Chapter 3 - Tissues

Question 1

what are tissues ?

Answer 1

collections of specialized cells and their extracellular matrix (non-cellular extracellular substance surrounding them) that perform a relatively limited number of function.

Question 2

what are the 4 primary tissues type ?

Answer 2

epithelial, connective, muscle and nervous

Question 3

what is microvilli ?

Answer 3

non-motile projections of the cell membrane (containing microfilaments) on most epithelia

Question 4

what does microvilli do ?

Answer 4

• increase surface area for absorption and secretion

* so dense in the first portion of the kidney tubule known as the “brush border”

Question 5

cilia ?

Answer 5

motile projections on the apical surface of the cells that can sweep substances such as mucus along the tube – e.g. pseudostratified ciliated columnar epithelium of the trachea

Question 6

what is basil lamina ?

Answer 6

o specialized type of extracellular material secreted by epithelial and connective tissue cells (Fig 3.3)
♣ important role in tissue repair

Question 7

what is the function or role of the epithelium ?

Answer 7

• protection of underlying structures
• acting as a barrier – prevents certain substances from crossing, barrier to water and limits water loss from body
• allows passage of certain substances– readily exchanges oxygen and carbon dioxide through lung epithelium and others epithelium are more selective – filtering at the kidney
• secretion – mucus glands, sweat glands, and enzyme-secreting portions of the pancreas are all composed of epithelial cells that secrete their products onto surfaces or into ducts
• absorbing substances – contain specialized carrier proteins on their membranes that allow specific components to be transported – e.g. intestinal epithelium

Question 8

function of connective tissue ?

Answer 8

• enclosing and separating other tissues (packing material)
• connecting tissues to one another – tendons (muscle to bone), ligaments (bone to bone)
• supporting and aiding in the movement of the body – bony skeletal, joints between bones
• energy/nutrient storage – adipose tissue stores fat, bones store minerals
• cushioning and insulating – adipose tissue protects the tissue it surrounds and the insulating layer below the skin conserves heat
• transportation – blood
• protection – lymph with cells of the immune system, bones

Question 9

what causes skin cancer ?

Answer 9

• most result from ultraviolet (UV) light damage
o produces mutations in genes of epidermal cells - if not repaired passed to daughter cells during mitosis
♣ if mutation present in oncogene or tumor suppressor genes – uncontrolled cell division can occur

Question 10

amount of melanin affects likelihood of developing skin cancer –
true or false ?

Answer 10

True

Question 11

the amount of melanin affects the likelihood of developing skin cancer ?
True or false

Answer 11

True.

Question 12

most common area to have skin cancer ?

Answer 12

face, neck, dorsum of forearm and hand

Question 13

amount of melanin affects likelihood of developing skin cancer –
true or false ?

Answer 13

True

Question 14

Risk of having skin cancer increase with …

Answer 14

♣ fair-skinned individuals
♣ longer term or intense exposure to UV
♣ over 50 years of age with repeated recreational or occupational exposure to UV or history of sunburns

Question 15

what are the different type of skin cancer ?

Answer 15

basal cell carcinoma
squamous cell carcinoma
malignant melanoma

Question 16

how to prevent skin cancer ?

Answer 16

limit sun exposure, use of broad-spectrum sunscreen of at least SPF 15

Question 17

skin cancer is also produced by :

Answer 17

• some induced by chemicals, x-rays, depression of immune system, inflammation, genetic predisposition

Question 18

squamous cell carcinoma

Answer 18

• second most common type affecting cells in stratum spinosum
o wart-like growth, persistent scaly red patch, or elevated growth with central depression
o removal or destruction of the tumor cures most cases

Question 19

Appearance of basal cell carcinoma ?

Answer 19

o have varied appearance
♣ open sores that bleed, ooze or crust for several weeks
♣ reddish patches
♣ shiny, pearly or translucent bumps

Question 20

What is basal cell carcinoma ?

Answer 20

• most common type affecting stratum basale

o rarely metastasize - removal or destruction of the tumor cures most cases

Question 21

malignant melanoma

Answer 21

• least common but accounts for most skin cancer related deaths
o most are black or brown due to increased number of melanocytes
o ~ 40% develop in pre-existing moles
o treatment when confined to epidermis almost always successful
o if invades dermis and metastasizes to other parts of the body = very difficult to treat with survival rate <10%
o early detection vital

Question 22

Burns are classified according to …

Answer 22

o	extent (%) of surface area involved 
o	depth of burn

Question 23

burns are …

Answer 23

= injury caused by heat, cold, friction, chemicals, electricity or radiation

Question 24

degrees of depth of burn ?

