Module 1 - Skin and Cardiovascular System Flashcards
What are the layers of the skin?
epidermis, dermis and hypodermis
Describe the epidermis ?
Stratified barrier, mostly keratinocytes, no circulation
Describe the dermis?
- Protein fibres for strength
- Collagen
- Elastin
- vascular (nourishes the epidermis )
- Not shed
Describe the hypodermis?
- Adipose tissue
- insulation
What are the functions of the skin
- Protect underlying tissues
- Maintain normal body temperature
- Detect touch
- Produce melamin
- Produce keratin
- Synthesis of vitamin D
- Store lipids
What composes the cutaneous layer and describe them?
Epidermis and dermis
dermis
- Papillary layer - creates a wavy border between the epidermis and dermis layer to increase the surface area. There needs to be a large surface area in order to allow the nutrients to come up to the epidermis from dermis .
- Reticular layer - primarily collagen - provides strength and rigidity
Name the layers within the epidermis ?
- Stratum corneum
- Stratum lucidum ( only found in thick skin)
- Stratum granulosum
- Stratum spinosum
- Stratum Basale
Stratum Cornuem
Dead, dried out cells without nuclei
- this layer can removed with just tape
Stratum granulosum
- Contains granules that promote dehydration of the cell
- cross linking of keratin fibres
- Waxy material is secreted into intercellular spaces
Stratum Spinosum
- Intercellular bridges called desmosomes link the cells together
- the cells become increasingly flattened as they move upwards
Stratum Basale
- Tall regenerative cells
- As the basal cells divides, a daughter cells migrates upwards to replenish the layer above
types of epithelial cells?
squamous, columnar, cuboidal
What type of layer is the epidermis
stratified squamous
Signs of skin aging
- thin epidermis
- thin dermis
- slower skin repair
- drier epidermis
- impaired cooling ( less sweat)
- less pigmentation (grey hair)
What are the accessory structures to the skin
- Hair
- Sweat glands
- Receptors
- Nails
Describe the function of hair ?
- located all over the body except where thick skin is ( palms and sole of the feet)
- consists of
- hair shaft
- Hair follicle
- arrector pilli muscle
- sebaceous gland
- produces sebum - gives natural moisturiser and water repellent
- Acne
- blockage of hair follicles + infection
- increased sebum increases acne risk
- blockage of hair follicles + infection
Describe the function of sweat glands
- eccrine ( everywhere thermoregulation)
- apocrine (specailised)
- situated deeper into the skin, release into the base of hair follicle , they continuously secrete a fatty sweat into the gland tubule
Describe the function of nails ?
- protect finger nails
- enhance sensation
- sensory receptors require deformation
name the different receptors
- Free nerve endings
- Tactile discs
- Tactile Corpuscles
- Lamellar Corpuscles
- Bulbous Corpuscles
function of the free nerve endings?
detect pain and temperature
these are most common receptor in the skin
Tactile discs
texture, shape and fine touch
Tactile corpuscles
Located in the papillary layer of the dermis
Fine touch, pressure and low frequency vibration
Lamellar corpuscles
scattered deep in the dermis and hypodermis
deep pressure and vibration
Bulbous corpuscles
Located on dermis and subcantaneous tissue
Pressure and skin stretch
where is melanin produced ?
melanocytes cells
how is melanin transfereed?
melanin is transferred to the epithelial cells via melanosomes - these are vesicles containing melanin
Whats distinguishes a mole?
it is a cluster of melanocytes - hence more cells
- overproliferation can be caused by sun exposure
what distinguishes a freckle?
Melanocytes over producing melanosomes
- over production triggered by the exposure of sun
Where are melanocytes found?
in stratum basale as pigment is not shed
where are melanosomes found?
throughout the epidermis - these are shed with keratinocytes
why is vitamin d needed?
it is needed for normal calcium metabolism and strong bones
Basal cell carcinoma?
- common but relatively gentle
- originates in stratum basale
- metastasis is rare
Malignant melanoma?
- rare but deadly if not treated
- originated in melanocytes
- highly metastatic
- mortality rate dependent upon tumour
why does melanoma depth matter?
the thicker the tumour, the deeper they go into the dermis, the more likely they are to get into the circulatory system and sympathetic system and then make their way around the body and by chance if they land in an organ it will cause problems
tattoo?
how do we constrict blood flow in the upper layer of the skin?
blood flow are be constricted in the upper layer of the skin through pre capillary sphincters , these are bands of smooth muscle at the start of capillary beds, if we constrict smooth muscle in the arteries or smooth muscle in the pre capillary sphincters we can constrict the blood flow in the upper layer of the skin.
describe the process to reduced skin blood flow
- smooth muscle in walls of arteries and pre capillary sphincters innervated by the sympathetic nervous system (SNS)
- Noradrenaline acts on alpha adrenergic receptors in this vascular smooth muscle in the skin
- g-protein coupled receptors to intracellular 2nd messengers leads to increased intracellular ca++ leads to constriction
how do you get increased blood flow?
decreasing the SNS activity therefore causes relaxation (dilation) of the arteries to skin.
