Topic 2 & 3: Integumentary and Embryology

scientific name of skin

L. integumentum

T or F: skin is one of the best skin indicators of general wealth

True

Functions of the skin

• Protection of the body from env effects (eg., abrasion, fluid loss, harmful substances, UV radiation, and invading microorganisms)

• Containment for the body’s structures and vital substances

• Thermal regulation

• Sensation by way of superficial nerves

• Synthesis and storage of Vitamin D

Layers of the skin

1. EPIDERMIS

● Stratified squamous epithelium

2. DERMIS

● Dense connective tissue

● Blood vessels, lymphatics, and nerves

3. HYPODERMIS

● Fatty layer

● Thermoregulation

● Energy storage

Epidermis

Keratinized epithelium

● Superficial layer that provides a protective outer

surface

● No blood vessels or lymphatics

● IMPORTANT: avascular epidermis is nourished by the

underlying vascularized dermis

What are the cells present in the epidermal layer?

a. Melanocytes

b. Langerhans cells

c. Lymphocytes

d. Merkel cells

Pigment-forming cells from the embryonic neural crest

Melanocytes

Immature antigen-presenting dendritic cells derived from bone marrow

Langerhans cells

Determine immune response to infectious microorganisms and other foreign substances

Lymphocytes

Sensory mechanoreceptors; associated with nerve endings

Merkel cells

Epidermal layers

1. Stratum corneum

2. Stratum lucidum

3. Stratum granulosum

4. Stratum spinosum

5. Stratum basale

Dermis is dense layer of interlacing

collagen and elastic fibers

Dermis is supplied by ________ that enter its deep surface to form

a __________ of anastomosing arteries

arteries , cutaneous plexus

The layer that provides skin tone

dermis

What type of collagen is mainly in adults?

types I and III

The layer that provides strength and toughness of the skin

dermis

another name for tension lines

cleavage lines or langer lines

Tension liens are spiral _________ in the limbs and run _________ in

the neck and trunk

longitudinally, transversely

Tension lines at the ______, ______, _________, and _______ are parallel to the transverse creases that appear when the limbs are flexed.

elbows, knees, ankles, and wrists

Damage to the collagen fibers in the dermis and usually Seen in the abdomen, buttocks, thighs, and breasts during pregnancy

Striae gravidarum

Occur along with distension and loosening of the deep fascia due to protein breakdown leading to reduced cohesion between the collagen fibers

Striae cutis distensae

Seen in obese individuals and in certain diseases like hypercortisolism or Cushing

syndrome

Striae cutis distensae

What are the epidermal appendages

Nails

Hair

Hair foillicles

Arrector pili muscle (musculu arrector pili)

Sebaceous glands

invaginations of epidermis into dermis

hair

Keratinized plates

Nails

what are the Pilosebaceous unit?

● Hair

● Arrector pili muscle

● Sebaceous gland

● Apocrine gland

Skin that lack hair follicles wherein ducts open instead directly on to the skin surface

○ Lips and corners of the mouth

○ Buccal mucosa

○ Nipples (Montgomery’s glands)

○ Areolae of the female breast

○ Penis

○ Inner surface of the prepuce

○ Clitoris and labia minora

○ Meibomian glands

○ Ceruminous glands

Sebaceous glands release sebum into the canal by

holocrine mechanism

Cluster of secretory acini, which open by a short common duct into the dermal piliary canal of the hair follicle

sebaceous glands

Sweat gland is derived from

ectoderm

Long spiral tubular glands

sweat gland

Sweat gland is what type of gland

exocrine (make and release)

Sweat glands are distributed over surface of the body, except at:

Red margins on lips, nail beds, glans penis, & clitoris

What is the most deeply penetrating structures of dermal appendages

sweat gland

Eccrine sweat glands: present in greatest numbers on the ______, _______, _______, and ____ for thermoregulation

palms, soles, axillae, and forehead

Apocrine gland starts functioning at what stage?

puberty

Apocrine sweat glands are only present at

axilla, anus, areola, eyelid and external auditory canal

Richly vascularized loose connective tissue

superficial fascia/ Subcutaneous tissue / hypodermis

Provides for most of the body’s fat storage

superficial fascia

Superficial fascia’s different sites in the same individual

Females: breasts and thighs

Males: lower abdominal wall (beer belly)

Length and density of these ligaments determines mobility of the skin over deep structures

SKIN LIGAMENTS (RETINACULA CUTIS)

A disruption of the continuity of tissues produced by an external mechanical force, a cut or break in the continuity of any tissue, caused by an injury or operation

wound

Caused by a sharp pointed tool, wood splinters, pins, nails, glass, scissors or knives and usually, misleadingly, seems to be negligible.

