Integumentary, Circulatory, Immune

Major functions of the skin (4)

Primary defense mechanism against the environment

Plays a role in sensation perception, and helps to regulate body temperature foreign outside invaders

Thermoregulation

Protection

Sensation

Metabolic function 

Three layers of the skin 

Epidermis, Dermis, Subcutis 

Function of the epidermis

Protection from the environment, water retention, immune response, neurosensory

Function of the Dermis and what it consists of

Protection from trauma- elasticity and durability, immune response, thermoregulation, sensory

Dense irregular CT, collagen/elastic fibers, blood vessels, nerves, sensory receptors

Function of the subcutis- what’s another name for it?

Hypodermis- Insulation, reserves energy (fat storage), absorbs trauma 

Differences in papillary and reticular layers of the Dermis

Papillary is the upper region, consists of loose CT

Reticular is the lower region, consists if dense irregular CT

Order of layers of the Epidermis (surface to dermis)

1. Stratum basale (basal layer)

2. Stratum spinosum (prickle cell layer)

3. Stratum granulosum (granular layer)

4. Stratum lucidum (clear layer)

5. Stratum corneum (Keratin layer)

Function of the Stratum Basale, cellular makeup

Deepest layer, sits above the basement membrane 

simple cuboidal or low columnar

Proliferative and repeated miotic division- maintains structure of the epidermis

Function of the stratum spinosum, cellular makeup

Prickle layer- lower layer, keratinocytes, desmosomes  

Cells start to flatten out, 4-6 rows, synthesis precursor for keratinocytes 

Function of the stratum granulosum

Granular layer- upper layer, single or few layers of flattened cells - more flattened the closer to the lucidum (or corneum)

granulates (3-5 layers) keratinization begins here- aids in water retention

Function of the stratum lucidum, cellular makeup

clear layer in thick skin, flattened dead cells

lipid layer, water retention

Function of the stratum corneum

Water retention, shedding of cells

Flat flakes and sheets of nuclei, No nuclei

Thin vs Thick skin tissue

Thick- 5 layers of thick epidermis, thick corneum (keratin, found in palms and soles of feet), lacks hair 

Thin- 4 layers of epidermis- lacks lucidum- thin corneum (keratin), covers most of the body, usually has hair 

Largest organ in the body

Skin

Two systems within the circulatory system

cardiovascular and lymphatic vascular system

Cardiovascular is made up of what? What’s it responsible for?

Heart, blood vessels (arteries, arterioles, capillaries, venules and veins), and blood

transporting oxygen, nutrients, hormones and wastes throughout the body

Lymphatic vascular system is made up of what? What’s it responsible for?

lymph capillaries and vessels that drain extracellular fluid (lymph) from the tissues

What is the immune system

a collection of organs and aggregates of lymphoid tissue that work to prevent disease as part of the immune system

Lymphoid organs (4)

• Lymph nodes

• Spleen

• Thymus

• Tonsils

What is the most common site for microbial invasion?

The mucosa

What protects mucosal surfaces from microbial invasion?

MALT- small aggregates of lymphoid tissue called mucosa-associated lymphoid tissue

Where can MALT be found?

the gastrointestinal tract (e.g. peyer's patches), respiratory system, genitourinary system, and integumentary system

AND Bone marrow- makes lymphocytes

Define pilosebaceous apparatus

Contains the hair follicle, sebaceous gland, and arrector pili muscle 

Which layer of the skin contains small blood vessels, nerves and sensory receptor 

Dermis 

Insulating layer of the skin

Subcutis

Epithelium in the epidermis 

Nonkeratinized and keratinized stratified squamous

The skin has 4 epidermal layers

False- it has 5 (stratum layers- CLGSB)

In this layer of the epidermis, cells progressively become more flattened and darkly stained as they migrate towards the stratum corneum

Stratum granulosum 

Keratinocytes can be found in the _______

Stratum spinosum

_______ is responsible for keratinizing keratin 

Keratinocytes 

Cellular makeup of a keratinocyte 

low cuboidal

polyhedral shape, pale staining nuclei but prominent nucleoli

Contains ribosomes and mitochondria (can see granularity/foaminess cytoplasm)

Linked by desmosomes 

Melanosomes are transferred to the keratinocytes where they deposit melanin when exposed to UV light

True

Describe a meloncyte and where it would be found

Round with clear cytoplasm’s found in the basal layer

Melanocytes function

Synthesize melanin - skin color, UV protection

Melanin is synthesized by _______ enzymes

tyrosinase

What is the purpose of Langerhans cells

Immune response (antigen recognition and processing)

Where are Langerhans cells found and what do they look like

Throughout the epidermis but most prevalent in the spinosum 

Irregular shaped nuclei with nearly clear cytoplasm 

What can be used to identify Langerhans cells

CD1 - IHC staining

Merkel cells function, what they look like, and staining that can be used to see them

Touch receptors

Round cells with pale cytoplasm and round, pale nuclei- hard to see microscopically

IHC staining

Which of the following is contained within the papillary dermis:

-Elastic

-Loose collagen 

-Hair follicle bulb

-Lymphocytes

Hair follicle bulb

What is a skin appendage and a few examples

Specialized structures in the dermis and occasionally upper subcutis

• hair follicles

• sebaceous glands

• eccrine glands

• Ducts

• apocrine glands

Sebaceous glands secrete?

