Histo I: Connective, muscle and neural tissues Flashcards
name the 2 types of connective tissue proper
fibrous connective tissue and special (connective with special features)
name the 2 types of fibrous connective tissue
loose connective and dense connective
name the 2 types of dense connective tissue
dense regular connective tissue and dense irregular connective tissue
name 4 types of special connective tissues
mesenchymal-, gelatinous- (mucous), reticular-, and adipose connective tissue
categories of adipose tissue
white and brown
name connective tissue fibers (3)
Collagen fibers, Elastic fibers, Reticular fibers
name connective tissue ground substances (3)
Proteoglycans, Glycoproteins, Glycosaminoglycans
name as many types of connective tissue cells as you can
Fibroblasts and fibrocytes, Blood cells, Plasma cells, Macrophages (histiocytes), Mast cells, Pigment cells (melanocytes), Fat cells (lipocytes, adipocytes), Pericytes
What are fibroblasts?
Fibroblasts are the most common type of connective tissue cell.
Are immature flattened cells responsible for the formation of fibers (collagen, elastic and reticular) and the amorphous material.
Describe the morphology of fibroblasts.
They are irregularly shaped and have several short, thick processes.
What are fibrocytes?
Fibrocytes are mature, slender, spindle-shaped or flattened connective tissue cells that produce connective tissue proteins such as collagen.
Describe the morphology of fibrocytes.
Have long, thin processes and poorly developed organelles.
What are macrophages?
Or histiocytes - are a type of phagocytic dense, fibrous connective tissue formed from monocytes.
Describe the morphology of histiocytes.
Relatively large cells with irregular outline. Nucleus is spherical or ellipsoidal; cytoplasm contain well-developed Golgi complex and a variable number of lysosomes.
What do the granules of mast cells contain?
The granules of mast cells contain heparin (inhibits blood coagulation) and histamine (involved in local inflammatory reactions and edema by increasing capillary permeability).
Describe the morphology of mast cells.
Rounded or elongated form. The nucleus is relatively small, cytoplasm contain large number of granules which stain with basic dyes
What are mast cells?
A type of white blood cell that are found in connective tissues.
Contribute to homeostasis in the immune system, serve as a first line of defense against antigens.
What are plasma cells?
A plasma cell is a type of white blood cell/immune cell. Develop from activated B cells.
Describe the morphology of plasma cells.
Ovoid cells, abundant cytoplasm, nucleus is spherical and eccentric. Cytoplasm is basophilic because highly developed granular endoplasmic reticulum (ergastoplasm).
What is the function of plasma cells?
Their function is to produce antibodies and, thus, they are actively involved in the defense of the organism.
What are adipocytes?
Fat cells, a type of connective tissue.
Describe the morphology of adipocytes.
Contain droplets of fat. Narrow rim of cytoplasm contains flattened nucleus and organelles.
What are melanocytes?
Pigment cells that contain granules of melanin.
What are pericytes?
Are multipotential connective tissue progenitors which are able to differentiate into a variety of cells; osteoblasts, chondrocytes and fibroblasts.
Describe collagen fibers.
Composed of protein collagen, have great tensile strength, are inelastic, measure between 1-10 µm in thickness and are of indefinite length.
Describe elastic fibers.
Composed of protein elastin, less strong than collagen; stretch easily but return to their original length when stretching force is removed.
Branch and anastomose to form networks.
What are reticular fibers?
Very thin collagen fibers
Purpose of Amorphous material, or ground substance?
The material in which the cells and the fibers are embedded.
Permits diffusion of fluids containing nutrients and waste products between blood and lymph capillaries and cells.
Gel-like nature provides support for the tissue.
Describe loose connective tissue.
Very common; delicate consistency, flexible and well vascularized.
What is the function of loose connective tissue?
Supports epithelia, surrounds blood vessels.
Fills spaces between muscle and nerve fibers.
Where is loose connective tissue found?
Papillary layer of dermis; hypodermis
Describe dense irregular connective tissue.
Dense and irregular,
fewer cells than in loose connective tissue;
predominance of collagen fibers arranged without clear orientation,
less flexible, but more resistant to stress.
Where is dense irregular connective tissue found?
Dermis (lower layers of the skin) and in sclera.
Describe dense regular connective tissue.
Dense regular; collagen bundles are arranged in parallel array. Great resistance to traction forces.
Where is dense regular connective tissue found?
Tendons and ligaments
Describe mesenchyme.
Mesenchyme is embryonic undifferentiated loose connective tissue made up of spindle-shaped cells.
Extracellular matrix is occupied by viscous ground substance; reticular collagen fibers are fine and relatively sparse.
Describe mucous connective tissues.
Abundant gelatin-like ground substance -> “Wharton’s jelly”, thin collagen fibers.
Function of mesenchyme?
