Common integument

Question 1

What are the main layers of the common integument?

Answer 1

The common integument consists of the subcutis (hypodermis), dermis, and epidermis. It also includes modified structures such as hair, glands, footpads, claws/hooves, and horns.

Question 2

What is the subcutis and what is its function?

Answer 2

The subcutis is loose connective tissue between the skin and muscle fascia, containing adipose tissue for insulation, energy storage, and cushioning.

Question 3

What is the dermis composed of?

Answer 3

Mainly connective tissue containing collagen (types I & III), elastin, blood and lymphatic vessels, nerves, sensory receptors, hair follicles, glands, and arrector pili muscles.

Question 4

What are the layers of the epidermis?

Answer 4

From deep to superficial: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum (in thick skin), and stratum corneum.

Question 5

Which cell types are found in the epidermis?

Answer 5

Keratinocytes (most abundant), melanocytes (pigment), and Langerhans cells (immune function).

Question 6

What are cutaneous muscles and where are they found?

Answer 6

Thin sheets of muscle in the subcutis that move the skin (e.g., platysma, cutaneous trunci, cutaneous omobrachialis). They help flick skin to remove insects.

Question 7

How is the epidermis nourished if it lacks blood vessels?

Answer 7

Through diffusion from the dermis below.

Question 8

Describe the blood supply to the dermis.

Answer 8

Three vascular plexuses: subcutaneous plexus → reticular vascular plexus (deep) → superficial papillary plexus (capillaries branch from here).

Question 9

What is the significance of the vascular plexuses in surgery?

Answer 9

Knowledge of these plexuses is crucial for designing skin flaps and grafts that maintain adequate blood supply.

Question 10

How does the skin regulate blood flow?

Answer 10

Arterioles and venules can dilate or constrict to control blood flow, aiding thermoregulation.

Question 11

What types of nerves innervate the skin?

Answer 11

Sensory nerves (detect pressure, pain, heat) and autonomic nerves (control glands, arrector pili muscles, and blood vessels).

Question 12

Where do cutaneous nerves arise from?

Answer 12

They branch from spinal nerves at regular intervals along the body, each supplying a specific skin region.

Question 13

Why is knowledge of cutaneous nerve distribution important?

Answer 13

It is essential for performing local anaesthesia and identifying spinal lesions.

Question 14

What are corpuscles in the dermis?

Answer 14

Encapsulated sensory nerve endings that detect pressure or vibration (e.g., Pacinian corpuscles).

Question 15

List the main functions of the common integument.

Answer 15

Protection, immune defence, environmental sensing, thermoregulation, storage and excretion, communication/camouflage, and selective permeability.

Question 16

How does the skin provide protection?

Answer 16

Through keratinised layers, collagen, fat, and pigmentation(against radiation), as well as epidermal organs like claws and horns.

Question 17

How does the integument contribute to immune defence?

Answer 17

It forms a physical barrier, contains immune cells like Langerhans cells, and produces antimicrobial secretions.

Question 18

How does the skin contribute to thermoregulation?

Answer 18

Via sweating, piloerection, control of blood flow, and insulation by subcutaneous fat.

Question 19

How is the integument involved in communication?

Answer 19

Through pigmentation, glandular secretions, raising hair or feathers, and epidermal structures used for display.

Question 20

What is meant by selective permeability of the skin?

Answer 20

The skin is mostly waterproof due to keratin and oils but allows limited absorption of some drugs; some animals can respire through skin.