Puncture wound

involves a linear cut in the skin, which is usually superficial, but may involve deep structures (surgical incisions)

Incised Wound

Cut Wound is similar to an incision, but with an additional

direct perpendicular force

a would that should not be sutured

bite wound

Bite wound is also what type of wound

puncture wound

Area of hemorrhage beneath the skin that is generally due to blunt trauma

Bruise/hematoma

Blunt trauma causes capillaries to

break and leak

Avulsion involves the ____ of tissue

loss

Partial or complete tearing away of skin and tissue beneath

avulsion

abrasion is ______ and usually forms a _____

superficial, scab

Wound type- Avulsion (tissue loss)

Tissue shape- crescent

Orientation- Oblique

Size – 4-5 cm

Anatomical position - Frontal aspect of the forehead

Laterality: Right

Wound type- Abrasion

Shape - Confluent

Orientation- Vertical

Anatomical position- Anterior lateral

The wrapping, packing, and insulating materials of the deep structures of the body

fascias

Covers most of the body parallel to (deep to) the skin and subcutaneous tissue

Deep Fascia

The fascia that is devuod of fat

deep fascia

Investing fascia: extensions from its internal surface invest deeper

structures, such as

individual muscles and neurovascular bundles

Investing fascia are groups of muscles with similar functions sharing the

same nerve supply are located in

fascial compartments

investing fascia are separated by thick sheets of deep fascia, called

intermuscular septa

If the fascia is between the muscles =

intermuscular septa

Fascia groups the muscles into ____________, such as the

muscles in the____ and the ____ which have different functions (and they are covered by the investing fascia)

fascial compartments, arm, leg

In a foot injury where there is an abscess, assessing and treating all sides is important to prevent infections due to

(investing) fascial compartments

When you put together deep fascia + contracting muscles + venous valves, they work together as _____________ to return blood to the heart

musculovenous pump

For the hands, thickened deep fascia forms

retinaculum

hold tendons in place when they cross the joint during flexion and extension

retinaculum

Closed sacs or envelopes of serous membrane, a delicate connective tissue membrane capable of secreting fluid to lubricate a smooth internal surface

bursae

bursae adjacent to viscus/viscera

Visceral layer (inner)

bursae in contact with body wall

Parietal layer (outer)

Intraperitoneal organs examples

stomach, liver, spleen

Enveloped by visceral peritoneum, which covers the organ both anteriorly and posteriorly

Intraperitoneal organs

Covered in parietal peritoneum, which only covers their anterior surface

Retroperitoneal Organs

__________ developed and remain outside of the parietal peritoneum

● Examples include _______, _________, and _______

Primarily retroperitoneal organs

esophagus, rectum, kidneys

Secondarily retroperitoneal organs, through the course of embryogenesis, they

became retroperitoneal as their _________ fused with the ___________

mesentery, posterior abdominal wall

Type of retoreperitoneal organs wherein their only their anterior surface is covered with peritoneum

secondarily retroperitoneal organs

Examples of secondarily retroperitoneal organs

ascending and descending colon

Retroperitoneal Abdominal Viscera

S – suprarenal (adrenal) glands

A – aorta/IVC

D – duodenum (except the proximal 2 cm/ duodenal cap/

first part)

P – pancreas (except the tail)

U – ureters

C – colon (ascending and descending parts)

K – kidneys

E – esophagus

R – rectum

Stages of development of the embryo

• Prenatal period: before birth

  • 38 weeks from conception to birth

  • 40 weeks gestational age (gynaecologic timing base on LMP)

• Embryonic period: first 8 weeks

  • All major organs formed

• Fetal period: last 30 weeks

  • Organs develop and become more complex

Central feature of reproduction is the fusion of the ____________ at fertilization

2 gamete pronuclei

At what phase is the secondary oocyte arrested in a cyclical fashion?

Metaphase of meiosis II

Fertilization occurs in ______________ within ___________

ampullary region of uterine/fallopian tube within 24 hours of ovulation

During sperm binding, interaction between sperm ___________ and __________ in _________ → triggers acrosome reaction

glycosyltransferases, ZP3 receptors, zona pellucida

fusion of outer acrosomal membrane and sperm cell membrane

acrosome reaction

penetration of zona pellucida: aided by

acrosin

The embryo develops a distinct human appearance by the end of what week of embryonic development?

8 weeks

a solid cluster of 12–16 blastomeres

blastula

What happens to the morula after 3 days post fertilization?

reaches the uterus

repeated cleavage of fertilized egg:

morula → blastula → early gastrula → gastrula

In blastocyst formation, what becomes the embryo in the inner cell mass?

embryoblast

In blastocyst formation, what becomes the fetal portion of placenta in the outer cell mass?

trophoblast

During implantation or post fertilization: blastocysts implant within the __________ wall of the uterus

posterior superior

After 2 weeks, the Embryoblast differentiates into 2 cellular layers:

● Epiblast → clefts develop and eventually coalesce to form the amniotic cavity

● Hypoblast → line inner surface of cytotrophoblast to form exocoelomic membrane which delimits the primitive yolk sac

Trophoblast further develop into:

● Syncytiotrophoblast→ form lacunar network thru which maternal blood flows--> establishing uteroplacental circulation

● Cytotrophoblast→ produce local mounds called primary chorionic villi bulging into syncytiotrophoblast

Development of extraembryonic mesoderm wherein it consists of somatic mesoderm, cytotrophoblast and syncytiotrophoblast

Chorion

Human chorionic gonadotropin (hCG) is a glycoprotein produced by the

syncytiotrophoblast

What Stimulates production of progesterone by the corpus luteum, which is essential for maintenance of pregnancy

Human chorionic gonadotropin (hCG)

Until what week hCG is necessary for maintenance of pregnancy?

8 weeks

On what days of missed menses is more reliable for pregnancy to be confirmed

8 or 10 days of missed menses

What takes over hCG for progesterone production for pregnancy maintenance?

placenta

How long is embryonic period?

Weeks 3-8