Answer 24

♣ partial-thickness burn = 1st and 2nd degree burns

♣ full-thickness burn = 3rd degree burns

Question 25

1st degree burn ?

Answer 25

• involves epidermis only o redness, pain, and slight edema o sunburn, brief exposure to hot or cold objects heals in ~1 week without scarring

Question 26

2nd degree burn ?

Answer 26

• 2nd degree burn – involves epidermis and dermis o minimal dermal damage o pain, redness, edema, and blisters o healing in approximately 2 weeks with no scarring – regeneration from epidermis in hair follicle and sweat glands and edges of wound

Question 27

what is classified as a minor burn ?

Answer 27

= 3rd degree over <2%, or 2nd degree of <15% BSA

Question 28

treatment for burns ?

Answer 28

o aseptic environment o antimicrobials o intravenous fluids (to counter loss of fluids from leaky capillaries) o high protein, high-calorie diets (needed due to hypermetabolic state) o debridement (removal of dead tissue from the burn) o skin grafts

Question 29

Frostbite

Answer 29

most common type of freezing injury of skin • occurs when skin temperature drops below 0oC (32oF) and ice crystal formation damages tissues • skin first appears pale – reduced blood flow to conserve body heat, then brief periods of red – increased blood flow due to local dilation of blood vessels, then white = total lack of blood flow to area • as cells die – become necrotic, area can become black and swollen (activation of immune system)

Question 30

Can skin be used as a diagnostic aid ?

Answer 30

yes, • it can reflect events occurring in other parts of the body

Question 31

rashes and lesions cause by ?

Answer 31

o can be manifestations of problems elsewhere ♣ scarlet fever – from bacterial infection of throat – release toxin that produces pink rash ♣ allergic reactions – histamine release producing swelling and redness – hives

Question 32

what is cherry red nails bed or lips ?

Answer 32

carbon monoxide poisoning (not always seen – occurs when haemoglobin binds >25% carbon monoxide

Question 33

what is psoriasis ?

Answer 33

• arises from malfunction of keratinization process o stems cells in stratum basale unusually active • affected areas have red bases and large scales of epidermis that are sloughed off

Question 34

Can skin shows nutritional status ? | if so, example ?

Answer 34

♣ vitamin A deficiency – causes excess keratin production = sandpaper texture to skin ♣ iron deficiency anemia – nails lose normal contour – become flat or concave

Question 35

hair composition changes when ..

Answer 35

o poisonings - heavy metals (lead), arsenic, incorporated in shaft

Question 36

What are merkel cells ?

Answer 36

1. specialized epidermal cells associated with sensory nerve endings o responsible for detecting light touch and superficial pressure

Question 37

during pregnancy or disease state, does it change the person melanin production ?

Answer 37

yes, it changes due to hormones which increases melanin production. o estrogen and melanocyte-stimulating hormone in pregnant females

Question 38

what is albinism ?

Answer 38

o albinism = recessive genetic trait that results in lack of tyrosinase – the enzyme required to make melanin so lack pigment in skin, hair and irises of eyes

Question 39

what is Addison's disease.

Answer 39

o increased adrenocorticotropic hormones

Question 40

dermis is divided into 2 layers ?

Answer 40

papillary layer | reticular layer

Question 41

what type of connective tissue is there in the dermis ?

Answer 41

• collagen is the main connective tissue fiber but also contains elastin and reticular fibers

Question 42

reticular layer

Answer 42

layer = dense irregular connective tissue o main layer of the dermis o continuous with subcutaneous tissue o resists stretching in many directions o orientation of elastin and collagen fibers in some directions more than others

Question 43

subcutaneous tissue

Answer 43

not part of the skin but skin rests on top of it • hypodermis or superficial fascia • loose connective tissue containing fibroblasts, adipocytes and macrophages • supplies blood vessels and nerves to skin • amount of adipose in the subcutaneous layer varies with age, sex and diet o stores approximately half the lipids of the body o insulates body o pads (protects) underlying structures o energy source

Question 44

papillary layer

Answer 44

loose connective tissue with thin fibers o more superficial layer containing dermal papillae – projections that extend toward the epidermis o contains capillaries – smallest blood vessels that supply oxygen and nutrients to the epidermis o lie in parallel curving ridges in the thick skin of the hands and soles of the feet and shape the overlying epidermis ♣ increase friction and improve grip ♣ form unique fingerprints and footprints

Question 45

reticular layer

Answer 45

layer = dense irregular connective tissue o main layer of the dermis o continuous with subcutaneous tissue o resists stretching in many directions o orientation of elastin and collagen fibers in some directions more than others