What are the primarily mechanisms of heat transfer?
conduction
evaporation
convection
radiation
conduction?
involves the transfer of heat to objects or media which are in contact
Convection?
involves the transfer of heat to air by conduction followed by the movement of he air away form the skin which maintains the gradient for heat loss from the body
Evaporation?
when water evaporates from the body surface the heat energy required to cause the water to evaporate is also lost.
Radiation?
causes heat loss in the form of infrared rays
how are eccrine sweat glands turned on?
they are innervated by the SNS
- sympathetic cholinergic
i. e release ACH onto mAChRs - some eccrine sweat glands can also be stimulated by adrenaline in blood acting on B receptors - ie nervous sweating
What are the responses when the body temperature increases?
- Behavioural changes
- Respiratory rate increases
- decreased SNS leads of activation of alpha 1 on skin blood vessels which leads to vasodilation
- increased SNS cholinergic activation of mAChRs on sweat glands leads to sweating
What are the responses when the body temperature decreases?
- shivering
- increase tone of skeletal muscles - Non- shivering
- increase of sympathetic nerve activity and increase in circulating adrenaline
- increased cellular metabolism
- heat produced instead of ATP - Thyroxine
- increases basal metabolic rate - Countercurrent exchange
- exchanging blood before it reaches surface and loses heat
what is the function of the arrector pili muscles
- attach hair follucles to upper dermis
- contraction pulls hairs upright and goosebumos
the muscle is innervated by SNS (alpha 1 receptors)
first degree burn
- superficial - only involves the outer layer of the epidermis
- red/pink , dry, painful
- usually no blisters
- skin remains a water and bacterial barrier
- heals in 3-10 days
Second degree burn
- epidermis + varying amounts of dermis
- painful , moist , red, blistered
- usually heal in approx 1-2 weeks
deep 2nd burn
- may include waxy looking areas
- hair follicles, sweat glands may remain intact
- some tactile receptors may be lost
- usually heals in 1 month
third degree burn
- extended into subcutaneous tissue and may involve muscle and bone
- varied colour to deep red or black
- no pain as sensory nerve ending have been destroyed
- weeks to regenerate
function of the pulmonary circuit
taking deoxygenated blood from the right hand side of the heart to the lungs for oxygenation of blood
describe the vascular system
a closed supply and drainage system - a continuous loop
describe the lymphatic system
a open entry drainage system - a one way system
function of the systemic circuit?
Takes oxygenated blood and pumps from the left hand side of the heart to everywhere inside the body.
Function of the lymph circuit ?
this is present in both circuits, this accumulated any blood that leaves the vascular system. Before re uniting the accumulated blood, the fluid goes through the lymph nodes which gets rid of any miscrobes.
Explain the supply side
- arteries are the only supply path
- major arteries are situated deep to avoid damage
- important structures often receive supply from two different arteries
- arteries change their names at each major branch
explain the exchange system?
- capillaries of varying degree of permeability
- continuous (tight)
- fenestrated (leaky)
- Sinusoidal (very leaky)
Explain the drainage system?
3 pathways for drainage
- deep veins
- superficial veins
- lymphatics
- their cross sectional area is twice as of arteries as arteries are bigger in size
what is the shape of the heart
the heart is blunt cone shaped, it has a pointed end which is called the appex and a broad end called the base
where does the heart sit in the body
the heart sits within our chest within the thorax flanked by the 2 plural cavities.
where does the base sits ?
between the 2nd and 3rd ribs
where does the appex sit?
between the 5th and 6th ribs
explain the process of blood from right atrium and ventricle include the veins or arteries, which ever one applies
- the superior vena cava drains everything from the head, neck, chest and upper limbs
- The inferior vena cava drains blood from everywhere from below the diaphragm.
- coronary sinus is the drainage of the heart itself. Once we have supplied the heart with blood, it drains that venus blood that has been deoxygenated straight back to the right atrium, into the ventricular chamber
explain the process of blood from left atrium and ventricle include the veins or arteries, which ever one applies
Once we have achieved reoxygenated blood, blood drains back through the 4 pulmonary veins into the heart. The veins come into the left atrium into the ventricle. When ventricular contraction occurs, blood moves into the aorta.
what structures help to receive blood into the right atrium
superior vena cava
inferior vena cava
coronary sinus
what structures help to receive blood into the left atrium
4 pulmonary veins
name the layers of the heart
- epicardium ( uppermost layer)
- myocardium ( muscle layer)
- Endocardium - innermost layer )
- pericardium
describe the pericardium
- layers?
this is where the heart sits in, it is a lubricated sack, it helps to protect the heart
- the outermost layer is the fibrous pericardium
- the inner most layer is the serous layer
- the serous layer can be divided into 2 layers - parietal (superficial layer) and visceral
Describe the endocardium
- squamous epithelial cells
- loose irregular fibrous connective tissue (FCT)
- small blood vessels
- purkinje fibres
what does the pericardial cavity provide
this provides potential space between the visceral and parietal pericardium. Serous fluid is secreted into this cavity to allow frictionless movement of the heart.
why is there a difference in the thickness between the right and left ventricle myocardium ?
there is difference due to the journey of blood to organs, on the right side it is not as thick due to the shorter journey from the heart to the lungs hence need to push the blood with less force compared to the left side, as from the left side we need to pump blood to everywhere