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
describe epicardium?
visceral layer
large blood vessels
loose irregular fibrous connective tissue
what is the name of AV valve on the right side
tricuspid valve`
what is the name of AV valve on the left side
bicuspid valve
what is the function of semilunar valve
prevent blood from returning to the ventricles during filling ( diastole)
what is the name of the semi lunar valve on the right side
pulmonary valve
what is the name of the semi lunar valve on the left side
aortic valve
during diastole av valves are open/close
open
during systole av valves are open/cose
closed
explain the process of systole ?
the ventricle muscles are contracting, the pressure exerted onto the ventricles leads to the ventricle squeezing the blood, the blood can go in 2 directions, but due to the av valve closed, the blood is pushed out to the outflow artery.
explain the process of diastole ?
filling from the atrium chamber down to the ventricles. This is when the heart muscle is relaxed, the ventricle system is relaxed, the av valve is open allowing blood to flow into the ventricle. the semi lunar valve are shut
what are attached to the av valves on both sides
papillary muscle and chordae tendinae
how doe papillary muscles and chordae tendiae help?
when the pressure starts to go up in the ventricles, the tension moves to the papillary muscle so hence these structures prevents from the leaflets to slam shut when they about to shut.
describe a cardiac muscle cell structure?
- striated
- short, branched cells
- one or occasionally 2 nuclei
- central (oval shaped ), nuclues
- cytoplasmic organelles packed at the poles of the nucleus
- interconnected with neighbouring cells via intercalated disks
what artery branches of the Aorta
coronary arteries (left and right)
adhesion belts ?
linking actin to actin
desmosomes?
linking cytokeratin with cytokeratin
gap junctions?
electrochemical communication
what are punkinje cells ?
these are cardiac muscle cells which are no longer contract, they have become modified for this role carrying conduction potentials
explain the conduction pathway
the conduction path begins at the top of the atrium known as the SA node. The SA node creates contraction potential which pass through the atrial chambers via the internodal branches through he right atrium to the left atrium. Than all these internodal pathways in the artriuml chamber then mateet at a single point called av node, this is the gateway to the ventricular chamber. From the AV node we go down into the ventricular spectrum, between the right the left ventricle we start off in the AV bundle and then that branches into right and left bundles
describe the features of purkinje cells
- some peripheral myofibrils
- central nuclues
- mitochondria, glycogen
- lots of gap junctions
- some desmosomes and few adhension belts
name the 3 layers of blood vessel walls?
- tunica intima
- tunica media
- tunica adventitia
name the layers within the tunica intima
- endothelium
- sub-endothelium
- interbal elastic limina
endothelium?
a simple squamous epithelium which lines up the lumen of all vessels
Sub - endothelium ?
a spare pad of loose FCT cushioning the endothelium
describe tunica media
- smooth muscle
- variable amount of connective tissue fibres- mainly elastin and collagen
- thickness of the media is proportional to both vessel diameter and blood pressure
describe tunica adventitia ?
- loose fibrous connective tissue with a high content of collagen and variable amount of elastin
- in larger vessels this layer contains vasa vasorum
- lymphatics and autonomic nerves are also found in this region
function of arteriole
the resistance vessels of circulation determine blood pressure
describe veins
- low pressure, large volume transport system
- one way flow
- capacitance vessels
describe the layers with veins
- intima
- media - much thinner than arteries, a few layers of smooth muscle
- adventita - often the thickest layer of a vein
what is the shape of vein?
irregular, flattened shape with large lumen and thin wall
describe capillaries?
- very thin walls
- large total cross sectional area of a capillary bed
- slow and smooth blood flow
what is a vascular stunt
when the blood goes from supply to drainage without going to the gas exchange beds
explain the continuous capillaries
- 8-10 in diameter
- single file of cells
fenestrated capillary?
leaky
- 8-10 in diameter
- single file of cells
sinusoidal capillary?
- 30-40 um in diamter
- incomplete basement membrane
functions of the lymph vascular system ?
