module 5.3 the dermis as we mentioned previously the dermis has two distinct layers the upper layer is called the papillary layer made out of areolar tissue now what are you going to find in the papillary layer contains tactile corpuscles the old school terminology was meisner corpuscles and what do they do they respond to light touch because of their location close to the surface this is also where we're going to find a lot of capillaries and those capillaries then feed and provide nourishment to the epidermis since the papillary is made out of areolar tissue it acts as a highway to cells of the immune system so they can get to any pathogens that might have breached our skin and last of all there are dermal papillae present those are those wavy projections that go up and down where the papillary layer comes in contact with the epidermis okay what are the features of the reticular layer this is the deeper layer it's mostly made out of dense irregular connective tissue and as we learned in the tissue chapter the dense irregular connective tissue has lots of collagen fibers which provide strength to the dermis we also have quite a few elastic fibers embedded into the dermis and it gives it the ability to stretch and return to its original shape so there is something called the pinch test for hydration if you pinch the skin if it remains in a peak that indicates that your patient is not well hydrated if you pinch it and it immediately returns to its original flat position that's a good sign that your patient is well hydrated what else do we find in the reticular layer the sensory structures are called lamellated or pacinian corpuscles now since these are deeper than what the tactile corpuscles are these sensory receptors respond to deep pressure and vibration rather than light touch we also find our blood vessels those are mostly arterials sweat glands hairs and sebaceous glands which we'll cover in just a little bit let's use this picture to identify and discuss our two layers of the dermis so the dermis is made up of the papillary layer on top and the reticular layer on the bottom the papillary layer is made out of areolar tissue remember areolar tissue has lots of space so if we happen to cut or breach our skin and pathogens make it inside the body white blood cells can use this as a highway to quickly get to the point where we have been invaded what else do we find in the papillary layer we find some sensory structures called tactile corpuscles or old school meisner corpuscles what's going to make this nerve ending fire off light touch because of its proximity to the surface of the skin we also have the dermal papillae those ridges of tissue which push up into the epidermis now underneath that is the reticular layer made out of dense irregular connective tissue as we look at the slide over here the collagen fibers are going in every which direction that helps it resist stresses from multiple directions and gives it strength embedded into the reticular layer we're going to find lamelated or pacinian corpuscles these sensory structures require a greater stimulus to get them to fire off than our tactile corpuscles so these are going to respond to deep pressure and vibrations here we have our arterials and remember they branch off with slightly smaller vessels which turn into capillary beds and these capillary beds in the papillary layer will then provide nutrients to the avascular epidermis one last thing just so that you can have something to hang on to with the reticular layer most of us own leather goods or leather clothing what is leather made from leather is actually the refined reticular layer from whatever animal that leather comes from on this slide i'd like to talk about fingerprints that's the whole basics of it so skin markings small visible lines in the epidermis created by the interaction between the dermis and the epidermis so remember those dermal papillae those ridges which come up in the papillary layer they actually create epidermal ridges which enhance the gripping ability of hands and feet so epidermal ridges occur in characteristic patterns the sweat pores leave a thin film or a fingerprint on things touched with the fingers so here's the slide that shows you what creates a fingerprint down here we have our dermal ridges those places that push up from the uh papillary layer and when they push up it's going to create an epidermal ridge a ridge on the surface of the skin so the results look like this on your fingertips these are your fingerprints the sweat pores as you release sweat is going to create a film so that whenever a person who is not wearing gloves touches a smooth flat surface it's going to leave an imprint of these fingerprints and these are unique to each individual person the last type of skin marking i'd like to discuss are called cleavage lines and they're found in the reticular layer now what a cleavage line is are lines of tension in the skin which exist in the reticular layer this has clinical significance for anyone who is making an incision on the skin if you or the physician cut with the tension lines that person is going to more likely heal faster and with less scarring as opposed to if you cut across or perpendicular to the tension lines this incision is more likely to heal slowly and have a tendency to scar now this should make sense to you because most of us have seen people who have had a c-section and most of the people who get cut for a c-section it's below the belly button and it kind of goes in a quarter moon shape like that and now you kind of understand why because that physician who did the c-section is cutting with the cleavage lines review questions for module 5.3 the papillary layer is made up of areolar tissue number two what characteristic does the dense irregular connective tissue impart to the reticular layer it imparts strength three what structures create a fingerprint the dermal ridges or dermal papillae create epidermal ridges which create the fingerprint but it all starts with those dermal papillae number four what is the clinical significance of cleavage lines if a practitioner cuts with the cleavage lines it is more likely that that incision will heal faster and with less scarring than if they cut across the cleavage lines next module 5.4 this is going to be very short let's talk about skin pigmentation so there are basically three pigments which can be found in any quantity in the skin the most important for skin color is determined by melanin that which we've already spoke and depending upon the color of melanin that you make whether it's yellow brown red brown or black that helps to determine your skin color so this is the most important skin pigment for determining skin color people can also find small amounts of keratin in their skin acting as a pigment so what is carotene a yellow orange pigment found in food items such as egg yolks and orange vegetables such as carrots and squash if you've ever met a child an infant who is finicky about their vegetables and will only eat carrots or only eats orange squash then their skin can actually take on an orange pigmentation and last of all hemoglobin found in our blood so that can provide skin with a reddish or a pink hue when you have increased blood flow in the dermis so this coloration will come and go depending upon activity level let's talk about how we can use skin color as a diagnostic tool so color changes associated with the amount of blood flow in the dermis can be useful in diagnosing disease so the first term erythema erythrocytes remember red blood cells so erythema indicates increased blood flow and it turns the skin more reddish or more pinkish that is a normal response to exercise so that's not really needed for a diagnostic tool although you notice if anybody gets on a stair climber on a treadmill their face usually turns kind of reddish other conditions that cause erythema include trauma road rash you fell down and skinned yourself on on the road on the asphalt fever or infection so these would be more important as a diagnostic tool pallor is the opposite of erythema so power is decreased blood flow and it's going to make the skin more pale that's a normal response when the body is trying to conserve heat when you're cold or during the fight or flight if you are scared to death that blood flow will go to your core and it's going to leave you looking very pasty and the last is called cyanosis so what color is cyanosis your skin takes on a faint bluish hue so that's a sign that somebody needs immediate attention because it's caused by a lack of oxygen in the blood so normal blood oxygen saturation is around 94 95 96 percent saturation with oxygen when that drops down to 75 to 80 percent that person is going to start taking on a bluish hue and that means that they need immediate attention