Question 46

vellus hair are replaced at puberty by terminal hairs in :

Answer 46

o pubic and axillary areas o 90% of chest, arm and leg hairs in males, and 35% in females o males – replacement of face vellus forms beard

Question 47

lanugo

Answer 47

• un-pigmented, delicate hair that appears at 3 months’ gestation covers the fetus at 5-6 months’ gestation

Question 48

information about hair growth

Answer 48

♣ scalp hair grows for 2-5 years ♣ grows approximately 0.3 mm per day ♣ normally lose approximately 50 scalp hairs per day ♣ genetics and testosterone involved in pattern baldness

Question 49

what are the major glands of the skin ?

Answer 49

major glands of the skin = sebaceous and sweat glands

Question 50

hairs has when kind of cycle ?

Answer 50

has growth cycle and resting cycle – new cycle begins and new hair replaces old hair that falls out of the follicle

Question 51

information about hair growth

Answer 51

♣ scalp hair grows for 2-5 years ♣ grows approximately 0.3 mm per day ♣ normally lose approximately 50 scalp hairs per day ♣ genetics and testosterone involved in pattern baldness

Question 52

furuncle

Answer 52

♣ abscess (“boil”) caused by blockage of sebaceous follicle duct • treatment = lancing (cutting) furuncle

Question 53

sebaceous glands

Answer 53

• simple or compound alveolar glands located in the dermis o produce sebum – oily, white substance rich in lipids ♣ halocrine glands - products released by lysis and death of secretory cells ♣ oils hair and skin to prevent drying ♣ protects against some bacteria o connected by duct to upper part of hair follicle

Question 54

sebaceous follicles

Answer 54

large sebaceous glans that communicate directly with the epidermis and do not contain hair

Question 55

Myocytes

Answer 55

(muscle cells) contract, or shorten along longitudinal axis and force produce movement

Question 56

skeletal muscle

Answer 56

muscles attach to bone allowing body to move o myofibers = long, slender, cylindrical, multi-nucleated cells ♣ nuclei located just under the plasma (cell) membrane ♣ sarcoplasm filled with bundles of contractile proteins whose arrangement causes muscle to be striated (contain light and dark bands) o voluntary (conscious) neural control

Question 57

cardiac muscle

Answer 57

``` • found in the heart and is responsible for pumping of blood o cylindrical cells that are branched and shorter than skeletal muscle cells, contain one centrally located nucleus per cell, striated due to the arrangement of contractile proteins o intercalated discs between cells – specialized connections containing gap junctions o involuntary (unconscious) neural control ```

Question 58

smooth muscle

Answer 58

``` • forms walls of hollow organs (except heart), iris of the eye, skin o small spindle-shaped cells with single centrally-located nucleus o arrangement of contractile proteins different from skeletal and cardiac muscle therefore no striations o involuntary (unconscious) neural control ```

Question 59

nervous tissue

Answer 59

• found in brain, spinal cord, and nerves and able to conduct electrical impulses (action potentials)

Question 60

neurons contains

Answer 60

• = conducting cells that contain: o cell body with central nucleus o dendrites – generally short multi-branched projections of the cell membrane that receive the action potentials allowing the impulse to move into the cell body o axon (nerve fiber) –one per cell and is long, thin with a consistent diameter and conducts action potentials away from the cell body • neuroglia = support cells that nourish, protect and insulate neurons

Question 61

tissue membrane

Answer 61

• thin sheet usually composed of a superficial epithelial layer and a connective tissue layer that covers a structure or lines a cavity

Question 62

skin

Answer 62

cutaneous membrane

Question 63

mucous membrane

Answer 63

• epithelial cells and thick layer of loose connective tissue – lamina propria o line cavities and canals that open to the outside ♣ digestive, respiratory, urinary, and reproductive tracts o contain goblet cells or mucous glands that secrete mucus ♣ forms protective barrier that resists entry of pathogens

Question 64

serous membrane

Answer 64

• contains mesothelium – single layer of simple squamous epithelium, a basement membrane, and a delicate layer of loose connective tissue

Question 65

serous membrane , where does it line ?

Answer 65

o do not open to the exterior – line cavities (e.g. pericardial sac)

Question 66

serous membrane , glands

Answer 66

o do not contain glands but mesothelium secretes serous fluid ♣ lubricates membrane and makes it slippery ♣ protects internal organs from friction ♣ acts as selective permeability barrier

Question 67

synovial membrane

Answer 67

• only made of connective tissue that line freely moveable joints o secrete synovial fluid – rich in hyaluronic acid