Tissue Flashcards
Epithelial
forms sheets of cells that cover surfaces or line the body cavities. All glands are made up of epithelial tissue.
Types of Epithelial
- covering and lining epithelium – forms the outer layer of the skin, covers the organs of the abdominal cavity and lines open cavities such as the stomach or lungs
- glandular epithelium – makes up the glands within the body.
3 Shapes of Epithelial
- Squamous (flat)
- Cuboidal (box)
- Columnar (pillar)
- Cuboidal (box)
2 arrangements of Epithelial cells
- Simple epithelium (single layer)
2. Stratified epithelium (layered)
Characteristics of epithelial cells
- they have polarity - an apical and a basal surface
- they have tight junctions and desmosomes to hold the cells together
- they are supported by connective tissue
- they are avascular and innervated (contain no blood vessels but are supplied by nerve fibers)
- they can regenerate (mitosis)
Functions of epithelial cells
- protection, barrier, sweeping
- exchange – diffusion, filtration, absorption
- secretion and excretion
- sensation
Glandular epithelium
epithelium has the specialised function of being able to secrete substances. These watery (aqueous) secretions also contain proteins and various other substances depending on the purpose eg saliva or hormones.
Endocrine Glandular Epithelium
glands are ductless glands which secrete hormones directly into the bloodstream.
Exocrine Glandular Epithelium
glands secrete their products through a duct to the external surface or into the respiratory, gastrointestinal or genitourinary tract. Secretions from exocrine glands include mucus, saliva, digestive juices and sweat.
Connective Tissue
supports, connects or separates different types of tissues and organs.
3 main components of connective tissue
- Fibre (elastic or collagen)
- Matrix or ground substance
- Cells (fibroblasts, adipocytes and leucocytes)
2 subdivides of connective tissue
- Connective tissue proper (loose or dense)
2. Special connective tissue (bone, cartilage or blood)
Characteristics of connective tissue
- a common origin (mesoderm)
- the cells are spread throughout the extracellular matrix
- a water base with adhesion proteins makes up the ground substance (matrix)
- there are more or fewer fibers (collagen, elastic and reticular) in the matrix
- they are more or less vascular
Functions of connective tissue
- binding
- support
- protection
- movement
- insulation
- transport
Nervous Tissue
main component of the nervous system and makes up the brain and spinal cord (central nervous system) as well as the peripheral nervous system.
Two types of cells in the nervous tissue
- neurons which are highly specialized cells that generate and conduct nerve impulses (messages).
- neuroglial cells make up the packing and supporting cells in the nervous system.
Characteristics of nervous tissue
- specialized structures (long axons) of the neurons to carry impulses
- polarised membranes to generate and conduct impulses
- excitability of the cells (responsiveness)
Function of nervous tissue
- integration and communication.
* regulates and controls bodily functions and activities.
Muscle Tissue
cells that are capable of contraction and this creates movement.
3 Types of muscle tissue
- Skeletal
- Cardiac
- Smooth
Skeletal muscle tissue
multinucleated and striated. Muscles have a superficial covering of connective tissue which extends and attach to bone (tendon). Inside the muscle are smaller muscle cell bundles (fasciculus) surrounded by perimysium.
Cardiac muscle tissue
only found in the heart and is responsible for the contraction of the heart. This pumping action allows blood to be circulated. The cardiac muscle functions spontaneously without tiring. The cardiac muscle cells are striated and branched with intercalated discs.
Smooth muscle tissue
uninucleated and non-striated. It functions spontaneously with long sustained contraction. Smooth muscle is found in the lining of blood vessels, urinary bladder, kidneys, oesophagus and small intestine.
Functions of muscle tissue
- movement or locomotion
- transport or movement
- heat production
- support
- shape or framework
