A&P - Blood & Integumentary System Flashcards
Blood is what type of tissue?
connective
After a sample of blood has been centrifuged, what components (and their percentages) would you find in a hematocrit?
plasma - 55% of total blood volume
formed elements - 45% of total blood volume
buffy coat
Blood is what percentage of total body weight?
8%
When separated from blood, what does plasma look like and what is it composed of?
straw colour
- about 90-91% water, 10% solutes (7% proteins, 2% other solutes)
Describe formed elements.
Term used to designate various kinds of blood cells and cell fragments typically found in blood (i.e. platelets, RBCs, WBCs)
What are the 4 groups of proteins found in plasma?
albumins 57%
globulins 38%
fibrinogen 4%
prothrombin 1%
True or False: Plasma is what one of three major body fluids.
True (besides interstitial fluid and intracellular fluid)
Which of the following are true statements regarding the function of blood?
1) picks up and delivers food and oxygen, and drops off waste
2) transports various substances (hormones, enzymes, buffers, etc.)
3) heat regulation
4) a + b only
5) all of the above
all of the above
A paramedic is describing why blood is the “keystone” of the body’s heat regulating mechanism. What properties allow for blood tissue to be involved in this function?
properties of high specific heat and conductivity which allow for absorption of lots of heat without big increases in own temp (so it keeps the internal temp in a relatively normal and functional range); also able to bring the heat from the core to the body surface
When a sample of blood is centrifuged, what components would you find at the top vs bottom of the test tube?
plasma (top), formed elements (bottom), buffy coat (middle)
Which of the following solutes are found in the plasma? Select all that apply.
1) Ions
2) Nutrients (glucose, lipids, proteins)
3) Waste products (urea, lactate, creatinine)
4) Gases (CO2, O2)
5) Regulatory Substances (hormones, enzymes)
ALL OF THEM
Solutes (aside from proteins) make up ___% of plasma
2
How is blood serum prepared?
Collect whole blood and allow blood to clot - will separate into serum (which is remaining liquid without blood cells and clotting elements) and clot (at the bottom of test tube - blood cells enmeshed in fibrin)
What is the difference between blood plasma and serum?
Plasma and serum both come from liquid portion of blood, however plasma is unclotted blood and still contains clotting factors. Serum is separated from clotting factors and is a pale yellow liquid that remains after the clot forms.
What constitutes buffy coat?
leukocytes (WBCs) and platelets
Globulins are essential in what kind of mechanisms?
immunity
Fibrinogens and prothrombins are involved in what kinds of mechanisms?
blood clotting
Where in the body are plasma proteins synthesized?
liver cells
What are the three main types of formed elements?
RBCs, WBCs, and platelets
An alternate name for platelets is ___________.
Thrombocytes
What are the two groups of leukocytes?
Granulocytes (have stained granules in cytoplasm) and agranulocytes (do not have stained granules in cytoplasm)
What are the three categories of granulocytes?
neutrophils, eosinophils, basophils
What are the two categories of agranulocytes?
lymphocytes, monocytes
Define: hematopoiesis
formation of new blood cells
What are the two types of tissues that produce blood cells?
- myeloid (aka red bone marrow)
- lymphoid
Where is myeloid tissue found in the body and what types of blood cells do they form?
Found in: sternum, ribs, hip bones (less in vertebrae, clavicle, cranial bones)
Produce: all blood cells EXCEPT lymphocytes
Where is lymphoid tissue found in the body and what types of blood cells do they form?
Found in: lymph nodes, thymus, spleen
Produce: lymphocytes
The life span of a red blood cell is approximately ____ days
105-120 days (or ~ 4 months)
The life span of a granulocyte is approximately _______ while life span of an agranulocyte is __________.
few days; 6+ months
In females, blood volume is typically _____ L while in males it is typically _____ L.
females: 4-5
males: 5-6
What factors affect blood volume?
- gender
- age
- body composition (i.e. fat content)
- method of measurement
Comparing an elderly person to a young male, who would have a greater blood volume? Why?
Young male would have greater blood volume because normal aging causes a reduction in total body water (which means less fluid in system/blood stream, less blood volume).
What methods are used to determine an individual’s blood volume?
Direct: complete removal of all blood in experimental animal
Indirect: tagging RBCs/plasma components with known amounts of radioisotopes and then measuring concentration of those radioisotopes after uniform distribution in the blood
1 unit of blood is approximately ____ L. It is ____ % of total blood volume.
0.45L; 10% of total blood volume
Blood volume varies inversely with what?
Amount of excess body fat (so the less fat, the more blood volume)
Comparing a female and male of the same age, one can assume that the ______ has a greater blood volume. Why?
Male; females typically have more fat in their body composition therefore have less blood volume
Define: hematocrit (aka packed cell volume or Hct)
the volume % of RBC in total volume of blood
What is the average Hct in males and females?
Males: 45% (normal range: 40-54%)
Females: 42% (normal range (38-47%)
A Hct of 35% would indicate what condition?
