HUBS192 Progress Test 1 better one

What is hematopoiesis?

the formation of all blood cells

What are hemocytoblasts?

progenitor cell for all blood cell types

Where are hemocytoblasts found?

red bone marrow

What does erythropoietin do?

signals hemocytoblasts to differentiate into RBCs

What are platelets?

cell fragments

What function do platelets have?

help to stop bleeding/clotting

What are the three major functions of blood?

transport, immune response and coagulation

The "formed elements" of blood are mainly made up of what?

cells: platelets, WBCs, RBCs

The formation of RBCs is called?

erythropoiesis

What is the main function of RBCs?

store and carry oxygen

What role does testosterone have on RBC production?

enhancer of erythropoietin, stronger signal and more RBCs produced

Low RBC count is called?

anemia

High RBC count is called?

polycythemia

Name one consequence of polycythemia

thickened blood and high BP, strain on heart

What is the main component of plasma?

water

Relate the form of RBCs to their function

large SA:VOL, flexibility, efficient gas diffusion

What are three functions of the skin?

protection, regulation, and sensation

What are the three layers of the skin called?

epidermis, dermis, hypodermis

Name the cells that make up the epidermis

squamous epithelial

What is the name of the epithelial cell that dominated the epidermis?

keratinocytes

Is the epidermis vascular or avascular?

avascular

What is the main function of the epidermis?

protection from external environment

Name the five layers of the epidermis

stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale

What layer of the epidermis is only found in thick skin?

stratum lucidum

Is the dermis shed?

no

Is the dermis vascular or avascular?

vascular

What is the superficial layer of the dermis called?

papillary layer

What is the deep layer of the dermis called?

reticular layer

Name the two protein structures found in the dermis

collagen and elastin

What layer of the skin are blood vessels, lymphatics, nerves and accessory structures found?

dermis

What is the other name for hypodermis?

subcutaneous layer

Adipose tissue serves what function in the hypodermis?

insulation and links skin to rest of the body

Why does thick skin have the stratum lucidum?

for extra protection from wear and abrasions

The body is mostly covered in .......... skin

thin

What causes sagging in the skin?

epidermis becoming thinner and drier

The skin becomes thinner because.......?

decreased basal cell activity

The skin becomes drier because........?

sebaceous glands produce less secretions

A decline in melanocyte activity leads to ........ in the skin?

less pigmentation in skin and hair

Name two other effects that age has on the skin

impaired cooling due to less active ecrine glands and slower skin repair

What three features does the hair consist of?

hair follicle, hair shaft and arrector pili muscle

What is the function of sebaceous glands?

produce sebum for moisture and water repellent

Acne is caused by........?

blockage of the hair follicles and infection

What are the two kinds of sweat glands?

apocrine and eccrine

Eccrine sweat glands are found ....... on the body

everywhere

What is the main function of the eccrine sweat glands?

secrete sweat onto surface of the skin for thermoregulatory properties

Are apocrine sweat glands influenced by the nervous system or hormones?

hormones

What kind of sweat gland is found deeper within the skin?

apocrine

Where do apocrine sweat glands empty?

base of the hair follicles

Name two locations where apocrine sweat glands are found

nipples and groin

Name the two functions of nails

enhance sensation and protect fingertips

Free Nerve Endings

mostly unmyelinated and small diameter fibres, respond to temp, painful stimuli, movement, pressure, itch, bending of hairs

Tactile Discs

free nerve endings in deepest layer of epidermis, associated with large disc shaped epidermal cells, abundant in fingertips, sensitive to physical features eg, shape, texture, edges, fine touch and pressure

Tactile Corpuscles

papillary layer of dermis, abundant in hairless skin, encapsulated, sense delicate/fine discriminative touch, shape and textural changes (Braille), light pressure and low frequency vibrations

Lamellar Corpuscle

deep in dermis and hypodermis, single dendrite within concentric layers of collagen fibres and speacialised fibroblasts, dendrite ONLY stimulated by deep pressure, senses deep pressure (only when first applied) and vibration, rapidly adapting

