2.3 Tissues

Question 1

what are the 4 types of tissues

Answer 1

epithelial, connecive, nerve and muscle

Question 2

what are the characteristics of Epithelial Tissue

Answer 2

1. Polarity
   
   • Apilcal surfaces: can have microvilli or villia
   • basement membrane: involved in anchoring epithelial later, acts as selective filter
     
     • contains basal lamina: mostly glycoproteins and collagen secreted by epithelial cells
     • reticular lamina: fine network of collagen and fibronectin fibers secreted by the underlying ECM
2. Special contacts
   
   • tight junctions and desmosomes
3. Supported by connective itssue
   
   • all epithelial sheets rest on supporting connective itssue
     
     • provides nutrients, site for waste prod exchance
4. aascular but innervated
   
   • contains no blood vessels but supplied by nerve fibers
5. Regenerative
   
   • Rapidly replaces lost cells by cell division

Question 3

what are the different types of Epithelial Tissues?

Answer 3

1. Simple vs Stratefied
   
   • simple: typical where abs and filtration occur (lining of lungs)
     
     • only one layer
   • Stratified: common highly abrasive areas (skin, esophagus)
     
     • want highly regenerative layer thats always adding more layers to skin
2. Squamous, cuboidal or columnar
   
   1. squamous: cells and nucleus are flattened (ex skin, blood vessels)
   2. cuboidal: round nucleus (ex kidney tubules)
   3. Columnar: upright elongated nucelus (ex intestines)

Question 4

what type of tissue is this

Answer 4

simple cuboidal epethelial

• nuceli relatively round and only one layer

Question 5

what type of tissue is this

Answer 5

simple columnar epethelial tissue

Question 6

what is the role of simple columnar epethelial tissue, where are they found

Answer 6

• function absorption, secretion of musuc, enzymes and toher substances
• can be cilliated or non cilliated

non cilliated type: lines most of digestive tract, gallbladder and excretory ducts, some glands

cilliated: line small bronchi, uterine tubes, some regions of uterus

* can contain goblet cells of mucus

Question 7

where cna you find simple cuboidal epithelia tissue?

Answer 7

can find in kidney tubules. duct and secretory protions of small glands, overay surface

*function is for secretion and absorption

Question 8

what mofoications are made to the epithelia of the digestive tract?

Answer 8

* talking about simple columnar

• have two modifications:
  1. dense microvilli: on paical surface of absorptive cells
  2. goblet cells: that secrete a protective lubricating mucus

Question 9

what are pseudostratified columnar?

Answer 9

• cells vary in hieght, but all cells rest on basement membrane however some do not reach the free surface

*simple in nature but look multilayered, not actually stratified

• because nuclei are seen at different layers it gives the false pseudo impression that there are several layers

Noncilliated type: in males sperm carying ducts and ducts of large glands

ciliated: lines trachea, most of upper respiratory tract

Question 11

describe stratified squamous epithelia

Answer 11

• thick membrane composed of several cell layers
• basal cells are suboidal or columnar and metabolically active, surface cells are flattened (squamous)
• function: underlying tissues in areas subjected to abrasion

Nonkeratinized type forms the moist linings of the esophagus, mounth, vagina

keratinized: forms epidermid of skin, dry membrane

Question 12

describe stratified cuboidal

Answer 12

• cuboidally shaped cells arranged in multiple layers
• protect areas as ducts of sweat glands, male urethra and mammary glands
• typically two cell layers thick, quite rare in body

*look to see the two layers, thats how you know its not the simple cuboidal like those in kidney

Question 13

describe stratified columnar

Answer 13

• also occurs at transition areas between two other types of epithelia
• some exocrine glands have areas of stratified columnar epithelium

*also in anoractal junction, pharynx and male urethra

• nuceli elongated and overall rectangular in shape
• as hint look for cillia, if see cillia its pseudostratefied

-

Question 14

describe transitional epithelia

Answer 14

Appearance of cuboidal and squamus, Depends on strucutre of tissue at that time

When bladder is empty looks cuboidal when full looks squamous

Found in lining of ureter, bladder

*basal cells cuboidal or columnar, suface cells dome shaped or squamours like depending on degree of stretch