Anemia
A Hct of 56% would indicate what condition?
polycythemia
Healthy individuals often have elevated RBC count and Hct due to living/working in high altitudes. This condition is known as:
physiological polycythemia
If an individual is dehydrated, their Hct would likely (increase/decrease/stay the same).
Increase; because if plasma volume goes down, there is the still same number of RBCs therefore RBCs take up a greater % of total blood
A hematocrit of 40% would show what ratio of RBC and plasma?
40% RBC, 60% plasma
Primary component of RBC is:
hemoglobin
Looking at a RBC under the microscope, what does it look like? What advantages does this shape have for RBCs?
Biconcave disks (which allow increased surface area relative to its volume) & reduces cell spinning from blood flow turbulence
The flattened shape of an RBC also allows interior Hb to be close to plasma membrane for efficient gas exchange
True or false: Mature RBCs have the components of a typical cell (i.e. nucleus, ribosome, mitochondria)
False
Spectrin inside RBC serves what purpose?
Spectrin creates stretchable fibers in cell cytoskeleton that allow for RBC to be flexible and change forms when under mechanical shearing and bursting strains going through the capillary system
There are approximately _____ RBCs/mm^3 of blood in males and __________ RBCs/mm^3 of blood in females
5.5 million; 4.8 million
Males have more RBCs than females due to what?
stimulating effect of testosterone on RBC production
One Hb molecule can carry ___ molecules of oxygen.
4
Which cells carry oxygen? (not RBC but a type of RBC)
oxyhemoglobin??????????????? idk gerry phased this question weird
Describe the components within a Hb molecule.
4 protein chains (globins) each bound to a heme group (red pigment); each heme group has one iron atom
Hb combined with carbon dioxide creates:
carboxyhemoglobin
What is the normal Hb count in (g of Hb/100mL of blood):
Males
Females
Males: 14-16g of Hb/100 mL
Females: 12-14g of Hb/100 mL
A patient completed bloodwork and was told his Hb is less 10g/100 mL of blood. The doctor would likely describe this condition as:
anemia
What is erythropoiesis?
The production of red blood cells
Heme is broken down to what pigment?
bilirubin
Describe the process of erythropoiesis.
1) Starts as hematocytoblast in red bone marrow
2) proerythroblast - earliest precursor cell - where differentation starts
3) mitosis occurs which then produces basophilic erythroblast
4) further division produces polychromatic erythroblast (which produces Hb)
5) cell loses nuclei - becomes reticulocyte
6) reticulocyte released into circulation and loses reticulum - becomes erythrocyte
How does the body maintain homeostasis when blood O2 reaching tissues decreases?
oxygen deficiency stimulates secretion of erythropoietin (EPO) from the kidneys which stimulate bone marrow to accelerate RBC production
How are RBCs destroyed when they approach the end of their life span?
Aged RBCs undergo phagocytosis by macrophage cells in liver and spleen blood vessels
What is released as a result of breakdown of RBCs?
1) amino acids (from globin part of Hb) - recycled for new protein making
2) bilirubin - transported to liver to be excreted via bile and then feces
3) iron - returned to bone marrow to be used in making new hemoglobin
Define blood types
Refers to the type of cell markers/antigens present on the RBC membranes
What is the difference between agglutinins and agglutinogens?
Agglutinins: antibodies in plasma (generally fight against antigens)
Agglutinogens: blood antigens or foreign substances that stimulate the making of agglutinins
A patient was recently a recipient of a blood transfusion, however began to complain of fever, difficulty breathing, and had pink urine. He is suspected to be suffering from what condition?
1) melanoma
2) transfusion reaction
3) hypoxic injury
4) polycythemia
2) transfusion reaction
What happens when agglutinogens and agglutinins combine and react with each other?
agglutination (RBCs clumping or sticking together)
What is transfusion reaction?
When agglutination of donor and recipient blood occurs; antibodies attack donor’s RBCs which break down and released - may cause overload of kidney and cause kidney failure
What lab tests are done to reduce/eliminate risk of transfusion reaction?
1) cross-matching
2) blood typing
What are the 4 ABO blood types/groups? Identify the presence/absence of antigens for each of these groups
A - antigen A on RBCs; anti-B antibody in plasma
B - antigen B on RBCs; anti-A antibody in plasma
AB - antigen A and B on RBCs, neither anti-A or anti-B antibodies (universal recipient)
O - neither antigen A or B on RBCs, both anti-A and anti-B antibodies present (universal donor)
What determines if someone has Rh+ or Rh- blood?
- Rh+ blood has Rh antigen present on its RBC
- no Rh antigen in Rh- blood
A patient who is Rh-negative was found to have anti-Rh antibodies in her blood? What are two ways in which this could have occurred?
1) blood transfusion (Rh+ RBCs have entered bloodstream)
2) pregnancy
A pregnant lady who has Rh- blood found that agglutination has occurred in her second child. This condition is also known as what, and how did this occur?
Condition: Erythroblastosis fetalis
How it happens:
1) Rh- mom has Rh+ baby (potentially Rh+ from dad)
2) Baby’s RBCs cross over to mom’s, mixes with the Rh-
3) Baby’s Rh+ RBC is seen as a threat since it’s a foreign object not recognized by the mom’s immune system – anti-Rh antibodies made
4) If mom’s second baby is Rh+, antibodies enter baby’s blood supply and cause agglutination of RBCs with Rh antigen.
