2 - Examining Cells & Tissues Flashcards
What are the 4 classifications of tissue?
- Epithelial
- Connective
- Muscle
- Nerve
What is epithelial tissue?
- Lines all the body surfaces and often surrounds other tissues
- Sometimes in clusters with other tissues (glands)
- At surfaces, always have a basement membrane
- Held together by strong anchoring proteins
What do epithelial cells often secrete from their apical surface? How does this benefit the cells?
Secretes sugars from the apical surface - called the glycocalyx
Attracts water to the cells to stop them drying out
What are the different types of connective tissue?
- Fibrous (dense) connective tissue
- Loose connective tissue
- Cartilage
- Adipose tissue
- Bone
- Blood
What is the main cell type in tendons and ligaments?
Fibroblasts
What is the main cell type in cartilage?
Chondrocytes
What are the main cell types in bone?
Osteocytes, osteoblasts and osteoclasts
What are the main products of cells in connective tissue?
- Fibres (many types)
- Ground substance
- Wax and gel-like materials
What are the connective tissue layers of a nerve and where are they found?
Epineurium - surrounds the whole nerve
Perineurium - surrounds nerve fascicles within the epineurium
Endoneurium - inside the nerve fascicles surrounding the neurones
What are the 3 types of muscle cell?
Which of these are striated?
- Skeletal (striated)
- Cardiac (striated)
- Smooth (non-striated)
What are the major functions of the muscles?
To contract!
- Movement
- Stability of whole body, organs and tissues
- Movement of tissue contents (e.g. peristalsis)
What is a minor function of muscle tissue?
To secrete hormones
- Natriuretic factors - produced by the heart to reduce water in the blood via kidneys
- Myostatins - control heart growth
What cell has the largest average volume?
The oocyte
What is the limit of resolution?
The smallest distance by which two objects can be separated and still be distinguishable as two objects.
Compared to a microscope, the naked eye cannot discern objects that are very close together, it is said to have a low ………… …………
Resolving power
Put these imaging techniques in order of resolving power (highest to lowest):
- scanning electron microscope
- light microscope
- transmission electron microscope
- naked eye
- Transmission electron microscope
- Scanning electron microscope
- Light microscope
- Naked eye
Which of the electron microscope or the light microscope has the largest field of view?
Light microscope
What is the magnification of a light microscope and an electron microscope?
Light - x600
EM - x500,000
What is the resolution of a light microscope and electron microscope?
Light - 0.25 μm
EM - 0.25 nm
What is the preparation process for electron microscopy?
- Fix with glutaraldehyde
- Embed in epoxy resin
- Stain with osmium tetroxide
- Cut with microtome (diamond knife)
Fixation and preservation of tissue for imaging prevents ……………
Putrefaction (rotting)
What is the thickness of tissue needed for light microscopy?
5 μm thick slices
For light microscopy, tissue is preserved in ……….., which is what?
Formalin
Formaldehyde in physiological saline.
Why is formaldehyde used in fixation?
Adds methyl groups and cross-links proteins to prevent degradation. Fixes proteins in their position.
