Histology

Question 1

What kind of connective tissue do we have?

Answer 1

Blood
Bone
Cartilage
Connective tissue proper

Question 2

Connective tissue proper forms? Groups

Answer 2

Loose and dense connective tissue

Loose:

• Areolar
• Adipose
• Reticular

Dense

• Regular
• Irregular
• Elastic

Question 3

what types of cartilage do we have?

Answer 3

Fibrocartilage
Hyaline cartilage
Elastic cartilage

Question 4

Carrtilage are rich in which ground substance?

Answer 4

Proteoglycans and hyaluronic acid (good lubricant) -> traps loots of water -> Good recoil after stress

Also contain adhesive molecules: Hold proteoglycan aggregates togheter. Chondronection in cartilate, osteonectin in bone and fibronectin in fibrous tissue

Question 5

What is the name of the structure that link cardiomyocytes togheter?

Answer 5

Intercalated disc

Question 6

What is a tissue?

Answer 6

A cluster of cells with similar structure and function, working as a unit

Question 7

What are the 4 groups of tissue?

Answer 7

Connective tissue
Neural tissue
Muscle tissue
Epithelial tissue

Question 8

What does pseudostratified epithelium mean and where can it be found?

Answer 8

These are simple columnar epithelial cells whose nuclei appear at different heights, giving the misleading (hence “pseudo”) impression that the epithelium is stratified when the cells are viewed in cross section. Pseudostratified epithelium can also possess fine hair-like extensions of their apical (luminal) membrane called cilia. In this case, the epithelium is described as “ciliated” pseudostratified epithelium. Cilia are capable of energy dependent pulsatile beating in a certain direction through interaction of cytoskeletal microtubules and connecting structural proteins and enzymes. In the respiratory tract the wafting effect produced causes mucus secreted locally by the goblet cells (to lubricate and to trap pathogens and particles) to flow in that direction (typically out of the body). Ciliated epithelium is found in the airways (nose, bronchi), but is also found in the uterus and Fallopian tubes of females, where the cilia propel the ovum to the uterus.

Pseudostratified epithelium; this is also called respiratory epithelium as it is almost exclusively confined to the larger respiratory airways of the nasal cavity, trachea and bronchi.

Respiratory epithelium is a type of epithelium found lining the respiratory tract, where it serves to moisten and protect the airways. It also functions as a barrier to potential pathogens and foreign particles, preventing infection and tissue injury by action of the mucociliary escalator.

Epididymis and respiratory epithelium

Question 9

What 3 types of secretion do we have and what are their function?

Answer 9

Merocrine, apocrine and holocrine.

Merocrine: Protein
Apocrine: Protein + some of its plasma membrane (lactation)
Holocrine: Hole cell dies and release its content (sebacous gland)

Question 10

What is the name of the 5 layers in stratified squamous keritinized epithelium?

Answer 10

Stratum basale
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum

Question 11

What cell type is present in the outer skin?

Answer 11

Keratinocytes, melanocytes (make melanin), langerhans cells (antigen presenting cells), merkel`s cells (touch receptors, slow adapting)

All cells are found in stratum basale except langerhans cells which is found in stratum spinosum

Question 12

Dermis constists of two layers, which?

Answer 12

Stratum papillare (papillary layer)
Stratum reticulare (reticular layer)

The papillary region is composed of loose areolar connective tissue. This is named for its fingerlike projections called papillae, th extend toward the epidermis and contain either terminal networks of blood capillaries or tactile Meissner’s corpuscles (sensitivity to light touch, rapid adapting cells)

The reticular dermis is the lower layer of the dermis, found under the papillary dermis, composed of dense irregular connective tissue featuring densely packed collagen fibers. It is the primary location of dermal elastic fibers.

The reticular region is usually much thicker than the overlying papillary dermis. It receives its name from the dense concentration of collagenous, elastic, and reticular fibers that weave throughout it. These protein fibers give the dermis its properties of strength, extensibility, and elasticity. Within the reticular region are the roots of the hair, sebaceous glands, sweat glands, receptors, nails, and blood vessels. The orientation of collagen fibers within the reticular dermis creates lines of tension called Langer’s lines, which are of some relevance in surgery and wound healing

Question 13

What is the structure of hair form inner to outer?

Answer 13

Central medulla, cortex and cutile (keratinized)

Hair grow from the hair bulb in follicle -> reach out towards the outer surface as hair root -> hair shaft (the one outside the skin).

Arrector pili and sebacous gland

Question 14

Name some parts of structures of nails

Answer 14

Free edge
Body (the visable attached portion)
Root of nail embedded in skin
Cuticle is the proximal nail fold that projects onto the nail body

Question 15

What are the major parts of long bone?