A patient with A+ blood can give to who and receive from who?
Give: A+ (same blood type), AB+ (no antibodies)
Receive from: A+, A-, O+, O-
A patient with O+ blood can give to who and receive from who?
Give: O+, A+, AB+, B+
Receive from: O+, O-
A patient with B+ blood can give to who and receive from who?
Give: B+, AB+
Receive from: B+, B-, O+, O-
A patient with AB+ blood can give to who and receive from who?
Give: only to AB+
Receive from: Everyone (universal recipient)
A patient with A- blood can give to who and receive from who?
Give: A-, A+, AB-, AB+
Receive from: A-, O-
A patient with O- blood can give to who and receive from who?
Give: Everyone (universal donor)
Receive from: O-
A patient with B- blood can give to who and receive from who?
Give: B-, B+, AB+, AB-
Receive from: B-, O-
A patient with AB- blood can give to who and receive from who?
Give: AB-, AB+
Receive from: AB-, O-, A-, B-
Provide a general description of what leukocytes look like.
Transparent (due to no pigments), have nuclei, and generally larger than RBCs
The most common leukocyte in a normal blood sample is which of the following:
1) basophils
2) neutrophils
3) monocytes
4) lymphocytes
5) esoinophils
neutrophils (~65% of total WBC count in normal blood sample)
What is the function of neutrophils?
Cellular defence - phagocytosis of small pathogenic microorganisms; also have powerful lysosomes to destroy bacterial cells
What is diapedesis?
The movement of leukocytes migrating out of blood vessels (and entering tissue spaces to do their jobs and then re-entering back into blood vessels when done)
Neutrophils can undergo an event known as chemotaxis. What is meant by this?
The directed migration of neutrophils (or other phagocytic cells) in response to a chemical stimulus
- ex. bacterial infection leads to inflammatory response that causes release of chemicals from damaged cells –> attract neutrophils
Where are eosinophils commonly found, and what is their primary function?
Location: mucous membranes (lining of resp and GI tracts)
Function: CELLULAR DEFENSE
- some phagocytosis (but generally weak)
- Protection against infections caused by parasitic worms and involvement (release cell toxins)
- regulating allergic reactions/inflammatory responses
What is the function of basophils?
Secretes heparin (anticoagulant) and histamine (important in inflammatory response)
The largest leukocyte in a normal blood sample is which of the following:
1) basophils
2) neutrophils
3) monocytes
4) lymphocytes
5) esoinophils
monocytes
What is the function of monocytes?
Cellular defence - highly phagocytic and engulfs large bacterial organisms and viral-infected/cancerous cells
The smallest leukocyte in a normal blood sample is which of the following:
1) basophils
2) neutrophils
3) monocytes
4) lymphocytes
5) esoinophils
lymphocytes
which element of blood is an anticoagulant?
heparin
What are the three main types of lymphocytes? Provide the function for each.
1) NK cells - agents of innate immunity; responds to any kind of cell that is non-self
2) T lymphocytes - agents of adaptive immunity; directly attacks infected/cancerous cells
3) B lymphocyes - agents of adaptive immunity; makes antibodies against specific antigens and uses these antibodies to attack infected cells
Function in general: humoral defence - secretes antibodies to regulate immune system
A patient’s WBC count came back and results show he has less than normal range (5000-9000 leukocytes/1mm^3 blood). What is this condition called?
Leukopenia
A patient’s WBC count came back and results show his WBC to be greatly elevated than normal range (5000-9000 leukocytes/1mm^3 blood). What is this condition called?
leukocytosis
Which list of cells has the greatest power of phagocytosis?
1) monocytes, neutrophils
2) monocytes, eosinophils
3) basophils, neutrophils
4) lymphocytes, macrophages
1) monocytes and neutrophils`
Which WBC contains histamine?
basophils
Which WBC helps against parasitic worms?
eosinophils
How is a differential WBC count advantageous compared to a typical WBC count.
Differential WBC count provides % of each type of WBC in the total WBC count instead of the total number of all WBC present in a blood sample
What is the order of leukocytes (from greatest to least, in %) would you expect to find in a typical differential WBC count.
Neutrophils, lymphocytes, monocytes, eosinophils, monocytes
Mnemonic: Never Let Monkeys Eat Bananas.
To get a comprehensive result and interpretation of someone’s health based on their blood composition which of the following tests would be the MOST beneficial?
1) differential WBC count
2) centrifugation of blood sample
3) blood typing
4) complete blood count
5) erythrocyte sedimentation rate (ESR)
4) complete blood count
Platelets are also known as:
Thrombocytes
Describe the structure of thrombocytes.
Structure: small, nearly colourless; irregular spindles/oval disks
What are the three important physical properties that platelets have?
1) Agglutination (sticking to each other)
2) Adhesiveness (sticking to things)
3) aggregation (breaking into smaller/larger pieces)
vicky come back to this one bc gerry was confusing
Platelets play an important role in hemostasis, which means what?