During embryogenesis, mesenchyme gives rise to the body’s connective tissues.
Loose nature of cells allows the tissue to move and to be molded.
Function of mucous connective tissues?
Embryonic connective tissue.
Where is mucous connective tissues found?
Umbilical cord
Describe reticular connective tissue.
Reticular fibers form 3D network that supports the reticular tissue (reticular cells + reticular fibers).
Function of reticular connective tissue?
Creates special microenvironment for hemopoietic and lymphoid organs.
Where is reticular connective tissue found?
Bone marrow, spleen, lymph nodes
What is the mononuclear phagocytic system?
A system and family of cells comprising; bone marrow progenitors, osteroclasts, monocytes and tissue macrophages /histiocytes.
Function of mononuclear phagocytic system?
Main function is phagocytosis.
Tissue repair and remodeling, resolution of inflammation, maintenance of homeostasis, and disease progression.
Name 3 types of cartilages.
hyaline cartilage
elastic cartilage
fibrous cartilage (fibrocartilage)
Name 2 types of bone material.
lamellar bone (compact and spongy or cancellous bones) woven bone (fibrous bone)
What is cartilage tissue composed of?
chondrocytes
Where are chondrocytes located in cartilage?
Chondrocytes are dispersed in the extracellular matrix within lacunae.
Describe the extracellular matrix of cartilage.
Extracellular matrix of cartilage consists of fibers, which are embedded in the ground substance.
How does cartilaginous tissue gain nutrients?
Nutrients have to be diffused from the vessels surrounding the cartilage by osmosis
In the ground substance where do chondrocytes lie?
In special cavities – cartilage spaces or lacunae.
What does ground substance form around lacunae?
Thin cartilage capsules or capsular matrix around lacunae. Differ from the rest of ground substance in staining properties.
What is hyaline cartilage?
The most common type of the cartilage tissue of the body.
Where is hyaline cartilage found?
Hyaline cartilage is found in the skeleton of the embryo, costal cartilages, nose, larynx, trachea, bronchi of the respiratory system and covers articular surfaces.
Where are isogenous groups and territorial matrixes found?
hyaline cartilage and elastic cartilage
What are territorial matrixes?
A region just around the chondrocyte containing lacunae, surrounds the isogenous group.
What are isogenous groups?
Clusters of chondrocytes situated in lacunae (usually 2-4 cells per group).
Describe elastic cartilage.
Elastic cartilage contains large number of elastic fiber along with collagen fibers, is very flexible.
Elastic fibers are especially densely packed around the lacunae; chondrocytes are placed in lacunae in pairs or singly.
Where is elastic cartilage found?
External ear, epiglottis, larynx and in cartilage plates of small bronchi.
What is fibrocartilage?
Transitional form between dense connective tissue and hyaline cartilage.
Describe fibrocartilage.
Fibrocartilage has a large number of collagen fibers embedded in small amount of amorphous substance.
The chondrocytes lie singly or in pairs in lacunae.
Where can fibrocartilage be found?
Mainly in intervertebral disks, in articular discs; certain sites where tendon attaches to the bone.
What does bone tissue consist of?
Bone cells (osteoblasts, osteocytes, osteoclasts), extracellular matrix in which both collagenous fibers and ground substance are mineralized.
The hardness of a bone is caused by presence of what?
calcium phosphate (the slight elasticity is caused by the presence of collagen fibers)
What are osteoblasts?
The bone-forming cells, i.e. they synthesize and secrete bone matrix.
What are osteocytes?
True bone cells that reside within the lacuna of the mineralized bone matrix.
What are osteoclasts?
the bone-resorbing cells
Name 2 types of lamellar bone.
Compact bone and cancellous (trabecular) or spongy bone
Where can compact bone be found?
in the diaphyses of long bones and in outer layer of flat bones.
Where can cancellous bone be found?
in the epiphyses of long bones, and in the middle part of flat bones.
What is the Haversian system?
Otherwise known as osteons:
a series of tubes around narrow channels formed by lamellae.
The Haversian canals surround blood vessels and nerve fibers throughout the bone and communicate with osteocytes.
The canals and the surrounding lamellae are called a Haversian system (or an osteon).
What is an osteon?
The chief structural unit of compact (lamellar) bone, consisting of concentric bone layers called lamellae, which surround the long hollow passageway, the Haversian canal.
What does compact bone consist of?
osteons or Haversian system
What does spongy bone consist of?
spicules (does not form the Haversian system)
What is lamellae bone?
Each osteon consists of concentric layers, or lamellae, of compact bone tissue that surround a central canal, the haversian canal.
What is the periosteum?
Is a thin layer of dense connective tissue covering bones.
(consists of inner and outer layer: inner layer contains osteoblasts during the growth period of bones, outer layer consists mainly of longitudinally oriented collagenous fibers)
What is the endosteum?
