Tissue Structure, Histology, Integument Flashcards
When do cells differentiate?
As the body divides from a fertilized egg
What are the four kinds of tissue?
Epithelial, connective, muscle, neural
What is the definition of an organ? What is the definition of a tissue?
Organ: two or more types of cells working together to perform specific functions
Tissue: a group of similar cells (and their products) working together to perform specific functions (includes the extracellular material and fluid directly around them)
Epithelial locations
- covers exposed surfaces
- lines internal passageways and chambers
- forms secretory glands
Connective tissue functions
- fills internal spaces
- provides structural support
- stores energy
Muscle tissue functions
- contracts to produce movement
- includes skeletal muscle, cardiac muscle, and smooth muscle
Nervous tissue functions
- conducts electrical impulses
- carries information
Epithelial tissue functions
- provide physical protection
- controls permeability
- provides sensation
- produces specialized secretions
What are the three types of epithelia structure?
- Squamous
- Cuboidal
- Columnar
What kind of tissue is a gland made of?
Epithelial
What are the three kinds of glandular secretion?
- Merocrine: released by exocytosis from secretory vesicles (e.g. mucin)
- Apocrine: released by shedding apical part of cell and cytoplasm (e.g. milk production)
- Holocene: released by the entire cell bursting, releasing contents (e.g. sebum production)
What is connective tissue?
Definition: presence of extracellular protein fibres suspended in ground substance
What are the three main types of connective tissue?
Proper, fluid, and supporting
What are the two types of proper connective tissue?
Loose: areolar, adipose, reticular
Dense: regular, irregular, elastic
What are the two types of supporting connective tissue?
Cartilage: hyaline, elastic, fibrocartilage
Bone
What are some examples of extracellular fibres?
Elastin, collagen
What do tissue membranes consist of?
Epithelial + underlying connective tissue
What are the three layers of connective tissue?
Superficial, deep, subserous
What is another name for skin?
Cutaneous membrane
What makes up the integument? What is its primary function
Cutaneous membrane + accessory structures; first line of defence against the physical, chemical and biological environment
What are the functions of the integument?
- Barrier
- Synthesize vitamin D
- Sensory
- Regulate body temp
What is the hypodermis? Is it part of the integument?
Subcutaneous layer of tissue that is NOT part of the integument
What does the epidermis consist of?
Stratified squamous epithelium:
- Stratum corneum
- Stratum lucidum
- Stratum granulosum
- Stratum spinosum
- Stratum basale
What layer of epidermis do cells lose their nuclei and organelles?
Granulosum
What layer produces melanin and transfer them to keratinocytes?
Melanocytes within stratum basale via vesicle transportation
How does the skin prevent UV light from damaging cells?
Melanin absorbs UV photons— enters a high energy state that is not reactive, so it can later release the energy as heat
What does the dermis consist of?
- 2 layers of vascularized connective tissue, supporting cells for secondary functions
What are the two layers of dermis?
Stratum papillare, stratum reticulare
What is the the hypodermis often full of?
Adipocytes
What are the mechanisms of tissue repair in epidermis and dermis?
Epidermis: quickly, through proliferation of basal cells (divisions without daughter cells specializing as keratinocytes)
Dermis: granulation tissue, a mixture of dividing mesenchymal cells, fibroblasts and new blood vessels
What do myoepithelial cells do?
Epithelial derived cells with muscle like ability to contract, they surround glands
What is the sensor, integrator and effector in temperature regulation?
Sensor: temperature receptors in the skin and brain
Integrator: brain
Effector: sweat glands and smooth muscle in the walls of blood vessels
Where is vitamin D synthesized? What happens to it?
Stratum spinosum and basale
- vitamin D converts to calcitrol
What is the trade off between melanin and vitamin D synthesis?
If some UV reaches basal layers, vitamin D is synthesized. If a LOT of UV reaches basal layers, cellular damage increases
What are some effects of ageing on the integument?
- fewer melanocytes
- drier epidermis
- thinning epidermis
- decreased perspiration
- fewer active follicles
- diminished immune response
- thinning dermis
- reduced blood supply
- slower repair