Hemostasis is the process of reducing (slowing or stopping) bleeding from injury blood vessels
Secondary function of hemostasis: defence against infections - blood clotting to trap them to prevent invasion)
Average platelet count (per 1mm^3 of blood):
250 000/mm^3 of blood (normal range: 150 000 - 400 000)
What are the functions of platelets?
Hemostasis, blood coagulation, defence against bacterial attacks (secondary role)
Define: thrombopoiesis
formation of platelets
Describe the formation of platelets starting from precursor cell hematocytoblast
1) hematocytoblast differentiates into megakaryocte (a massive cell that is in red bone marrow, lungs, spleen; controlled by thrombopoietin)
2) turns into megakaryoblast
3) megakaryocyte membrane ruptures
4) platelets released
The average life span of a platelet is:
7 days
What are the three major phases of hemostasis?
1) vasoconstriction
2) platelet plug formation
3) blood clotting (coagulation)
How does vasoconstriction reduce blood loss in a damaged vessel, as part of hemostasis?
1) injury of a blood vessel causes smooth muscles to spasm (and release of hormone/regulatory molecules from platelets or damaged cells) leading to vasoconstriction
2) increased pressure leads to temporary closing of damaged vessel = reduce blood loss
vasoconstriction can also be from external pressure (direct pressure in tx) or skeletal muscles reflexively constricting - ALL lead to the same effect of closing off the blood vessel temporarily
How does a platelet plug work in regards to hemostasis?
Platelets are activated to release chem signals (to cause vasoconstriction) and adhere to damaged lining and to each other to FORM a platelet plug which stops blood flow (sticky platelets)
The formation of a platelet plug happens (seconds/minutes/hours/days) after an injury to a blood capillary.
seconds (1-5 sec after injury so she quick)
What is a blood clot made of?
a net of fibrin trapping RBCs creating a clot
What are the three stages of coagulation?
1) Stage 1: Activation pathway (intrinsic and extrinsic pathway)
2) Stage 2: Thrombin formation
3) Stage 3: Fibrin clot formation
What is the function of the activation pathway within the blood clotting mechanism?
Produce prothrombin activator
Briefly describe the formation of thrombin (Stage II of blood clotting mechanism).
Prothrombin activator producted from Stage I initiates the mechanism (with the presence of Ca2+) for prothrombin to convert to thrombin
Briefly describe the formation of fibrin (Stage III of blood clotting mechanism).
Thrombin acclerates this stage and allows for conversion of soluble fibrinogen to insoluble fibrin (with the presence of Ca2+)
- fibrin is then what traps the RBCs forming a clot
Why are adequate calcium levels required for blood clotting mechanism to occur?
Ca2+ acts as a cofactor for a lot of clotting factors involved in the clotting mechanism so you’re screwed if you don’t have it and you’ll likely just bleed to death (maybe not but likely just increased bleeding cause your blood can’t clot)
How can the body obtain vitamin K?
- External sources - foods
- from good bacteria in the intestine
A patient having increased bleeding tendencies and was recently told by his doctor that his bile ducts have been obstructed (obstructive jaundice). One can suspect that this patient is suffering from what?
Vitamin K deficiency (because bile is needed for vit. K to be absorbed, and vit. K is needed for synthesis of prothrombin and fibrinogen which is involved in blood clotting mechanism.
so basically if you don’t have bile, you can’t have vitamin K, which means clotting factors can’t be made so your blood clotting mechanism sucks, and you bleed more
Where is prothrombin and fibrinogen synthesized?
liver
After Martha’s baby was born, why did the doctor put a gauze dressing on the umbilical cord and give the baby a dose of vitamin K?
1) babies don’t have fully developed bacteria system that would typically synthesize vitamin K
2) so less vit. K means less clotting factors made
3) increased tendency to bleed (so gauze dressing needed as well as a shot of vit. K to promote blood clotting)
What is the difference between antiplatelet and anticoagulant drugs?
Antiplatelets: decrease tendency for platelets to become sticky and form aggregates
Anticoagulants: makes blood less likely to clot and increase ease of flow
Which of the following is not an anticoagulant?
1) aspirin
2) heparin
3) warfarin
4) Plavix
plavix
Treatment for venous thrombi would include (anticoagulant/antiplatelet) drugs.
anticoagulants - venous thrombi are usually fibrin and RBCs, so it makes sense to use drugs that slow down clotting
Treatment for arterial thrombi would include (anticoagulant/antiplatelet) drugs.
antiplatelets - arterial thrombi are mainly platelet aggregates so it makes sense to use drugs that decrease tendency for platelets to aggregate and continue to grow
A patient who is troubled by intravascular coagulation called thrombosis might be treated with what?
heparin
A patient has been experiencing cramp-like pain in his calves after walking. The doctor notes that the patient has been experiencing occasional arterial microvascular blockages by platelet plugs. This condition is know as what, and what is the doctor’s best course of treatment?
intermittent claudication; tx: antiplatelet drugs
Which WBCs play a role in prevention of clotting?
basophils
List three conditions that would oppose clot formation?