- drains excess tissue fluid and plasma proteins from tissues and returns them the blood
- filters foreign material from the lymph
- screen lymph for any antigens and responds by activating immune cells
- absorbs fat from intestine and transport to blood
describe the structure of the lymphatic system?
lymphatics vessels
- commence as large, blind ending capillaries
- from small intestine vessels called lacteals drain fat into a vessel called cisterna chyli
- larger collecting vessels which have numerous valves
name the veins in legs
- common iliac vein
- external iliac vein
- femoral vein
- great saphenous vein
- Popliteal vein
- posterior tibial vein
- plantar venous ar h
name the arteries in the legs
- common iliac artery
- external iliac artery
- femoral artery
- popliteal artery
- posterior tibial artery
- planar arch
name the structures involved in the lymph on the left side
everything below the diaphragm goes through the left subclavian vein and than into the thoracic duct.
name the structures involved in the lymph on the right side
face, body than into the right subclavian vein
describe the breast drainage ?
axillary node -> right lymphatic duct-> right subclavian vein
explain the mechanism of cardiac contraction
- calcium levels go up, more calcium is released from the sacroplasmic reticulum (SR)
- myosin binds to actin to form cross bridge
- myosin pulls on actin to shorten the sarcomere and generate force
how do we increase the force of cardiac contraction?
by increasing the level of calcium released leads to an increase of cross bridges and hence more pulling of myosin so therefore a greater force of contraction.
explain the mechanism of cardiac relaxation
- decrease in the levels of calcium as the calcium is pumped back into the SR
- cross bridges release when ATP binds to myosin
- reduction in force means the heart can relax
- all myocyte relax each beat
what is systole ?
relaxation or contraction? and rising or falling pressure
contraction and rising pressure
what is diastole ?
relaxation or contraction? and rising or falling pressure
relaxation and falling pressure
what does systolic mean?
highest point
what does diastolic mean?
lowest point
what is hypo-extension?
when the pressure goes below the lowest point
what is hyper extemsion?
when the pressure goes above the highest point
what are electrical cells and give an example?
- they make up 1% of the heart cells
- pale cells with striations
- low amounts of actin and mysoin
e. g purkinje and av nodal cells
what are contractile cell?
- make up 99% of the hearts cells
- high actin and myosin
- have striatedh appearance
how does the propagation of the cell wok
- depolarisation starts from the SA node
- it then travels to the neighbouring cells
- in contractile cells - the levels of calcium goes up
how does the impulse spread between both types of cardiac cells?
the impulse mostly travels through the intercalated disks , these contain gap junctions, the gap junction provides low resistance to electric current, hence the pulse is able to pass through with increased speed
what is a functional syncytium?
when all the cells in the heart behave as one
what are the 3 ways the SA node sends it signal ?
- send the signal directly into the right atrium
- to move the signal into the inter-atrial bundle over the left atrium . the inter-atrial is comprised of electrical cells which will cause both the atria to contract
- send the signal through internodal bundles
what is the function of the av node
to collect the signal form the SA node and put a pause on it, it does this so both the atria and ventricles do not contract at the same time, as if this happens then the blood will just squeeze out of everywhere
what role do purkinje fibres play in this conduction pathway?
the signal travels back up the purkinje fibres
state the order of the conduction pathway
- sa node
- internodal bundles
- AV node
- AV node bundle ( branches into 2 )
- Purkinje fibres
lubb?
- when the av valves first snap shut , the sound heard is called lubb
dupp?
when the semi lunar valve snap shut we get the second sound called dupp
why is there a pressure difference between the arteries and vein?
this allows the blood to be moved around the body - the difference is the driving force for blood flow
what happens when the “blood flows in”?
- it fills the arteries
- increases the arterial blood volume
- raises the arterial pressure
what happens when the “blood flows
“ out?
- drains in the veins
- decreases the arterial blood volume
- lowers the arterial pressure
what is the arterial blood volume and pressure determined by ?