*lines uteters bladder and part of urethra

** if has more than two layers it cant be stratefied cuboidal, so if more than two alyers and look cuboidal its transitional

Question 15

describe the cutaneous membrane

Answer 15

Cutaneous - Parts you can see visually

Dry mem bc exposed to outside of the body (skin)

Combo of stratified squamous and underlying connective tissue

Question 16

describe the mucous epithelial membrane

Answer 16

• mucosae line body cavities that open to the exterior
• mucous membranes are often adapted for absorption and secretion
• digestive and respiratory tracts secrete copious amounts of lubricating mucus
• urinary tract does not have any secretion but mucus membrane is bathed in urine

Question 17

describe epithelial serous membranes

Answer 17

• composed of a secretory epithelial layer (serous fluid) and a connective tissue layer underneath
• Lines internal body cavities (abdominal and thoracic)

*Associated with simple squamous

Makes serious fluid, provides lubrication for the organs inside of the civity

*visceral means surounding organ itself, parietal means it surrounds the cavity it is in

Question 18

describe glandular epithelia

Answer 18

• gland = one or more cells that makes and secretes particular product
• two key ways to classify this gland:
  1. Site of product release (endocrine or exocrine)
  2. Number of cells forming the gland: unicellular or multicellular (most are multi)

*some unicellular glands are along digestive tract mucosa and in brain (diffuse endocrine system)

-secretions include aa, proteins, glycopeprides, steroids

*ductless glands secret directly into blood stream or extracellular space

Question 19

exocrine glands

Answer 19

• more numerous than endocrine
• secrete products onto body surfaces (skin) or into body cavities
• ex: mucous, sweat, oil and salivary glands, the liver (secretes bile) nd pancrease (secretes digestive enzymes)

Question 20

what is goblet cells an example of

Answer 20

unicellular exocrine glands

• Found in simple columnar and simple cuboidal layers

found in epithelial linings of intestine and resp tract amid columnar cells

• These cells have a lot of golgi and ER, produce a ton of mucin which forms muscus in water

*mucin is secreted into lumen

Question 21

what are the two features of multicellualr exocrine glands?

Answer 21

1. epithelium derives duct
2. secretory unit (acinus) consisting of secretory cells
   - most have supportive connective tissue surrounding the secretory unit, blood vessels and nerve fibers
   - components form a fibrous capsule

Question 22

how can you classify Multicellular exocrine glands?

Answer 22

1. Duct structure: simple (unbranched) or compound (branched)
2. secretory unit structure: tubular (tubes), alveolar (flask like) or tubuloalveolar

Question 23

what are the modes of secretion

Answer 23

Merocrine: products are secreted by exocytosis (pancrease, sweat, salivary)

*vesicels produced in cells, fuse w/ membrane and then out to lumen

Holocrine: products are secreted by the rupture of gland cells (proliferation at bottom, produces new cells and oil cells move up

ex: Sebaceous oil glands of skin (only real example)

Question 24

what is connective tissue? what are the main classes?

Answer 24

• Found throughout the body; most abundant and widely dsitributed in primary tissues
• amount in each tissue varies (skin is primarily connective, brain has very little)

Main classes: connective tissue proper, cartilage, bone, blood

Question 25

What are the functions of Connective Tissue

Answer 25

binding and support protection insulation (fat) transportation (blood

Question 26

what are the common characteristics of connecitve tissue?

Answer 26

1. Common origin: all arise from mesenchyme 2. degrees of vasculatory: cartilage is avascular, dense connective tissue is poorly vascular and others rich is ascularity 3. Extracellular matrix: connective tissue is largely non living extracellular matrix

Question 27

what is ground substance

Answer 27

- functions as a **molecular sieve** through which nutrients diffuse between blood capillaries and cells \*usually not visible on slides becuase it is removed during the preparation process composed of: **Interstitual (tissue) fluid, cell adhesion proteins** (**fibronectin** and **laminin**, serve mainly as connective tissue glue for cell attachment), **proteoglycans**

Question 28

what is the structure of proteoglycans in the Ground Substance?