1) healthy endothelium/normal blood vessels - have smooth surface
2) antithrombins - oppose/inactivate thrombin so fibrin cannot be formed (heparin, warfarin)
3) citrates - prevents donor blood from clotting before transfusion
List three conditions that would hasten clotting?
1) rough spots in endothelium (like plaque)
2) abnormally slow blood flow (ex. arteriosclerosis may lead to thrombosis)
3) body immobility: if you sit all day, blood flow slows down which may lead to thrombosis
How is clot formation a positive feedback loop? (*clarfication: textbook used this term but I do not believe they were talking about “positive feedback mechanism”)
once the clot forms, it grows. platelets stuck in fibrin activate and release more thromboplastin which causes more clotting and platelets being stuck
List 5 clinical methods to hasten clotting.
1) Apply rough surface
2) squeezing tissues around cut vessel (constriction)
3) purified thrombin
4) cold compress (causes vasoconstriction)
5) hemostatic materials
The physiological mechanism that dissolves clots is known as
fibrinolysis
True or false: Clot formation and fibrinolysis go on continuously.
True - working at the same rate to form and break up clots
How does the fibrinolysis mechanism work?
1) various substances released from cells of damaged tissue convert plasminogen to plasmin
2) plasmin hydrolyzes fibrin strands and dissolves the clot
What is the clinical significance of understanding the mechanism for fibrinolysis?
Can inject enzymes that generate plasmin into patients as early treatment/prevention for MI’s and stroke
Define anemia
A group of different conditions caused by the inability of blood to carry sufficient oxygen to body cells (can be due to inadequate number of RBCs, or deficiency of oxygen-carrying Hb)
A patient completed a complete blood count at the doctor’s office and was told his results indicate the following: low RBC count, WBC count, and platelet count. The patient also presents with significant fatigue, frequent ecchymosis, and has a history of frequent infections recently. The doctor indicates that this is mostly due to destruction of bone marrow. What condition is this patient likely suffering from?
Aplastic anemia
A patient completed an complete blood count at the doctor’s office and was told his results indicate the following: low RBC count, WBC count, and platelet count. The doctor indicates that this is mostly due to destruction of bone marrow. What is the typical treatment for this patient?
Bone marrow transplant
Pernicious anemia may occur because of a lack of which vitamin?
Vitamin B12 (could be due to inadequate diet intake OR if stomach lining doesn’t produce intrinsic factor that allows for B12 absorption)
Why would a patient with a vitamin B12 deficiency be anemic (low RBC count)?
vitamin B12 is used in formation of new RBCs in bone marrow
Folate deficiency anemia causes a low RBC count due to deficiency in what vitamin?
B9 (folic acid)
hyperchromic vs hypochromic
hyperchromic: refers to RBC having abnormally high Hb content
hypochromic: refers to RBC having abnormally low Hb content
What is hemolytic anemia?
a variety of inherited blood disorders characterized by abnormal types of Hb
“Honeycomb” or “punched-out” appearance of bones caused by defective antibodies from plasma cells is classic signs of what condition?
multiple myeloma
Define leukemia
blood cancers affecting the WBCs
Leukemia is associated with marked (leukocytosis/leukopenia).
leukocytosis (elevated WBC count)
A patient presents with fever, sore throat, rash, severe fatigue, and enlarged lymph nodes and spleen. This patient is likely suffering from what condition?
infectious mononucleosis (aka “mono”)
Difference between thrombus and embolus
Thrombus: clot formed in one place (condition is called thrombosis)
Embolus: clot dislodges and is flowing through bloodstream (condition is called embolism)
A patient is highly susceptible to bleeding out due to their body’s inability to form clots (due to failure to produce plasma proteins). This condition is known as:
Hemophilia
The condition in which you have a low blood platelet count is called what?
Thrombocytopenia
In the average adult, the skin size is approximately 1.6-1.9m^2 Convert skin surface size to square feet (m2 to sq. ft).
17-20 sq feet
What is the term we use to describe skin and appendages?
integumentary system
What are the two layers of skin?
1) epidermis - superficial, thinner layer
2) dermis - deeper, thicker layer
The vascular supply lies in which part of the skin?
Dermis (epidermis is avascular)
The area where the cells of the epidermis meet the connective tissue cells of the dermis is known as what?
dermoepidermal junction (DEJ)
Describe what thick skin (of epidermis) looks like.
- rigid surface with no hair
- contains all 5 layers of the epidermis
- has friction ridges
Where is thick skin found?
palms, fingertips, soles of feet, and other areas subject to friction
Where is thin skin found?
most of body surface except palms, fingertips, soles of feet, and high-friction areas
Describe the structure and function of friction ridges.
Structure: underlying dermal papillae raised into curving parallel epidermal ridges (forms fingerprints, foot prints)
Function: allows manipulation (for hands), slip resistance (for feet); sensory aids that amplify vibrations after touching surfaces
The regulated response of thick skin getting wrinkly when soaked in water provides what function?
Increased grip ability to surfaces
Describe what thin skin (of epidermis) looks like.