The balance between the blood flowing in and out
whats the equation for MAP
MAP= CO x TPR
Equation for CO
CO= SV x HR
what does stroke volume stand for
contraction strength
what does heart rate stand for?
contraction speed
what are baroreceptors?
they are stretch receptors which sense a change in the stretch in the arteries as if the blood pressure increases, the arteries expand a little bit. They are continuously signalling the brain how the pressure is in the artiers
where are baroreceptors heavily concentrated ?
Aortic arch and carotid artery
what is the afferent input to maintain the MAP?
from periphery baroreceptor
what does the sympathetic system do?
hardwired into the sa node, it tells the heart to fo contract faster hence, more calcium is released so more cross brdges are formed and hence a stronger contraction
what does the parasympathetic system do?
it tells the av node to put longer pauses, hence slowing thr signaling
why is high pressure in the blood vessels good?
it allows full control of the blood
name the order of vessels as the MAP decreases?
aorta, elastic, muscular arteries, arterioles, capillaries, venules,
how is the flow split up?
the flow splits up by the arterial circuits being in parallel with each other
why is the flow split up?
BDE
this allows to control the blood flow as it needed to meet the metabolic demand, as if were exercising more blood can be flowed to the muscles, skin and heart
during exercise where is the decreased blood flow?
GI and kidney
during exercise where is the increased blood flow?
heart
muscle
skin
What is TPR?
it is the resistance of our blood vessels that allow the blood to drain into the capillaries
in the muscle increased flow means decreased…
resistance
what is the relation of the radius and resistance ?
The bigger the radius the less resistant it is on the blood
what is the process of vasodialtion?
the process of relaxing the smooth muscle around the vessel so the vessel is able to get larger and hence making the arteriole bigger, so more blood flows
what is the process of vaso constriction?
the process of contracting the smooth muscle around the blood vessel so we can constrict the amount of blood flowing through it. i.e when exercising we need to constrict the blood flow tot the GI
what is the equation of resistance and radius
resistance = 1/r^4
where is most of the blood found?
systemic veins
define complaince?
the extent to which a vessel allowed deformation in response to an applied force
are veins or arteries compliance ? why?
veins are compliance as they have a shit wall hence the shape of veins is easily distorted which allows more blood to flow
equation for compliance?
compliance = v/p
what is a survival valve?
we associate this with the veins as in an emergency the veins are able to give blood to the arteries it is losing blood
what is venoconstriction?
we constrict the veins so blood can be pushed into the heart and into the arteries
what is the starlings law of heart
the more stretched muscle fibres are before contraction, the stronger the contraction so the greater the return of venous blood back to the heart, the greater the blood is pushed into the arteries
what are the functions of the blood
transport
coagulation
immune response
what does transport include?
- gases
- nutrients
- water
- hormones
what is coagulation?
- this is to prevent bleeding
transporting platelets and coagulation factors to the areas of a bleed
what is comprised of the plasma
- plasma proteins
- other solutes
- water
what forms the formed element
- platelets
- white blood cells
- red blood cells
hematopoiesis ?
the process of formation of of blood cells
hemocytoblasts ?
these are progenitors for all blood cells
where are hemoctyoblasts stored ?
in the red marrow in the bones
erythropoietin (EPO)
is a molecule which tells hemocytoblasts to produce red blood cells which leads to firing up a specific pathway
what is the shape of RBC and why are they shaped like that?
they are biconcave disc shaped. This allows for them to have
- a larger surface area to volume ratio
- allows for efficient diffusion for gases
- flexibility for movement through narrow capillaries
characteristics of red blood cells
- contain large amounts of hemoglobin
- one-third weight of RBC
- uses iron as part of the heme structures
- 4 heme units, so each hemoglobin can bind 4 oxygen molecules
what is hematocrit?
is the fraction of your blood which is composed of red blood cells
anemic?
associated with iron defiency and since iron is needed to bind heme groups, the blood will be carrying less oxygen
polycythemic?
to many red blood cells so crowding out in the plasma that means the blood is getting thick, hence difficult to push the blood around due to an increase in the resistance due to thickness. Hence need to provide extra force to push the blood increasing the blood pressure .