Answer 28

- proteoglycans = group of glycotroteins that consist of **glycosaminoglycans (GAGs)** **- control ECM volume:** net (-) change attracts H2O directly and indirectly attracts cations 9esp Na+) - Hyalauronic acid acts as a core strucutre for aggretion of proteoglycans \*depending on the combo of GAG attached to link protein, will give rise to different kinda of proteoglycan structure

Question 29

What are the different categories of proteoglycans

Answer 29

\*categorised dependng on the nature of their GAG chains - Chondroitin sulfate and dermatan sulfate heparin and heparan sulfate keratan sulfate

Question 30

what are the different fibers of connective tissue

Answer 30

\* fibers procide support 1. Collagen: fibers cross link providing strength and resist longitudinal stress (Stronger than steel) 2. Elastic: elastic tissue such as skin, lungs and blood vessels (rubberlike protien **elastin)** 3. Reticular: short fine, branched collagenous fibers (collagen type 3) that form delicate netowrks that surround small blood vessels and suport soft tissue of organs

Question 31

Cell types of connective tissue

Answer 31

\* connective tissue has both undifferentiated cells with suffix blast and matuer cells with suffic cyte Primary blast cells * Fibroblasts: connective tissue proper * Chrondroblasts: cartilage * Osteoblasts: bone * Hematopoietic stem cells: blood Other types of cells include: cells, WBC, plasma cells, macrophages and mast cells

Question 32

What are the types of Connective tissue proper

Answer 32

Loose connective tissue: areolar, adipose and reticular Dense connective tissues: dense regular and dense irregular)

Question 33

describe areolar connective tissue proper

Answer 33

- type of loose connective tissue - most widlet distributed in body - serves as a universal packing material (wraps and sushions organs, macrophages phagocytise bacteria) - high content of hyaluronic acid makes the ground substance quite viscous - **Reservoir of water and salts** (nearly as much fluid as in entire bloodstream)

Question 34

adipose (fat) connective tissue

Answer 34

- type of loose connective tissue - adipocytes account for 90% of tissue's mass (not a lot of connective tissue actually assocaited, mainly flat globules) - triglyceride oil droplets occupy most of a fats cell's volume and displaces the nucleus to one side - the **matrix** is scanty and cells packed closely together - **brown at asipose cells** contain adundant mitochondria, which use the lipid fuels to heat the bloodstream to warm

Question 35

describe reticular connective tissue

Answer 35

- a loose connective tissue - the ONLY fibers in the matrix of reticular connective tissue and **reticular fibers** (no collegen or elastic) - forms a delicate network along which fibroblasts called **reticular cells** lie scattered \*network of fibers can support free blood cells in lymph nodes, spleen and bone marrow

Question 36

describe dense regular connective tissue proper

Answer 36

- poorly vascularized and closely packed bundles of collagen fibers running in parallel to **direction of pull** **\***only resists in one direction - provides great resistance to **tension** (pulling forces) - **ligaments** contain more elastic fibers than **tendons** and are slightly more stretchy - it also forms **fascia** (fibroud membrane that wraps around **muscles, blood vessels and nerves)** \*plasic wrap esc - can be referred to as **elastic connective tissue**

Question 37

describe dense irregular connective tissue proper

Answer 37

- similar elements as regular variety - Bundles of collagen fibers are **much thicker** and are arranged irregularly - found where tension is exerted from many different dierctions (ex leathery dermis) - forms fibrous **joint capsules** and fibrous coverings that surround **some organs** (kidneys, bones, cartilages, muscles and nerves)

Question 38

what are the characteristics of Cartilage

Answer 38

- lacks nerve fibers and is **avascular** - receives nutrients by diffusion from blood vessels in the connective tissue membrane (**perichondrium**) - large amounts of GAGs, **chrondroitin sulfate** and **hyaluronic acid** , firmly bound to collegan/elastic fibers - matrix contains large amount of water (~80%) - The **movement of tissue fluid** in its matrix enables: cartilage to rebound after being compressed, helps to nourish the cartilage cells \*when compressed will squeeze out fluid, then as relaxes it refills with fluid

Question 39

what are the types of cartilage

Answer 39

hyaline cartilage: connection of ribs to sternum (costal cartilage), articular cartilage (coverings of longbones), trachea, larnyx, in nose elastic cartilage: two primary sites - external ear and epiglotis fibrocartilage: very dense and can resist pressure - bones of legs (meniscus), public symphysis, intervertebral disk