Answer 15

Compact and spongy bone

Epiphysis and diaphysis

Compact bone: Endosteum, periosteum, compact bone in the middle.

Perioesteum: outer firbous sheath of dense regular tissue (except at the articular surfaces). Two layers: Puter fibrous layer, inner celluar layer with osteoprogenic cells

Question 16

What forms a osteon?

Answer 16

The osteon or haversian system is the smallest fundamental functional unit of much compact bone. Osteons are roughly cylindrical structures.

Each osteon consists of concentric layers, or lamellae, of compact bone tissue that surround a central canal, the haversian canal. The haversian canal contains the bone’s blood supplies. The boundary of an osteon is the cement line.

Near the surface of the compact bone, the lamellae are arranged parallel to the surface; these are called circumferential lamellae (inner and outer)

The collagen fiber density is lowest at the seams between lamellae, accounting for the distinctive microscopic appearance of a transverse section of osteons. The space between osteons is occupied by interstitial lamellae, which are the remnants of osteons that were partially resorbed during the process of bone remodeling.

Volkmanns canal have a perpendicular angle as the haversian canal

Question 17

Hemidesmosomes

Answer 17

Link cells to its basement membrane in its basal surface

Question 18

Macula adherens and zonula occudens

Zonula adherens

Answer 18

Desmosomes and thigh junction

Question 19

Exocrine glands can be divided into?

Answer 19

Simple gland: single unbranded duct (tubular or alveolar)

Complex glands: branched duct system

Question 20

Endocrine glands are?

Answer 20

Ductless glands

Question 21

What is special for fibrocartilage and where can we find it?

Answer 21

No perichondrium

Chondrocytes are arranged in rows, following the orientation of stress

Intervertebral disc
Some articular cartilages
Pubic symphysis
Joint capsule

Question 22

Where can we find satellite cells in PNS?

Answer 22

Around ganglion cells. Function is similar to Schwann cell, except that it does not make myelin.

Question 23

What types of central neuroglia do we have?

Answer 23

Astrocytes
Oligodendocytes
Microglia
Ependymal cells

Question 24

Where are fibrous and protoplasmic astrocytes found?

Answer 24

Fibrous - white matter
Protoplasmic - gray matter

Glial fibrillary acidic protein is used to detect them (antibodies)

Question 25

Haemotoxylin stains what?

Answer 25

Hematoxylin is a positively charged, blue dye complex. It stains with high affinity basophilic structures.

The overall blue color shows a general staining of the specimen with hematoxylin. At higher magnification, structures with a range of staining intensities become evident. Nuclei are the most intensely stained. Individual cells are easily identified because of lightly stained structures in the cytoplasm of most cells. Cells rich in proteins and rER have more blue colour.

Hematoxylin binds to negatively charged complexes of condensed DNA and histones (i.e., heterochromatin)

Basic dyes have a net positive charge and bind to components of cells and tissues that are negatively charged.

• Phosphate groups of nucleic acids (DNA and RNA)
• Sulfate groups of some polysaccharides (glycosaminoglycans) and some proteins (mucus).

Tissue components that stain with basic dyes are referred to as basophilic

Question 26

Eosin stains what?

Answer 26

Eosin is a negatively charged, pink dye. It stains with high affinity acidophilic (also known as eosinophilic) structures.

The overall pink color shows a general staining of the specimen with eosin. At higher magnification, the range of staining intensities is much less than with hematoxylin. The lightly stained nuclei are much less conspicuous. In contrast, the cytoplasm of most cells is intensely stained.

Eosin binds to positively charged proteins in the cytoplasm.

Acidic dyes have a net negative charge and bind to components of cells and tissues that are positively charged.

• Ionized amino groups in proteins (side chains of lysine and arginine).

Tissue components that stain with acid dyes are referred to as acidophilic.

Question 27

Paneth cells do what and can be found where?

Answer 27

In the deep part of the crypt of liberkuhn in te small intestine

Secreate antibacterial substances (lysosomes)

Question 28

We have 3 different gastric glands, which?

Answer 28

Cardiac, fund and pyloric

Question 29

Villi consists of what? microstructure

Answer 29

Capillaries (countercurrent), lacunae (central one), lots of lymphocytes and macrophages, myofibroblast and smooth muscles.

Villi are extensions of the lamina propria. Remember that each enterocyte have microvilli (brush border)

we also have goblet cells and a basement membrane

Question 30

High endothelial venues are important in?

Answer 30

Enable lymphocytes (B and T) to move out from the blood to the lymph nodes where they can try to find its unique antigen. This occurs in the parafolicular area.

They can only move out, NOT the other way around.