Sebum

Which of the following is not apart of the pilosebaceous apparatus:

-Sweat gland

-Hair follicle 

-Sebaceous gland

-Arrector Pili muscle 

Sweat gland 

Innervation and nerve ending systems

Afferent and Efferent system

What is a part of the Afferent system and their functions (3)

Free nerve endings - pain/itch receptors, temperature detection

Meissner’s corpuscles - Touch sensation, papillary dermis of hands/feet

Pacinian corpuscles - Deep pressure and vibration, deep subcutis

Function of the Efferent system

Supplies vessels and skin appendages, Responsible for blood flow, stimulates the arrector pili muscle and eccrine sweat glands 

What tunica of an artery contains the endothelium?

Tunica intima

The blood supply of the larger arteries and veins is called the _____

Vasa vasorum

Which type of artery has a thick muscular tunica intima 

NONE- tunica intima is a THIN layer 

Compared to muscular arteries, elastic arteries have more elastic but less _____

Smooth muscle

The this, wavy band of elastic fibers that appears to divide the tunica intima and the tunica media is the internal elastic lamina

FALSE_ external elastic lamina (EEL)

The most common type of capillary is

Continuous 

Three types of capillaries and here we would find them

Continuous- muscles, skin, CNS 

Fenestrated- kidney, intestines 

Sinusoidal- liver, spleen, lymphoid organs 

Function of the capillary and their layers

Supplies sweat glands with water and proteins

consists of one layer- intima

What type of capillary is commonly found within liver, spleen and bone marrow

Sinusoidal

The smallest branch of the venous system is….

Venule

Venules then veins (sm to L)

How does lymph move with the lymphatic vessels

Lymph flows sluggishly, contractions of surrounding smooth or skeletal muscles force the lymph to move forward. Valves prevent a backflow of collected lymph

The inner layer of the heart wall is called the

Endocardium

B and T lymphocytes can be readily distinguished as type specific in H&E stained lymph node

False- need IHC staining 

Lymph enters the lymph node via the ______ and leaves vie the ______

afferent vessel, efferent vessel

Flow of lymph

1. Enters via afferent lymph vessel on convex surface

2. Drains into subcapsular/marginal sinus

3. Cortex

4. Medulla

5. Lymph leaves via efferent lymph vessel

What does lymph become in the blood stream

plasma (sub-clavian)

T cell mutation occurs in the ______

Thymus 

What are the spherical structures seen in the medulla of the thymus?

Hassall’s corpuscles

Where do immature T cells migrate from to the thymus 

Bone marrow 

Describe Hassall’s corpuscles

Epitheliocytes, whorls and swirls in

The spleen consists of a cortex and medulla

FALSE- consists of red and white pulp

What is the term for the lymphatic (T/B cell) region of the spleen

White pulp

Which is the largest lymphoid organ 

Spleen

What is the hilum

Splenic artery and vein, where the efferent lymphatic system is

Plasma cells are more readily found in the lymph node and spleen, in comparison to the thymus

True

What type of microtomy artifacts may we find on a section of spleen

chatter

Parched earth

Formalin pigment

Tissue separation - CT

What are the localized concentrations of lymphocytes that are seen in the respiratory tract, genitourinary tract, and gastrointestinal tract?

MALT 

This description best fits with which cell type-

“Activates in the presence of an antigen and differentiate to plasma”

B cell

The journey of a B-cell

B-cells proliferate and transform into plasma cells in the presence of antigens to which they secrete antibodies into the blood/lymph that bind and inactivate foreign substances

Hair follicles have thermoregulation functions

True- goosebumps (the arrector pili muscle contracts)

The process of sebaceous glands producing sebum is called ___________

Holocrine secretion

Eccrine sweat glands function and where to find them

Produces sweat (evaporation of sweat reduces temp) for thermoregulation

Found in palms, soles, forehead and axillae

Functions of dermal vasculature

Provides nutrition

Increased blood flow facilitating heat loss in hot conditions

Decreased blood flow facilitating heat loss in cold conditions

Unique features of lymph 

Free of cells

Lymph is darker than plasma 

Where does lymph enter the venous system

base of the neck

What the function of lymph vessels

Drainage system for removal of fluids from tissue spaces

Function of white pulp, what organ its found in and what cells we would find in it

Immunologically monitors blood

spleen

B/T cells are found here, plasma cells, macrophages

Function of Red pulp, what organ its found in and what cells we would find in it

Spleen

Recycles iron and heme, stores platelets, immunoglobulin production from plasma, removes old/damaged matter

What regions are included in MALT

Tonsils, peyers patches, lymphoid tissue in the respiratory system, genitourinary tract, breast, GI tract

What cells populate the MALT

Lymphocytes (T/B cells)

Plasma cells

Macrophages

Function of MALT

Encounter antigens passing through the mucosal epithelium 

Two types of epithelium in the tonsil

Palatine- nonkeratinized stratified squamous epithelium

Pharyngeal tonsil (adenoids)- Pseudostratified columnar epithelium

Which lymphoid structure has two types of epithelium?

Tonsils (palatine, pharyngeal-adenoids)

Two types of immune responses by the body

Cell-mediated (t cell) and Humoral (B-cell)

apocrine glands 

Sweat glands found in the arm pits, larger than eccrine 

Specific to hair follicles

Two regions of eccrine glands

Secretory- bigger lumens, less basophilic

Duct- excretes- smaller lumen, more basophilic

Average diameter of a capillary 

5-10, more specifically 8-10 microns 

Function of perkinje fibers

Located beneath the endocardium- conduct cardiac action, electrical impulses to the ventricles in turn pumping blood

Differentiate between the endocardium, epicardium, and myocardium of the heart

Endocardium- innermost layer

Epicardium- outermost layer

Myocardium- middle layer (muscle)