Histology Study Guide

Nucleus

contains the genetic material of the cell and is limited by a lipid membrane

Histone protein

majority of DNA-associated protein controlling DNA coiling and gene expression

Non-histone protein

Mainly enzymes for synthesis of DNA of DNA, regulatory proteins

Heterochromatin

electron dense, tightly coiled DNA, NOT actively transcribing RNA, occurs as clumps along periphery

Euchromatin

electron-lucent, uncoiled DNA, actively transcribing RNA, occurs amidst the nucleoplasm

plasma membrane

the cell's interface with the environment, made up of a bi-layer of phospholipids with embedded proteins

Rough endoplasmic reticulum

organelle studded with ribosomes, where proteins destined for export or incorporation into lysosomes (enzymes) are made

smooth endoplasmic reticulum

organelle that has no ribosomes and is where cholesterol and phospholipid synthesis occurs

mitochondria

organelle responsible for energy (ATP) production

golgi apparatus

major organelle involved with cell secretions, responsible for exocytosis of proteins and large MW secretory proteins, packaging membrane-bound vesicles to fuse with plasma membrane, lysosome formations, modification of proteins, formation of membrane glycolipids, and recycling of membrane. Also closely associated with rough ER

centriole

function as the organizing center for microtubles of the cytoskeleton. i.e. helps control chromosomes during cell division.

centrosome

a pair of centrioles

phospholipid bilayer, proteins, glycocalyx

what are the major components of the plasma membrane?

prevents packing of hydrophobic ends of phospholipids

what is cholesterol's role in the plasma membrane?

head

what part of the phospholipid faces to the outsides of the membrane? (i.e. which part is polar?)

tails

What part of the phospholipid faces to the inside of the membrane? (i.e. which part is nonpolar?)

glycocalyx

The external surface of a plasma membrane that is important for cell-to-cell communication, composed of polysaccharides

transcription, mRNA processing, translation

What are the three major steps of protein synthesis?

ribosomes

organelle responsible for the translation of mRNA to amino acid sequences/proteins

True

True or False: ribosomes can function free in the cytoplasm and attached to the rough ER

nucleus

where does transcription occur?

cytoplasm

where does translation occur?

exocytosis

bulk transport out of the cytoplasm

endocytosis

bulk transport into the cytoplasm

phagocytosis

process in which a cell ingests and kills a pathogenic organism (particularly bacteria)

receptor-mediated endocytosis

Process by which cells take in specific molecules for which the cell has a specific receptor.

clathrin

a protein that plays a major role in the formation of coated vesicles

ATP

the end product of cellular metabolism starting with glucose, produced in the mitochondria

aerobic respiration

Mitochondrial respiration that requires a continuous supply of oxygen

matrix and inner membrane

where does aerobic respiration take place in the mitochondrion?

mitosis

ultimately yields 2 identical diploid daughter cells with a full complement of chromosomes

prophase

stage of mitosis when two chromosomes are first visible

metaphase

stage of mitosis when chromatids attach to kinetochore and arrange along equatorial plate

Anaphase

stage of mitosis when centromeres are split and chromatids begin to migrate to opposite ends of the cell

Telophase

stage of mitosis when chromosomes uncoil, nuclear envelope forms, and when cytokinesis and cytoplasmic division is imminent

M phase

the mitotic phase of the cell cycle

G1 phase

the longest phase of the cell cycle, variable by cell type. When cells grow, differentiate, and perform their functions

G2 phase

Phase of the cell cycle when the cytoplasm and nucleus is prepared for mitosis

S phase

phase of the cell cycle when the nuclear DNA is replicated

G0 phase

stage of the cell cycle when the cell is continuously differentiated and is no longer capable of re-entering S phase for mitosis

Interphase

phase of the cell cycle that represents the non-dividing phases (G1, S, G2)

Meiosis

yields 4 haploid gametes that each contain half the complement of chromosomes, involves one replication of chromatin followed by 2 sequential cell divisions

germ cells

Cells that undergo meiosis

chiasma formation

crossing over (exchange) of genetic material between chromatids to mix up maternal and paternal alleles and contribute to genetic diversity

microfilaments

5nm in diameter, consists of actin, associated with transmembrane proteins of plasma membrane to form a supporting meshwork called the cell cortex

intermediate filaments

10-12nm in diameter, stable, self assemble into larger filaments and bind structures to each other and to membrane proteins, specific to various cells, structural

microtubules

25nm in diameter, globular proteins, assembled and disassembled to provide for alterations in cell shape and the position of organelles, important for support and movement of cilia and cell division.

cilia

motile specialized hair-like cell structures found on the apical surface of simple epithelium

respiratory tract epithelium, ependymal cells lining ventricles in CNS, reproductive tract

where are some locations that you may find cilia?

microvilli

finger-like projections of the plasma membrane supported by actin filaments that act to increase surface area for the purpose of absorption

small intestine, proximal renal tubes, and choroid plexus cells in CNS

where would you typically find microvilli?

goblet cells

modified columnar epithelial cell found in the respiratory and intestinal tracts, which secretes the main component of mucus

connective tissue

consists of cells separated by an abundance of intercellular material, e.g. fibers and ground substance

cells and extracellular matrix

What are the two major components that make up connective tissue?

extracellular matrix

What is the dominant component of connective tissues that determines the physical properties of the tissue?

collagen

most abundant fiber/most abundant protein in the body

Type I collagen

fibrous CT arranged in high-tensile strength bundles of fibrils (e.g. dermis, tendon, ligaments, bone)

Type I collagen

most abundant collagen

27

How many types of collagen are there?

