffusion of solvents & solutes together across the selectively permeable membrane. An example is when fluid & certain solutes are transported from the blood into the extracellular fluid.
Make up most of the plasma membrane lipids. They contain both water-soluble & water-insoluble regions. They are called polar meaning they have a charge distributed unevenly through the molecule making one region a positive charge and one region a negative charge. The polar "head" is charged and hydrophilic. The two tails are uncharged and hydrophobic.
What is the fluid mosaic
Proteins and substances such as cholesterol become embedded in the bilayer, giving the membrane the look of a mosaic. Because the plasma membrane has the consistency of vegetable oil at body temperature, the proteins and other substances are able to move across it. That’s why the plasma membrane is described using the fluid-mosaic model.
What is selectively permeable?
The plasma membrane, it regulates the passage of gases, nutrients, & wastes between the internal & external environments. It is essential to a cells existence because it allows the entrance or exit of substances to be regulated or restricted
Adenosine triphosphate. It provides the energy for that transport. Releases energy when the bond that attaches its third phosphate to the rest of the molecule is broken
What are the functions of the cell membrane?
Contains receptors for communication; forms intercellular connections; acts as physical barrier to enclose cell contents; regulates material movement into and out of the cell.
What are the various ways that molecules move through the cell membrane?
*Passive transport: Simple diffusion, osmosis, facilitated diffusion, & bulk filtration
*Active transport: Ion pumps & bulk transport
Active transport is
The movement of a substance across a plasma membrane against a concentration gradient. Materials go from low to high. Requires cellular energy (ATP) & sometimes a transport protein
Ion pumps are
Active transport processes that move ions across the membrane are called ion pumps. One type of ion pump is the sodium potassium pump. It moves one ion into the cell while simultaneously removing another type of ion from the cell.
Bulk transportation is
Macromolecules, such as large proteins and polysaccharides, move across the membrane via the active transport processes called exocytosis & endocytosis
Large molecules are secreted from the cell & normally packaged within intracellular transport vesicles which move toward the plasma membrane
When extracellular macromolecules & large particulate matter are packaged in a vesicle that forms at the cell surface for internalization into the cell.
Complex, organized structures with unique, characteristic shapes. Each type of organelle performs a different function for the cell. They assume specific roles in growth, repair, and cellular maintenance. Two types of organelles are membrane bound organelles and non membrane bound organelles
Membrane bound organelles
1) Endoplasmic reticulum
2) Golgi apparatus
Non membrane bound organelles
4) Centrosome & centrioles
5) Cilia & flagella
Thin, microscopic projections extending from the surface of the plasma membrane. Not all cells have microvilli. They normally occur in the small intestine.
Projections extending from the cell. Composed of cytoplasm & supportive microtubules, they are enclosed by the plasma membrane. Usually found in large numbers on the exposed surfaces of certain cells.
Function of cilia
Move fluid, mucus, & materials over the cell surface
Function of microvilli
Increase membrane surface area for increased absorption &/or secretion
When a cell is not dividing, the DNA & it's associated proteins are in the form of an unwound, finely filamented mass called chromatin. Site of genes in the DNA.
Membrane-enclosed sacs; contain large amounts of enzymes to break down harmful substances. Convert hydrogen peroxide formed during metabolism to water.
A duplicated chromosome consists of two genetically identical structures called sister chromatids. Each one is composed of an identical DNA double helix and the two sister chromatids are joined together by proteins at a contracted region called the centromere
The region where the two sister chromatids are joined together by proteins
What is interphase? What role does it serve in the cell cycle?
Normal metabolic activities with no change in cytoplasm or nucleus. Cell is NOT dividing and chromosomes are NOT visible. This is the time when DNA is replicated.
Collagen fibers are
Composed of the protein collagen. They are strong, flexible, & resistant to stretching. Most abundant protein in the body.
Elastic fibers are
Contain the protein elastin and are thinner than collagen fibers. They stretch easily, branch, rejoin, and appear wavy.
Reticular fibers are
Thinner than collagen fibers. They contain same protein subunits that collagen has, but are combined in a different way. Tough but flexible. Abundant in the stroma. They support organs & resist external forces.
Neuron v. neuroglia
Neurons: Responsible for control; info processing, storage, & retrieval; internal communication
Neuroglial cells: Support & protect neurons
This type of tissue doesn't have any striations
An example of merocrine secretion
Ground substance is
Part of extracellular matrix
Goblet cells is
Unicellular exocrine gland
Dense regular connective tissue are
Parallel arrangement of protein fibers
Blood vessel lumen
Contains intercalated disces
Scattered arrangement of protein fibers
Dense irregular connective tissue
A characteristic of all epithelia
Which type of tissue contains a calcified ground substance & is specialized for structural support?
