Anatomy, Blood, Skin, Tissues and Bone. Flashcards
What is the function of desmosomes?
Provide a strong bond between adjacent epithelial cells.
What is the function of cilia?
Provide a mechanism for movement of material over the surface of epithelia.
What is the function of hemidesmosomes?
Attach epithelial cells to the basement membrane.
Describe stratified epithelia.
They have more than one layer of cells.
What is the average circulating volume of blood in a typical adult male?
5 litres
1L lungs, 3L systemic venous circulation, 1L heart and arterial circulation
List the main functions of blood.
- carriage of physiologically active compounds
- clothing
- defense
- carriage of gases
- thermoregulation
- maintenance of ECF pH
Describe the composition of plasma.
Plasma proteins and interstitial fluid.
What are the main types of plasma proteins?
Albumin (60%), Globulin (38%), Fibrinogen and clotting factors (2%)
What is the function of albumin?
Generates colloid pressure, transport steroids, fats and vitamins, buffers H+ ions.
What is oncotic pressure generated by?
Plasma proteins
What is the average measurement of oncotic pressure?
approx 25mmHg
Define oncotic/colloid somatic pressure.
A form of osmotic pressure exerted by proteins, notably albumin, in a blood vessel’s plasma that usually tends to pull water into the circulatory system.
What is the opposing force of oncotic pressure?
Hydrostatic pressure
The net movement of fluid between capillary and interstitial space is subject to two forces. What are they?
- Capillary Hydrostatic pressure (favours movement out)
2. Plasma protein concentration (favours movement into capillaries)
What is the normal circulating level of WBCs?
1x10^10/litre
What is the lifespan of a RBC?
120 days
Describe the structure of a RBC.
Flexible, bi-concave, non-nucleated, packed with Hb
How long is the delay between erythropoietin rise to increase in RBCs?
2-3 days
Basal levels of erythrpoeitin are always circling. When is it released?
When O2 delivery to kidney fails due to cardiac dysfunction, haemorrhage, anaemia and lung disease
What is the function of erythropoietin?
Stimulates pluripotent stem cells to produce erythroblasts (immature RBC)
What are the five main types of WBC?
Monocytes, Neutophils, Eosinophils, Lymphocytes
What are the most abundant WBC?
Neutrophils (68%)
What are the least abundant WBCs?
Basophils
What WBCs rise following an allergic response and parasitic infections?
Eosinophils
Discuss monocytes.
After 72 hours in circulation, migrate to CT where they become macrophages and live for 3 months.
Compare monocyte and macrophage.
Monocyte = macrophage precursor, in circulation for 72 hours. Macrophage = In connective tissue for 3 months, phagocytosis
What controls WBC formation?
Leukopoiesis (more complex than erythropoiesis)
What controls leukopoiesis?
Cytokines (released from endothelial cells, fibroblasts and/or mature WBCs):
- Colony stimulating factors
- Interleukins
What type of WBC increases in response to bacterial infections?
Neutrophils
What type of WBC increases in response to viral infections?
Lymphocytes
What are the functions of platelets?
Adhere to damaged vessel walls and exposed connective tissue to form scaffolds and clots.
What is the structure of platelets?
Membrane bound cell fragments from cytoplasm of megakaryocytic from bone marrow.
What is the life-span of platelets?
10 days
What is the formation of platelets governed by?
Thrombopoietin stimulating bone marrow
Define haematocrit.
The percentage of RBCs as % of whole blood.
When does haematocrit increase?
- Heart and lung disease
- At altitude
What are the normal levels of haematocrit?
Male = 40-54% Female = 37-47%
Define viscosity.
How thick/sticky blood is.
What is the viscosity of plasma and whole blood in relation to water?
Plasma = 1.8 x thicker than water
Whole blood = 3.4 x thicker than water
In what circumstance will the viscosity of blood and plasma increase?
- Increase in haematocrit
- Decrease in temperature
- Decrease in flow rate
What is the largest organ in the human body?
The integumentary system.
What are the four tissues that make up skin?
- Epithelium
- Connective tissue
- Muscle
- Nerve
Describe the layers of skin.
- Epidermis
- Dermis (papillary and reticular layers)
- Hypodermis
Describe the epidermis.
- Epithelium
- Forms boundaries between internal and external compartments.
- Prevents water loss by evaporation.
Describe the dermis.
- Connective tissue
- Give structural strength
- Reduces risk of external injury, maintains epidermis by blood flow, permits body cooling, immune surveillance etc…
Describe the hypodermis.
- Adipose (fatty) connective tissue layer beneath the skin.
What is the function of superficial or subcutaneous tissue in skin?
Anchors skin to underlying structures.
Define keratinisation.
Organic process whereby keratin is deposited in cells, these become horny as in dead skin, nails and hair.
What type of epithelium is found in skin?
Stratified squamous keratinising epithelium.
What is psoriasis?
Autoimmune disorder affecting keratinisation
At what layer of the skin does stem cell division take place?
Stratum basale.
At what layer of the skin are dead cells sloughed off?
Stratum corneum
What are the five layers of the skin from top to bottom?
- Stratum corneum
- Stratum lucid
- Stratum granulosum
- Stratum spinous
- Stratum basale
CLGSB (Caitlin Likes Grapes and Strawberries)
What are the four cell types found in the skin?
Keratinocytes, Melanocytes, Langerhans cells, Merkel cells.
Describe the organisation of connective tissue in the dermis.
- Papillary layer
2. Reticular layer
Describe the papillary layer of the dermis.
- Loose CT
- Irregular interface with epithelium
- Cellular e.g macrophages
- Blood vessels
- Nerve endings - sense organ
Describe the reticular layer of the dermis.
- dense irregular CT
- collagen bundles in 3 planes
- elastic fibres (loss of elasticity in old age)
identify the accessory structures of the skin.
Hair, nails, sweat glands
Describe the structure and function of hair.
Hair follicle = hair + sheath(s), arrestor pilling muscles, sebaceous gland
Function = thermoregulation
Describe the structure and function of nails.
Hard keratin with same four layers as epidermis (nail plate is analogous to stratum corneum)
What are the eponycheum and hyponycheum?
Parts of nail (eponycheum is closest to cuticle)
Describe the sweat glands.Apocrine
- Sebaceous (hair follicles - sebum)
- Apocrine (axilla, protein rich)
- Eccrine
What are eccrine glands?
- simple tubular glands
- coiled and straight duct located in the dermis.
- spiral channel in epidermis