Integumentary System

Question 1

What are the functions of skin?

Answer 1

Protection
Regulation
Excretion
Perception
Storage

Question 2

What does the skin provide protection from?

Answer 2

Mechanical damage
Chemical damage
Bacterial damage 
Thermal damage 
UV radiation
Desiccation

Question 3

How does skin protect from Desiccation?

Answer 3

(pathogen invasion)

keratinised layer becomes thickened where necessary

Question 4

How does skin protect from Ionising radiation?

Answer 4

Menalin produced by melanocytes (in the epidermis) which penetrates surrounding cells and absorbs UV light

Question 5

How does skin protect from Predation?

Answer 5

Hair and skin pigment acts as camouflage
hair or fur is raised in aggression
claws nails and horns to attack

Question 6

What is the function of the integumentary system?

Answer 6

Food Storage- accumulation of subcutaneous fat

Production of Vitamin D which is important for bone formation, neuromuscular function and cell regeneration

Question 7

What is skin colour determined by?

Answer 7

Melanin- yellow brown of black
Carotene- orange pigment from veg
Haemoglobin- red colouring from RBC’S

Question 8

What are the layers of skin

Answer 8

Epidermis- stratified squamous epithelium that withstands wear and tear
Dermis- thicker than epidermis
Hypodermis- anchors skin to organs

Question 9

What is the Epidermis made up of?

Answer 9

Stratum Corneum- outermost layer (tough and dry with old and dead cells)

Stratum Basale- innermost layer which forms the germinal layer and is in constant mitotic division. The cells move towards the surface and may produce keratin

Question 10

What is the Dermis made up of?

Answer 10

Fibrous protein network- contains collagen and elastin
Blood vessels- nourish and heat transfer
Sensory nerve endings- touch, pressure and temperature changes
Lymphatics
Bone-may form in the dermis

Question 11

What are the layers of the Dermis?

Answer 11

Papillary layer 1/5 of dermis- connective tissue and elastic fibres with projections called dermal papillae (pain receptors- nociceptors)
Reticular layer 4/5 of dermis- dense and irregular connective tissue, collagen and elastin. Contains blood vessels, glands, nerve receptors and adipose tissue

Question 12

What is the Hypodermis?

Answer 12

layer of loose connective tissue that separates dermis from organs.
allows skin movement without tearing
contains adipose tissue for storage, padding and acts as a thermal insulator.

Question 13

What are the four mechanoreceptors that are sensitive to external stimuli?

Answer 13

1.Meissner’s corpuscles (light touch)
encapsulated nerve endings encased by
stacked flattened discs just below epidermis
▪ esp. on fingertips, lips, nose, forehead (humans)
▪ least on soles of feet
2. Pacinian corpuscles (vibration and pressure)
Onion-like capsule located deep in the skin
3. Ruffini corpuscle (temperature, stretch, movement)
Branched fibres inside a cylindrical capsule
4. Merkel nerve endings (pressure and form)
Disc-shaped receptor near the border of epidermis and dermis

Question 14

How does the skin regulate temperature?

Answer 14

homeotherms

cooling by the exocrine sudoriferous (sweat glands)
deep epidermal in-folding into the dermis
open to outer surface or into fair follicles
found over entire body surface

increase heat loss by vasodilation and relaxation of Arrector pili muscles

reduce heat loss by vasoconstriction and contraction of arrestor pili (also insulating fat and insulating fur)

Question 15

What is the skin gland, Sudoriferous glands?

Answer 15

sweat gland 
mainly h2o k and NaCl
horses sweat readily (latherin)
pigs don't sweat
secretions may contain pheromones

Question 16

What is the skin gland, Sebaceous glands?

Answer 16

produce oily sebum which keeps the skin water resistant
arrestor pili contractions compress glands
empty into the hair follicle

Marking glands

• sheep- infraorbital, interdigital
• goats- horn glands
• pigs- carpal glands

Question 17

What are the three types of skin glands ?

Answer 17

Merocrine (Eccrine)- exocytosis to pore- concentrated to soles of feet, palms and forehead- odourless

Apocrine- larger and deeper in skin eg; eyelids, genitals etc- bud secretions via plasma membran- odorous

Holocrine- sebaceous or sudoriferous glands- duct to pore- cell dies- odorous-
parallel to hair follicle before the muscle

Question 18

What are the characteristics of hair?

Answer 18

grows from follicles
angle adjusted by contraction of arrestor muscles- thermoregulatorary function- used during fight or flight- 90 degrees
can be seasonal shedding which is triggered by photoperiod changes

Question 19

What are the three main types of hairs?

Answer 19

Guard hairs- smooth outer coat
Wool hairs- undercoat- fine and curly- contains lanolin oils- produced commercially by sheep etc
Tactile hairs (vibrissae) (whiskers)- long and stiff which are common on the face, around the lips, eyes with special innervations used as probes.

Question 20

What are skin modifications?

Answer 20

hoof, claws, nails
horns and antlers
feathers
scales
dermal bone
perception organs