Bone connective tissue
Preventing desiccation & providing surface lubrication within a body cavity are the functions of?
Simple epithelium is adapted for what?
Diffusion & filtration
Does an epithelium serve as a packaging & binding material?
Which connective tissue type is composed of cells called chondrocytes & may be surrounded by a covering called perichondrium?
Which epithelial tissue type lines the trachea (air tube)?
Pseudostratified columnar epithelium
Which muscle type consists of long, cylindrical, striated cells with multiple nuclei located at the periphery of the cell?
A gland that releases its secretion by exocytosis into secretory vesicles is called ______gland
The epithelial type that is found in the lining of the lumen of the stomach
Simple columnar epithelium
The epithelial type that lines the oral cavity
Stratified squamous epithelium
Epithelial type that lines the urinary bladder
Epithelial that lines the tiny air sacs of the lungs
Simple squamous epithelium
What are the three secretion methods of exocrine glands
1) Merocrine glands
2) Holocrine glands
3) Apocrine glands
Package their secretions in structures (secretory vesicles), which travel to the apical surface of the glandular cell & release their secretion
Examples of Merocrine glands
Lacrimal (tear) glands, salivary glands, some sweat glands, the exocrine gland of the pancreas, & the gastric glands of the stomach
Some merocrine glands are also called
Holocrine glands form from
Cells that accumulate a product & then the entire cell disintegrates. A holocrine secretion is a mixture of cell fragments & the product the cell synthesized prior to its destruction. These secretions tend to be more viscous than merocrine secretions
An example of holocrine glands
The oil-producing glands (sebaceous glands) in the skin
Apocrine glands are composed of
Cells that accumulate their secretory products w/in the apical portion of their cytoplasm. Secretion follows as this apical portion decapitates. The apical portion of the cytoplasm begins to pinch off into the lumen of the gland for the secretory product to be transported to the skin surface
An example of apocrine glands are
Mammary glands & ceruminous glands
What characteristics are common to all connective tissues?
o Common origin - all arise from mesenchyme (an embryonic tissue)
o Three principle types of fiber found in connective tissues (Collagen, elastic fibers, reticular fibers)
o Extracellular matrix - comprised of nonliving extracellular matrix
What are the main structural differences between dense regular and dense irregular connective tissue?
Dense regular: Densely packed collagen fibers are parallel to direction of stress
Dense irregular: Densely packed collagen fibers are interwoven; fibers are irregularly clumped together & project in all directions
In what regions of the body would you expect to find hyaline cartilage, fibrocartilage, & elastic cartilage
* Hyaline cartilage found: Most of fetal skeleton; covers articular ends of long bones; costal cartilage; most of the larynx, trachea, & nose
* Fibrocartilage found: Intervertebral discs; pubic symphysis; menisci of knee joints
* Elastic cartilage found: External ear; epiglottis of the larynx
What are the similarities and differences between skeletal muscle, cardiac muscle, and smooth muscle?
* Skeletal muscle is striated & multiple nuclei. The muscle looks organized
* Cardiac muscle also may appear striated, but with only a single band crossing each bundle, the intercalated disc. Each cell possesses one or two, large, round nuclei, which stain fairly dark.
* Smooth muscle is not striated and each cell has only a single nucleus. The nuclei are elongated and dark-staining and the cells are less organized
What are the functions of the integumentary system?
2) Prevention of water loss
3) Temperature regulation
4) Metabolic regulation
5) Immune defense
6) Sensory reception
How does the integumentary system protect?
*Acts as a barrier & offers protection against harmful chemicals, toxins, microbes, & excessive heat or cold
*Skin is selectively permeable
How does the integumentary system prevent water loss?
*Epidermis is water resistant
*Water cannot easily enter/exit the skin unless secreted by sweat glands
How does the integumentary system regulate temperature?
Body temp is influenced by vast capillary networks & sweat glands in the dermis.
Describe metabolic regulation
Calcitriol is synthesized from cholecalciferol by some endocrine cells in the kidney. Calcitriol, the active form of vitamin D, is a hormone that promotes calcium & phosphorus absorption from ingested materials across the wall of the small intestine. Thus the synthesis of vitamin D is important in regulating the levels of calcium & phosphate in the blood
Describe the immune defense of the integumentary system
The epidermis contains a small population of immune cells (derived from a type of WBC). They play an important role in initiating an immune response by phagocytizing pathogens
Describe sensory reception
The skin contains numerous sensory receptors which are associated with nerve endings that detect heat, cold, touch, pressure, texture, & vibration
Describe excretion by the integumentary system
Skin exhibits an excretory function when it secretes substances from the body during sweating.
What are the various factors that determine skin color?
A combination of hemoglobin, melanin, & carotene
What are the various glands of skin?
