Question

Use the figure to match the following: 31) Hypodermis 32)--Epidermis 33) Reticular layer of the dermis 34)Papillary layer of the dermis 35) When an individual is exposed to extremely cold air the dermal blood vessels will dilate so that more blood will be brought closer to the outside surface of the skin. A) True B) False 36) Place the following events in the order in which they occur during sound transmission: 1. Tympanic membrane vibrates 2. Internal ear fluids are set in motion 3. Hearing receptors are stimulated 4. Ossicles of the ear vibrate 5. Auditory cortex is stimulated A) 2,1,5,3,4 B) 5,1,2,4,3 C) 1,4,2,3,5 D) 1,2,4,3,5

Answer 1

Match the following:

D : Hypodermis

A : Epidermis

C : Reticular layer

B : Papillary layer

Structure of the skin:

Epidermis: it is the top layer of skin.It consists of an intact arrangement of epithelial cells called keratinocytes(since they can produce a protein called keratin).

It is composed of four layers primarily which are,

Stratum basale- the bottom-most single layer of cells interspersed with non-keratinocytes like melanocytes(pigment producing) cells and touch receptors called Merkel's cells along with regular keratinocytes

Stratum spinosum - Also known as the prickle cell layer due to its spiny appearance.The cells are attached to each other by desmosomes.The Langerhans cells are present between them which are immune cells helping in foreign body phagocytosis.

Stratum granulosum - Consists of cells containing granules of keratohyalin( a protein).

Stratum corneum - There are no cells in this layer. It is made of sheets of flattened protein. It is the superficial layer which is exposed to outside environment and offers mechanical protection.

At certain places, an additional layer called stratum lucidum is also present which is composed of homogeneous cells with distinct boundaries.

Dermis: The middle layer present between the epidermis and the hypodermis.It is also called the connective tissue layer and is vascular compared to the epidermis.It consists of blood vessels, lymph vessels, nerves, sweat and sebaceous glands and hair follicles. It is separated from the epidermis above by a basement membrane.The dermis is of two types;

Papillary dermis: This is the top layer of the dermis which is projected into the stratum basale of the epidermis forming finger-like projections.

Reticular layer: Forms the main bulk of the connective tissue made of collagen and elastin fibers.It contains a rich network of sensory nerves.

Hypodermis: Found below the dermis layer and it called the superficial fascia.It is majorly made of fat and hence provides a cushioning effect and also insulation. Its function is to connect the dermis to underlying bone or muscle.

Q35.Answer is false

Our normal core body temperature is 37 degree celsius. When the skin is exposed to extreme cold, to maintain a stable inner(core) temperature, the blood vessels in the dermis will constrict so that less blood will flow to the area and likewise when exposed to heat, to dissipate excess heat, the blood vessels dilate so that more blood will reach the surface giving off the heat. Both these mechanisms are to maintain a stable core body temperature.