The endosteum lines the marrow cavity as well as the small cavities in the spongy bone.
(It is much thinner than periosteum and is composed of a single layer of flattened cells.)
Name 2 ways bone can form.
Directly from mesenchyme - > intramembranous ossification,
or endochondral ossification.
Describe endochondral ossification.
Bone formation by means of replacing (hyaline) cartilage with bone tissue.
Describe intramembranous ossification.
The process of bone development from fibrous membranes.
Bone formation directly from mesenchyme in fibrous membranes.
flat bones, like skull and face, mandible, and clavicle
What is epiphyseal plate?
The growth plate, is a thin layer of cartilage that lies between the epiphyses and metaphyses, and is where the growth of long bones takes place.
example of endochondral ossification
Name 4 zones of the epiphyseal plate.
Resting zone, Proliferative zone, Hypertrophic zone, Ossifying zone
Describe the steps of endochondral ossification.
periosteal collar forms at bone diaphysis,
ossification center forms,
then mesenchymal tissue grows through collar,
forms periosteal bud,
then those cells differentiate into osteoblasts and
ossification begins
what is muscle tissue characterized by?
contractability by way of myofilaments actin and myosin
name the 2 types of cardiac myofilament
actin and myosin
name the 3 types of muscle tissue
smooth, skeletal and cardiac
muscle cell cytoplasm is called?
sarcoplasm
muscle cell membrane is called?
sarcolemma
muscle cell’s endoplasmic reticulum is called?
sarcoplasmic reticulum
where is smooth muscle tissue found?
mostly within the visceral wall of organs
describe the morphology of smooth muscle cells
non-striated, one nucleus, elongated fusiform
smooth muscle cells consist of?
actin, myosin and intermediate filaments
describe the morphology of skeletal muscle cells
elongated fusiform cells, one nucleus
describe smooth muscle tissue
non.striated and they gen. occur as bundles or sheets of elongated fusiform cells with tapered ends, involuntary control
what does fusiform mean
having a spindle-like shape that is wide in the middle and tapers at both ends
describe skeletal muscle tissue
striated, voluntary control, consists of fibers, lots of flattened nuclei, contains myofilaments actin and myosin
what is a myofibril
bundles of protein filaments that contain the contractile elements of the cardiomyocyte
describe a-bands
anisotropic - darkly stained containing myosin (myosin itself is thick), length is constant
describe i-bands
isotropic - lightly stained containing actin (actin itself is thin), shortens during contraction
describe skeletal muscle development
myoblasts and satellite cell fuse to form primary myotube -> mature multinucleated muscle fiber
muscle fibers divided into what 3 types?
red, white and intermediate fibers
describe cardiac muscle tissue
consists of individual and elongated and branched cardiomyocytes which are connected by intercalated discs - cross-striated, anastomosing
what are satellite cells responsible for?
skeletal muscle regeneration
what are specialized cardiac muscle cells called? and function?
cardiac conducting cells
and function is heartbeat regulation and coordination
what are the 2 principle types of nervous tissue?
neurons (nerve cells) and neuroglia cells (supporting cells)
what are the 3 general categories of nerve cells?
sensory-, motor- and interneurons
sensory neuron function?
convey impulses from receptors to CNS
motor neuron function?
convey impulses from CNS to effector cells
interneuron function?
form communication network between motor- and sensory neurons
name the functional components of a nerve cell
cell body(or perikaryon), axon, dendrites and synaptic junction
another word for neuron cell body
perikaryon
describe neuron morphology
large nucleus with single prominent nucleolus; longest process is single axon; shorter, multiple processes = dendrites
axon transmission direction?
away from perikaryon
dendrites’ transmission direction?
from periphery toward cell body
what terminal of a neuron makes contact with other neurons?
synapse
according to process morphology, neurons are divided into what groups
unipolar, pseudopolar, bipolar and multipolar neurons
what can be found in neuron cytoplasm?
Nissl bodies or substance
what are Nissl bodies?
granules of rough endoplasmic reticulum
what are neuroglia?
supportive nerve cells that are nonexcitable/ do not conduct impulses
name the 3 types of macroglia
astrocytes, oligodendrocytes, schwann cells
name different types of neuroglia
macroglia, microglia, ependymal cells
how does a myelin sheath develop?
from compacted schwann cell cytoplasm layers wrapped concentrically around axon
(in CNS myelin sheath is produced by oligodendrocytes)
name the 2 types of sensory nerve endings
nonencapsulated receptors and encapsulated receptors
name the 2 types of nonencapsulated receptors
Merkel’s discs (in hairless skin) and hair plexus (in hair follicles)
name the 2 types of encapsulated receptors
Pacinian corpuscle (in various places eg. dermis, pleura) and
Meisner’s corpuscle (fingers/feet, genitals)