The skin houses two types of exocrine glands:
1) Sweat (sudoriferous) glands-produce a watery solution that performs several specific functions
2) Sebaceous glands-produce an oily material that coats hair shafts & the epidermal surface
*A pigment produced & stored in cells called melanocytes.
*There are two types; eumelanin & pheomelanin
*They occur in various ratios of yellow, reddish, tan, brown, and black shades
*Transfered in membrane bound vesicles from melanocytes to keratinocytes in the stratum basal & stratum spinosum via phagocytosis or exocytosis
*The keratinocytes that receive the melanin are displaced toward the stratum corneum & thus melanocyte activity affects the color of the entire epidermis
*A yellow-orange pigment that is acquired in the body by eating various yellow-orange vegetables.
*accumulates inside keratinocytes of the stratum corneum & w/in the subcutaneous fat
*Converted into vitamin A
Sweat glands are
1) Merocrine sweat glands
2) Apocrine sweat glands
Ceruminous glands are
Modified sweat glands located only in the external acoustic meatus (external ear canal), where their secretion mixes with both sebum and exfoliated keratinocytes to form waterproof earwax called cerumen
*about 1000-2000 of these glands in the external acoustic
*help trap foreign particles or small insects & keep them from reaching the eardrum
Mammary glands of the breasts are
*Modified apocrine sweat glands.
*Both males & females have mammary glands, but these glands only become functional in pregnant females, when they produce a secretion (milk) that nourishes offspring
*The development of the gland & the production of its secretory products are controlled by a complex interaction between gonadal & pituitary hormones
What is acne
Describes plugged sebaceous ducts. Acne become abundant beginning at puberty, because increases in sex hormone levels stimulate sebaceous gland secretion, making the pores more prone to blockage
Composed of epidermis and dermis
The fingernails are formed from
Fibrous protein in epidermis
Receptors for touch
pigment forming cells
Most numerous epidermal cell
The epidermal dendritic cell is
A phagocytic cell (active in immune response)
Layer deep in dermis
Reticular layer is a
Dense irregular connective tissue
Smooth muscle attached to hair follicle
The layer of the epidermis in which cells begin the process of keratinization is the
The sweat glands that communicate with skin surfaces only in the axillary, areolar, pubic, & anal regions are
Is storing calcium in the dermis a function of the integument?
Which layers contain areolar connective tissue and dermal papilllae?
A pigment that accumulates inside keratinocytes
The layer of the epidermis in which cells begin the process of keratinization is the
Which epidermal cell type is responsible for detecting touch sensations?
tactile (Merkel) cell
Water loss due to evaporation of interstitial fluid through the surface of the skin is termed
What effect does the protein keratin have on both the appearance & the function of the integument?
The keratin found in epidermal cells of the skin are called cytokeratins. Their structure in these cells gives skin its strength & makes the epidermis almost waterproof.
A family of fibrous structural proteins that are both tough and insoluble
Describe two ways in which the skin helps regulate body temperature
*When the body is too warm and needs to dissipate heat, the diameter of the blood vessels in the dermis enlarges to permit more blood flow through the dermis, & sweat glands release fluid onto the skin surface. As relatively more blood flows through these dermal vessels, the warmth from the blood dissipates through the skin, & the body cools off by evaporation of the sweat
*When the body is cold and needs to conserve heat, the blood vessels in the dermis constrict to reduce blood flow. In an effort to conserve heat, more blood is shunted to deeper body tissues, & relatively less blood flows in the dermal blood vessels
List the layers of the epidermis from deep to superficial
Compare the structures of the epidermis layers
*Stratum corneum: Consists of about 20-30 layers of dead, flattened, anucleate, keratin-filled keratinocytes called corneocytes
*Stratum Lucidum: 2-3 layers of anucleate, dead cells; seen only in thick skin (palms, soles)
*Stratum granulosum: 3-5 layers of keratinocytes with distinct granules in the cytoplasm: keratinization begins in this layer
Stratum spinosum: Several layers of keratinocytes attached to neighbors by desmosomes: epidermal dendritic cells present
*Stratum Basale: Deepest single layer of cuboidal to low columnar cells in contact with basement membrane: mitosis occurs here: contains keratinocytes, melanocytes, & tactile cells
How do apocrine & merocrine sweat glands differ in structure & function?
Merocrine: Simple, coiled, tubular glands that release their secretion onto the surface of the skin (palms, forehead, soles).
Apocrine: Simple, coiled, tubular glands that release their secretion into hair follicles at the axillae, areola, pubic region, anal region. The secretory portion has a larger lumen that the merocrine gland
Describe how the skin is involved in Vitamin D production
Vitamin D3 is a cholesterol derivative synthesized from cholecalciferol which is produced by some epidermal cells when they are exposed to ultraviolet radiation.