Tissue, glands, skin, sensory receptors

A tissue sample must allow oxygen to diffuse rapidly between two surfaces. The cells form one thin layer. Which epithelial organization best supports this function

and why?

A tissue lining the digestive tract must absorb nutrients and release mucus. How do epithelial structure and specialized cells support these functions?

Simple columnar epithelium commonly supports absorption and secretion

microvilli increase surface area for absorption

while goblet cells secrete protective and lubricating mucus

A tissue has multiple layers of cells with flattened cells at the exposed surface. Why is this better suited to protection than rapid diffusion?

Stratified squamous epithelium resists abrasion because multiple layers protect underlying cells

superficial cells can be damaged or shed while deeper cells replace them

A student claims all living epithelial tissue has its own blood supply. Correct the claim and explain how epithelial tissue receives nutrients.

Epithelium is avascular

oxygen and nutrients diffuse from blood vessels in the underlying connective tissue across the basement membrane

A person has damage limited to the epidermis. Why can it still receive nutrients

and what could happen if the underlying dermis were severely damaged?

severe dermal damage can disrupt this supply and impair healing

A tissue sample contains cells that secrete mucus and tiny projections that increase surface area. How do these features perform different jobs?

Goblet cells secrete mucus for lubrication and protection

microvilli increase cell-surface area to support absorption

A person's sweat glands cannot release normal secretions. During exercise

body temperature rises. Explain the connection between sweat glands and homeostasis.

evaporation removes heat and helps maintain body temperature

so impaired sweating can contribute to overheating

Two people sweat equally during humid weather

but one remains overheated. Why does sweat production alone not guarantee cooling?

high humidity slows evaporation

so sweat may drip off without providing as much cooling

An injury destroys dermal blood vessels beneath an intact epidermis. Predict two possible consequences.

The epidermis may receive less oxygen and fewer nutrients by diffusion

damage to dermal vessels can also affect heat exchange

A burn damages the epidermis but leaves most of the dermis intact. Why might it heal differently from a deeper burn that destroys dermal structures?

Surviving basal keratinocytes can replace damaged epidermal cells

deeper burns may destroy blood vessels

follicles

A medication prevents keratinocytes from producing adequate keratin. How could this affect the skin's protective role?

The epidermal barrier may become less effective at resisting abrasion and limiting water loss

A person loses much of their ability to detect light touch but can still sweat normally. Which functions are affected differently

and why?

sweat glands can still secrete because sensation and glandular secretion are distinct functions

A person touches a very hot surface and rapidly withdraws their hand. Explain the roles of sensory receptors and the nervous system.

Thermoreceptors or nociceptors detect the stimulus

sensory neurons transmit information to the nervous system

which coordinates a motor response that withdraws the hand

An injury damages pressure and vibration receptors but leaves many pain receptors intact. Predict the sensory changes.

Pressure and vibration detection may be reduced

A person has damage to the papillary dermis but an intact epidermis. Why could sensation and epidermal support be affected?

The papillary dermis contains capillary loops that help nourish the avascular epidermis and contributes to skin's sensory structures

damage may impair sensation and epidermal support

A person has reduced arrector pili muscle activity. What visible response would decrease

and why is this different from sweating?

sweating is produced by glands and is a separate process

A hair is pulled out of its follicle

but the surrounding epidermis remains intact. Why does hair growth depend on a specialized region rather than the visible shaft?

growth occurs in the living hair matrix at the follicle's base

where cells divide and become keratinized

A person has damaged sebaceous glands but functioning eccrine sweat glands. Which skin functions may change

and which may remain intact?

eccrine sweat secretion and evaporative cooling may remain intact

A patient has impaired melanocyte function but normal keratinocytes. Which skin property may change

and why is the barrier not necessarily lost?

normal keratinocytes can still maintain the epidermal barrier

A patient has impaired vitamin D synthesis in the skin. Explain one possible consequence for the skeleton.

Reduced vitamin D can decrease intestinal calcium absorption