- has hair and smooth surface
- has irregular grooves
- may not have all 5 layers of epidermis
90% of epidermal cells are made of what type of epithelial cells?
keratinocytes
What do keratinocytes do in the epidermis?
They form the principle structural element of outer skin.
Starts in the deepest layer of the epidermis and are pushed upwards and filled with keratin. Eventually become corneocytes after dying and fully keratinized
What do melanocytes do in the epidermis?
- contributes coloured pigments to skin
- reduces the amount of UV light that can penetrate into deeper layers of skin
The acquired condition that results in loss of pigment in certain areas of skin (i.e. melanocytes present but no pigment production) is known as what?
vitiligo
What do dendritic cells/Langerhan cells do?
- involved with immunity (they are antigen-presenting cells meaning that they find antigens on bacteria and present them to the immune system cells for recognition and destruction
What do tactile epithelial cells/Merkel cells do in the epidermis?
- connect sensory nerve ending to form structures that function as light touch receptors
From deepest to most superficial, list the layers of the epidermis
Stratum:
1) Basale
2) spinosum
3) granulosum
4) lucidum
5) corneum
The superficial outer layer is stratum ___________.
corneum
Process of surface keratin starts in which layer of the epidermis?
stratum granulosum
What area of the body would you find especially thick stratum corneum?
palms, fingertips, soles of feet, and other areas subject to friction
Cells start to degenerate at which layer of the epidermis?
stratum granulosum
The only layer of cells in the epidermis that undergo mitosis is:
stratum basale
What is the function of glycophospholipids in the stratum corneum?
Cements keratin fibers into strong, waterproof barrier in the superficial layer of skin
Define keratinization
The process by which cells in this layer are formed from deeper layers and then filled with keratin and moved to the surface
A patient presents with significant thickening of the stratum corneum. On examination, the skin is dry, scaly, inelastic, and has fissures. This patient may be suffering from a condition known as:
hyperkeratosis
Which layer of the epidermis has a translucent quality and not visible in thin skin?
stratum lucidum
What is the most important function of skin?
protection
The regeneration time of new epidermal cells (from basal layer to the surface) takes approximately ____ days.
35
How are calluses formed?
When prolonged abrasion occurs with a shortened turnover time for cells resulting in abnormally thick stratum corneum
What area is known true skin?
dermis (aka corium)
What are the two layers of the dermis?
1) papillary layer
2) reticular layer
Papillary layer of the dermis is _____ (thin/thick) while the reticular layer is ______ (thin/thick)
thin; thick
What is the function of the dermis?
1) protection against mechanical injury/compression (contains skin’s mechanical strength)
2) reservoir storage area for water and electrolytes
3) processing sensory information (pain, pressure, touch, temperature)
Projections (known as dermal papillae) in the papillary layer of the dermis serve what function?
increase surface area for DEJ to strongly bind epidermis and dermis layers (rough surfaces hold better than smooth surfaces)
Touch and other sensory receptors are located in which layer of the dermis?
papillary layer
some other sensory receptors found in reticular layer too but touch is in papillary
What is the function of the reticular layer of the dermis?
provides skin toughness (collagenous fibers) and ability for rebound (elastic fibers)
What are arrector pili muscles?
bundle of muscles attached to each hair follicle
Which muscle produces goose pimples?
arrector pili muscles
What are cleavage lines (Langer lines) in skin?
lines that indicate the orientation of underlying collagenous fibers
Why are cleavage lines clinically significant in wounds and surgical incisions?
If surgical lines are made parallel to cleavage lines, would will tend to heal much better (less likely to open, less noticeable scar)
If surgical lines are made at right angles to these cleavage lines , stress tends to pull on the cut edges which make them more likely to open
Overstretched elastic fibers in dermis (such as in pregnancy or morbidly obese patients), fibers may eventually weaken or tear. What is the likely to appear on the skin as a result of this overstretching?
stretch marks
What is the hypodermis?
A subcutaneous layer that lies below the dermis, connects skin with underlying tissues
Why are subcutaneous injections preferred (i.e. why is it advantageous to inject material into the level of the hypodermis)?
Because it’s got porous spongey texture, has major blood vessels.
Ideal site for rapid and relatively pain-free absorption of injected materials
What is the main determinant of skin colour?
quantity and type of melanin deposited in cells of epidermis by melanocytes
What are the two groups of melanin?
1) eumelanin - very dark brown to black
2) pheomelanin - lighter reddish/orange colour
Dark skinned and dark haired people have large quantities of what type of melanin?
eumelanin
Individuals with light-coloured skin, red/orange freckles, and red hair have large quantities of what type of melanin?
pheomelanin
How does melanin production occur?
1) In melanocytes, pigment granules are produced (regulated by tyrosinase) and then released in melanosomes
2) melanosomes transferred to nearby keratinocytes where melanins form a light-absorbing protective cap over nucleus
True or false: genes have primary control over melanin production
True
Albinism occurs due to the absence of _______ due to a genetic mutation, resulting in melanocytes not being able to form melanin.
tyrosinase
The papillary layer of the dermis does what?
increase surface area of the DEJ to better bind skin layers together; also has dermal ridges that allow for gripping/using tools, detecting surface textures, and slip resistance
Sunlight (increases/decreases) melanin production. Why?