Question 40

describe hyaline cartilage

Answer 40

- provides firm support with some pliability for the **nose**, **connects the ribs to the sternum**, and supports most of the **respiratory system** - The **embryonic skeleton** is formed of hyaline cartilage - Skeletal hyaline cartilage persists during childhood as **epiphyseal plates** (allow bones to keep growing) - it covers ends of long bones as **articular cartilage** providing springy pads that absorb compression at joints - chondroblasts product the matrix and when mature (chondrocytes) lie in lacunae (easy way to identify this tisssue)

Question 42

describe elastic cartilage

Answer 42

- nearly identical to hyaline cartilage except there is more **elastin fibers** - found where strength and exceptional **stretch ability** needed - part of external ear and epiglottis \*Perichondrium is not cartilage but its connective tissue surrounding it (highly vascular to support avascular cartilage)

Question 43

describe fibrocartilage

Answer 43

- intermediate between hyaline cartilage and **dense regular connective** tissues \*has a lot of collagen - rows of **chondrycytes** alternate with rows of thick collagen fibers - compressible and resists tension and is found where strong support and ability to **withstand heavy pressue** - found in: **inervertebral discs, pubic symphysis** and spongy cartilages of knee (menisci) \*\*look for lacuna in slide

Question 44

describe bone (osseous) tissue

Answer 44

- v good abaility to support, protect structures and provide cavities for fat storage and synthesis of blood cells - **Bone matrix** has collagen fibers and inorganic Ca2+ (bone salts) - **Osteoblasts** produce the organic protion of the matrix: then bone salts are deposited on and in between the fibers

Question 45

Question 46

describe blood tissue

Answer 46

- classified as connective tissue because it developes from **mesenchyme** - RBC and WBC (neutrophils, lymphocytes, monocytes, eosinophils, basophils - Fibers are soluble protein molecules that precipitate, forming large visible fiberlike structures duing blood clotting

Question 47

Question 48

describe nervous tissue

Answer 48

- main component of the nervous system - two major cell types **neurons:** generate and conduct nerve impulses and typically they are branching cells with cytoplasmic extensions or processes **supporting cells**: nonconducting cells that support, insulate and protect

Question 49

Skeletal muscle tissue

Answer 49

- long, cylindical, multinucleate cells: obvious striations functoin: voluntary movment, locomotion, maniputation of env, facial expression, voluntary contral - location: attaches to bones or ocasionally skin

Question 50

describe cardiac muscle tissue

Answer 50

- branching, striated, generally uninucleate cells that interdigitate at specialzed junctions \*as it contracts it propels blood into circulation ON SLIDE: More white space -Filled with adipose tissue to provide energy to cardiac cells Fibers have striations may think skeletal BUT look at darker stained lined going through it (up and down) Intercalating disks Cells also only have one nucleus

Question 52

what are the 3 defenses at bodies external boudnires, what happens if something surpasses them

Answer 52

1. Mechanical barriers: skin and mucosae 2. cilia of epithelial cells lining resp tract 3. strong acid - penetration of barrier stim bodys inflammatory and immune responses **inflammatroy:** non specific and quick **Immune:** v specific and longer to action

Question 53

describe step 1 of tissue repair

Answer 53

1. inflammation - clotting occurs - surface dried and scab is formed - severed blood vesseles bleed and inflammatory chem are released - local blood vessels become more permeable allowing WBC, fluid, clotting factors and other plasma proteins to seep into injured areas

Question 54

describe step 2 of tissue repair

Answer 54

2. restoration of blood supply - clot if replaced by **granulation tissue** which resotres vascular supply \*granualtion tissue is similar to connective but is more dense, gives scar white appearance) **-fibroblasts** product collagen fibers to bidge the gap **- Macrophages** phagocytize cell debris - surface epithelial cells multiply and migrate over the granulation tissue

Question 55

describe step 3 os tissue repair

Answer 55

3. permanet repair - regeneration and fibrosis effect permanent repair - the fibrosed area matures and contracts: the epithelium thickens - fully regenreated epithelium with underlying area of scar tissue results Conrtaction can bring together the tissue areas to remove excess fluid