Type III collagen

reticulin, forms the fine network of fibers supporting highly cellular tissues (e.g. liver, bone marrow, lymphoid organs)

Elastin

arranged as short, branching fibers or as discontinuous sheets, found in skin, lung, and blood vessels, has high capacity for stretch and recoil

Ground substance

amorphous transparent extracellular material forming semi-fluid gel that fills space between cells and fibers

glycosaminoglycans

substance that makes up ground substance

Hyaluronic acid

the predominant GAG in loose CT

structural glycoproteins

group of molecules composed principally of protein chains bound to branched polysaccharides

Basement membrane

sheets of ECM proteins that act as the interface between connective tissues and the parenchymal and epithelial cells that they support

lamina lucida

electron-lucent, interfaces with membrane of basal cells

lamina densa

electron-dense intermediate layer of basement membrane

lamina fibroreticularis

relatively electron-lucent broad layer that merges with underlying supporting connective tissue; consists of collagen type III

fibroblast

most common connective tissue cell, elongate, spindle-shaped, or stellate, synthesizes tropocollagen and will repair connective tissue by phagocytizing and recycling old collagen

adipocyte

cells adapted for the storage and processing of fat

white adipose tissue

adipose tissue distributed throughout the body particularly in deep layers of skin with a rich blood supply that serves as a thermal insulator and cushion against mechanical shock

brown adipose tissue

highly specialized adipose tissue found in newborn mammals and some hibernating animals that is important in body temperature regulation and characterized by expression of a unique uncoupling protein termed UCPI (thermogenin)

Chondrocyte

mature cell of cartilage, maintains the cartilage matrix, located in spaces in matrix called lacunae

Chondroblast

cartilage-forming cells, produces ground substance, capable of mitosis, participates in growth of cartilage

perichondrium

surrounding layer of collagen fibers and spindle-shaped fibroblastic cells in cartilage

Hyaline cartilage

most common type of cartilage, seen in growth plates of bones and joints, matrix consists of collagen type II dispersed in interlacing network, chondrocytes have small nuclei with dispersed chromatin and basophilic granular cytoplasm that reside in lacunae.

elastic cartilage

cartilage with abundant elastic fibers and elastin, collagen also present disposed between elastic fibers

fibrocartilage

features intermediate between cartilage and dense fibrous connective tissues; alternating layers of hyaline cartilage matrix and thick layers of dense collagen fibers oriented in the direction of functional stress, has a high tensile and compressive strength.

Collagen type I

organic matrix of bone is approximately 90% of this collagen

osteoblast

responsible for bone formation, synthesizes osteoid, located along the edges of bony trabeculae

Osteocyte

resting stage of the osteoblast trapped in matrix

Osteoclast

multinucleated giant cell that resides in depressions on surface of bony trabeculae, derived from monocyte lineage and function along with osteoblasts in the constant turnover and remodeling of bone

Woven bone

immature bone that consists of random weaves of collagen fibers and ground substance in the osteoid, the first bone to be deposited during repair of a fracture

lamellar bone

virtually all bone in the healthy adult, composed of regular parallel bands of collagen arranged in sheets

compact bone

bone tissue that forms the dense walls of the diaphysis

cancellous bone

bone tissue that consists of a network of fine, irregular trabeculae occupying the central cavity

Periosteum

fibrous CT that covers the external surface of bone

endosteum

delicate layer of inactive osteoblasts covering the trabeculae of cancellous bone

Endochondral ossification

proliferation of cartilage at the epiphyseal aspect of a growth plate that results in progressive elongation, and at the diaphyseal aspect of the growth plate, the cartilage is replaced by bone

contraction and movement

What is the dominant function of muscle tissue?

actin and myosin

What two proteins cause the contraction of muscles?

Skeletal muscle

what muscle type is voluntary and striated as well as highly contractile?

fasciculi

bundled groups of fibers

endomysium

fine CT support network within fasciculi

perimysium

connective tissue surrounding each fascicle

epimysium

dense collagenous sheath surrounding fascicles, essentially surrounds the muscle

myotubes

result when myoblasts proliferate and fuse end-to-end to form progressively longer multinucleate cells

myoblasts

immature muscle cells that differentiate from mesenchymal cells

Satellite cells

stem cells between basal lamina and cell membrane and act as resting myoblasts