Bulbous Corpuscles

dermis and subcutaneous tissure, nerve endings wrapped around collagen fibres and within capsule, sensitive to sustained deep pressure, stretching/distorting of skin, also aids in signalling degree in joint rotation (proprioception)

What is the main function of melanocytes?

produce melanin pigment

Where are melanocytes found?

stratum basale

What are melanosomes?

vesicles that contain melanin pigment

Where are melanosomes found?

throughout the epidermis

What is the main function of melanin pigment?

to absorb and protect cells from UV light and damage

Are melanosomes shed?

yes

A cluster of melanocytes is called? And overproliferation is caused by what?

mole, sun exposure

What occurs when melanocytes over-produce melanosomes?

freckles

The over-production of melanosomes is triggered by what?

sun exposure

Why is vitamin D important?

essential for normal calcium metabolism and maintaining bone strength

Why is UV exposure important for Vit D?

UV exposure is essential for synthesis of Vit D

Are highly pigmented or lower pigmented people more susceptible to Vit D deficiency?

highly pigmented people

Basal cell carcinoma

common, relatively benign, originates in stratum basale, metastasis is rare

Malignant melanoma

rare but deadly if untreated, originates in melanosomes, highly metastatic

What three factors does the mortality rate depend on for malignant melanoma?

thickness, location, depth

What layer of the skin is tattoo ink needed to be deposited into to ensure the pigment isn’t shed overtime?

dermis

Where is tattoo ink captured?

immune cells and scar tissue

What happens when tattoo ink is captured in lymph nodes?

can look very similar to melanoma cells

What vessels are "supply" structures?

arteries

What are the drainage structures?

veins and lymphatics

What structures are involved in gas and nutrient exchange?

capillaries

Name the three types of capillaries

continuous, fenestrated and sinusoidal

Does blood flow at high pressure through capillaries?

no, smooth and slow

What role do precapillary sphincters play in capillaries?

they are bands of smooth muscle cells which constrict and block pathways, controlling the movement of substances

What is the most common form of capillary and where is it usually found?

continuous and everywhere

Are fenestrated capillaries the leakiest?

no

What is the diameter of continuous and fenestrated capillaries, what does this mean in terms of RBCs?

8-10micrometres, RBCs travel in single file

Which type of capillary features an incomplete basement memebraine?

sinusoidal

What are fenestrations?

pores in the capillary endothelium that help to transfer plasma/fluid out of the capillaries

What kind of muscle are continuous capillaries made out of?

skeletal and cardiac

Where are fenestrated capillaries found?

kidneys and small intestine

Why are sinusoidal capillaries larger and "leakier"?

to allow for large amounts of plasma and blood to travel through and greater nutrient exchange through diffusion

Describe the structure of lymph capillaries

thin-walled, no RBCs, valves and run alongside veins and arteries, large blind-ended capillaries

What do larger lymphatic vessels have to prevent backflow?

numerous valves

What are the functions of the lymph vascular system?

drains excess tissue fluid and plasma proteins from tissues, filter foreign material from lymph, "screens" lymph for foreign antigens and responds by releasing antibodies and activated immune cells, absorbs fat from intestine and transports to blood

What structures do lymph nodes contain?

afferent and efferent lymphatics and blood vessels

What is the lymph vascular system?

open entry drainage system

What are the three layers of blood vessel walls?

tunica intima, tunica media, tunica adventitia

What are the three layers of the tunica intima?

endothelium, sub-endothelium, internal elastic lamina

Why does the thickness of the tunica media differ between veins and arteries?

thicker in arteries to withstand the force of high blood pressure and the "pulse"

What layer of the blood vessel wall is often the thickest of that of the veins?

tunica adventitia

Where can lymphatics, autonomic nerves, collagen and elastin be found within the blood vessel walls?

tunica adventitia

What is thickness of tunica media proportional to?

Both the blood vessel diameter and blood pressure.

Why are major arteries situated deep within the body?

they are crucial for survival and so to avoid damage

Do arteries or veins have valves?

Only veins, since they are low pressure and need to prevent backflow when traveling back to heart