Increases; to increase nuclear cap formed by melanin which protects from UV radiation before DNA damage and skin cancer
Why are dark-skinned individuals at less risk of skin cancer than light-skinned individuals?
1) eumelanin absorbs more UV radiation than pheomelanin therefore less damage going through to cell nucleus
2) dark skin pigmentation also facilitates apoptosis of damaged cells therefore prevent cells from becoming cancerous)
What are age spots?
Excess melanin production from cumulative UV exposure
What is jaundice?
Yellow discolouring of the skin or sclera of the eye
What causes jaundice?
1) bile pigments buildup and cannot be eliminated by liver
2) in bebes, old RBCs with immature form of Hb are rapidly replaced by RBCs with mature form and bebe’s liver is too immature to handle remove of bile products
Why would a doctor use UV light in babies with jaundice?
UV light can break down pigments to promote recovery
What is lipofuscin?
a brown-yellow pigment that accumulates when epidermal cells age and stop undergoing mitosis (cause aged skin to look mottled and brown-yellow)
What causes the skin to look cyanotic?
When there is excess Hb that is low in oxygen and high in carbon dioxide (Hb changes to a deep maroon colour when low oxygenated and light reflection/diffusion creates bluish colour)
How is skin colour temporarily changed with volume of blood flowing through skin capillaries?
Vasodilation with lots of highly oxygenated Hb = red/flushed
vasoconstriction and decreased oxygenated Hb = less red/paler
A parent is informed that their child does not have the enzyme tyrosinase. In what will this result?
albinism
The brown pigment that is seen with bruises after RBCs have been broken down is known as:
hemosiderin
List 7 functions of the skin.
- Protection
- sensation
- growth
- synthesis of important cheimcals and hormones
- excretion
- temp regulation
- immunity
Which vitamins are absorbed through the skin?
A D E K
Protection is a function of the skin. How?
1) surface film/mechanical barrier (against microorganisms)
2) keratin (against dehydration)
3) melanins (against UV radiation)
4) tissue strength (against mechanical trauma)
Sensation is a function of the skin. How?
through somatosensory receptors, skin can sense pain, temperature, pressure, and touch
Growth is a function of the skin. How?
through elastic and recoil properties of skin and subcutaneous tissue
Skin has endocrine functions. How?
UV light activates precursor compound in skin cells to allow vitamin D production
Excretion is a function of the skin. How?
skin regulates sweat content and volume; excretes waste products
Immunity is a function of the skin and occurs how?
Attacking and destroying microorganisms. Epidermal dendritic cells along with helper T cells trigger helpful immune reactions.
Temperature regulation is a function of skin. How?
Regulates blood flow to skin and evaporation of sweat for heat loss/retention
Surface film on skin is composed of what?
residue, microbial cells, secretions from sweat and sebaceous glands, and epithelial cells (+ contents)
Provide 5 functions of surface film.
1) antibacterial and antifungal activity
2) lubrication
3) hydration of skin surface
4) buffering of caustic irritants
5) blockage of toxic agents
True or false: if there is too much melanin, the body cannot synthesize enough vitamin D for normal function
True (external source like vit D supplement required)
At what time of the day is our body temperature usually lowest?
Early morning (36.2 deg C)
At what time of the day is our body temperature usually highest?
Around late afternoon (up to 37.6 deg C)
Which part of body is the largest determinant of amount of heat production?
Muscles - very active tissue and large size
What are the 4 physical processes by which heat loss via skin can occur?
Evaporation, convection, radiation, conduction
Define heat loss via radiation.
Transfer of heat from surface of one object to another without actual direct contact (i.e. heat radiates FROM skin to cooler surfaces; heat radiates TO skin from warmer object)
Define heat loss via conduction.
Heat loss during direct contact with an object
Define heat loss via convection.
Heat loss from a surface by movement of heated air/fluid particles
Define heat loss via evaporation.
Heat loss through sweat turning into vapor (liquid to gas)
Describe the negative feedback mechanism of heat loss when someone is exercising.
1) Variable: exercise causes increase in internal temp
2) Sensor: temperature receptors in skin sense change in temp, sense information to integrator
3) Integrator: hypothalamus takes in information and compares to normal body temp and then sends signals out to effector
4) Effector: sweat glands (evaporation); blood vessels vasodilate (radiation)
Why does the same temperature seem hotter in humid climates?
In humid climates, the moisture content of the air is high to the point where it cannot take on anymore water so sweat doesn’t evaporate. Slows the evaporative process down and lessens the cooling result from it
Appendages of the skin include what?
hair, nails, and skin glands
What are the two primary layers of the hair follicle wall?
1) dermal root sheath
2) epithelial root sheath
How does a hair follicle develop?
Cells of germinal matrix undergo repeated mitosis and push upward in the follicle, become keratinized to form a hair
What are sebaceous glands?
glands that secrete sebum for hair and skin
What is the function of sebum?
