11. 9 skin

Question 1

skin functions

Answer 1

thermoregulation, protection, gives sensory input, excretion, blood reservoic and makes vit D

Question 2

thermoregulation

Answer 2

Blood can be shunted away capillaries of skin
to reduce heat loss. Hairs can be erected (piloerection) via sympathetic stimulation to trap
insulating air next to skin.

Note that ‘goosebumps’ (piloerection reflex) can occur when cold
or in response to stress/emotion (fxn in human ancestors [vestigial reflex] may have been to
make them appear larger to scare off predators.

Question 3

Immunity: through skin

Answer 3

specialized cells of the epidermis are components of immune system

Question 4

Blood reservoir: skin

Answer 4

Vessels in the dermis hold up to 10% of the blood in resting adult

Question 5

Vit D synthesis: skin

Answer 5

UV radiation activates skin molecule that is a precursor to Vit D

Question 6

epidermis layers

Answer 6

corneum, lucidum, granulosum, spinosum, basale

top—-> bottom
COME LET’s GET SUN BURNED

Question 7

Stratum corneum

Answer 7

25-30 dead layers (variable thickness); filled w/ keratin and
surrounded by lipids
i. Lamellar granulues make it water repellent

Question 8

Stratum lucidum –

Answer 8

only in palms and soles of feet, and finger tips; 3-5 layers, clear/ DEAD

Question 9

Stratum granulosum

Answer 9

3-5 layer of dying cells; lamellar bodies release hydrophobic lipids HERE

Question 10

Stratum spinosum

Answer 10

strength and flexibility; 8-10 layers held together by (desmosomes-keratin involving adhesion proteins)
- also have Langerhans cells here

Question 11

Stratum basale

Answer 11

(germinativum) – deepest layer. contains Merkel cells and stem
cells that divide to produce keratinocytes; attached by basement membrane. Melanocytes are found here.
** rapid division of cells

Question 12

Keratinocytes:

Answer 12

produce the protein keratin that helps waterproof the skin. As they
are pushed up to top layer of skin they accumulate keratin and die, losing their
organelles along the way. Keratin is most abundant protein in epidermis.

Question 13

Melanocytes:

Answer 13

transfer skin pigment melanin to keratinocytes

Question 14

3. Langerhans cells:

Answer 14

interact with helper T-cells of immune system

Question 15

Merkel cells:

Answer 15

attach to sensory neurons and fxn in touch sensation

Question 16

Dermis

Answer 16

primarily connective tissue; collagen and elastic fibers; contains hair follicles,
glands, nerves, and blood vessels. Tightly connected to the epidermis above via basementmembrane. Highly vascularized.

*has two layers, papillary region and reticular region

Question 17

Papillary region of dermis

Answer 17

thin vascular network within upward projecting papillae
helps supply nutrients to epidermis + regulate temp. Papillae also contain
Meissner’s corpuscles (sensory touch receptor) and their upward projection is what
creates fingerprint ridges (not to be mixed up w/ tongue papillae that have taste
buds on their surface).

Question 18

Reticular region of dermis

Answer 18

dense connective tissue, collagen and elastic fibers; packed with oil glands, sweat gland ducts, fat, and hair follicles; provides strength, and elasticity (stretch marks are dermal tears)

Question 19

dermal chromatophores.

Answer 19

camoflage cells

Question 20

Hypodermis (subcutaneous)

Answer 20

technically not part of skin (but is part of the integumentary
system); areolar and adipose tissue; fat storage (heat insulator); pressure sensing nerve endings; passage for blood vessels; shock absorber

Question 21

Sebaceous (oil) glands

Answer 21

– connected to hair follicles; absent in palms and soles. Secretes oil
(sebum) that keeps skin relatively acidic to discourage microbial growth. Acne is caused by these
glands getting plugged.

Question 22

Sudoriferous (sweat) glands

Answer 22

eccrine or apocrine

Question 23

eccrine sweat gland

Answer 23

(most of the body)- regulate temperature through perspiration; eliminate urea.
Open directly to skin.

Question 24

apocrine sweat gland

Answer 24

– armpits, pubic region, and nipples; secretions are more viscous. Open to hair
follicles.

Question 25

Ceruminous (wax) glands

Answer 25

– found in ear canal; produce wax-like material as barrier to entrance

Question 26

what stands hair up on arms

Answer 26

smooth muscle

Question 27

burn degrees

Answer 27

1st (epithelial layer), 2nd (epithelial + part of dermal), 3rd (both skin layers + extends into
subcutaneous)

Question 28

what skin layer to reptiles molt

Answer 28

corneum

Question 29

what are the tissues in plants

Answer 29

EM Video Games

- epidermis, meristem, vascular, ground