- keeps hair supple and skin soft/pliant
- prevents excess water loss from epidermis
- has antifungal properties on skin surface
Nails are composed of what type of cell.
Heavily keratinized epidermal cells
True or False: Kids rely on increased blood flow to maintain normal temperatures in their bodies compared to adults.
True, they has less sweat glands than adults so less effective option of dissipating heat
Acne is caused by what?
overactive sebaceous glands that cause sebum/skin cells to block or cause inflammation to the sebaceous ducts
What are the three kinds of skin glands?
sweat glands, sebaceous glands, ceruminous glands
What are the two groups of sweat glands?
eccrine sweat glands
apocrine sweat glands
What is the waxy secretion in the ear called? What is its function.
cerumen (aka ear wax) - mixture of sebaceous and ceruminous glands
Function: protect ear canal from dehydration
Difference between eccrine and apocrine glands?
Eccrine - most numerous, all over body,
function: your typical production of sweat to eliminate waste, maintain body temp
Apocrine - concentrated in the armpits and groin, associated with hair follicles, and has odour due to bacterial decomposition
What are ceruminous glands?
modified apocrine sweat glands in the ear canal
Define dermatosis.
term used for any skin disorder
True or False: Children are more susceptible to skin infection due to lack of sebum on skin surface.
True
A young child presents with tons of blisters and yellowish crust around the mouth. Doctors diagnose this to be a bacterial infection (from streptococcus/staphylococcus) known as:
Impetigo
Define tinea and provide two examples of this condition.
General term for fungal infections of skin.
Ex. ringworm, jock itch, athlete’s foot
Large, inflamed pus-filled lesion caused by local staphylococcus infections of hair follicles describes what condition?
Boils/furuncles
Warts are caused by what virus and what is the typical tx?
papillomaviruses
tx: freezing and removing, drying it out, laser therapy, chemical applications
Severe itching can lead to raised red lesions (wheals). This condition is known as:
uticaria
The condition characterized by skin inflammation with silver coloured, scaly lesions (from excessive epithelial cell growth) is known as
psoriasis
Define scleroderma
autoimmune disease affecting blood vessels and connective tissues of the skin
The two most common forms of skin cancer are:
1) basal cell carcinoma
2) squamous cell carcinoma
What is the type of cancer associated with changes in a mole on the body?
melanoma
What increase in body temp would be by pyrogens?
fever/febrile state
Why would a patient experience chills during a febrile state?
pyrogens have caused the body’s “thermostat” to be set higher causing the need to warm up to new temp = chills
Define heat exhaustion.
Occurs when body loses large amounts of fluid from heat loss mechanisms
What are the S/S of heat exhaustion? and treatment?
S/S: dizziness, weakness, nausea, possible LOC, heat cramps
Tx: rest, cool environment, fluid replacement
Define heat stroke.
Occurs whe body is unable to maintain normal temp in an extremely warm environment.
What are the S/S of heat stroke? and treatment?
S/S: body temp > 41 deg C, tachycardic, headache, hot and dry skin, confusion, convulsions, LOC
Tx: body cooled and fluids replaced IMMEDIATELY
Define hypothermia.
Occurs when body is unable to maintain normal temp in an extremely cold environment.
What are the S/S of hypothermia? and treatment?
body temp < 35 deg C, shallow and slow respirations, faint and slow pulse
Tx: slowly warming the body
Define frostbite.
Local tissue damage (from ice cyrstal formation in tissues) due to extremely low temperatures. May lead to necrotic tissue or gangrene
Prognosis and treatment of burns depends on what two factors?
1) Severity of the burn (depth and extent)
2) Total area involved
Methods to estimate total body surface area burned include: (3)
1) Rule of palms - palm size of burn patient is 1% TBSA
2) Rule of nines
3) Lund-Browder charts (for children)
Deep vs. superficial burns.
Deep: burns that affect deep part of dermis and beyond
Superficial: everything above that^
Partial thickness burns include which of the following (choose all that apply):
1) first degree burn
2) second degree burn
3) third degree burn
4) fourth degree burn
first and second degree
Full thickness burns include which of the following (choose all that apply):
1) first degree burn
2) second degree burn
3) third degree burn
4) fourth degree burn
third and fourth degree
What are first degree burns and how are they characterized in the skin?
- Burns that affect just the epidermis (ex. typical sunburn)
- minor discomfort and reddening, no blistering and may peel in a couple days
What are second degree burns and how are they characterized in the skin?
- burns to deep epidermal layer and AT LEAST upper layers of dermis (so may go deeper)
- may damage skin glands
- S/S: blisters, severe pain, edema and swelling, scarring common
What are third degree burns and how are they characterized in the skin?
- both dermis and epidermis destroyed
- tissue death extends below hair follicles and skin galnds
- nerve ending destruction so can’t feel a thing
- may look whitened or charred, scarring occurs
What are fourth degree burns and how are they characterized in the skin?
- burn through basically everything down to the muscles, fascia and bone
- nerve ending destruction so no pain
Average normal adult red blood cell count for males and females:
Males: 5.5 mil/mm^3 blood
Females: 4.8 mil/mm^3 blood
