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| Question | Answer |
| What are the two types of epithelia? | 1. Covering and lining epithelia 2. Glandular epithelia |
| Examples of covering and lining epithelia are | - surface of the skin - eye and eyelids extending into the conjunctiva - lining of the bladder, blood vessels and digestive tract |
| Examples of glandular epithelia | - salivary glands - thyroid gland - lacrimal gland |
| What is the function of covering and lining epithelial tissue? | Controls permeability by: absorption, secretion, filtration, excretion |
| Examples of covering and lining epithelia in the eye | - skin of eyelids - conjunctiva - cornea (has an epithelium and endothelium) - iris, lens and retina - ducts of glands - blood vessels (endothelium) |
| Describe the apical surface of the epithelial tissue | - the upper surface, free - can have microvilli (e.g. intestinal lining) - can have cilia (e.g. lining of trachea) - proteins have a different function to those of the basal surface - projected exteriorly i.e. skin or internally to a body cavity i.e. GI tract |
| Describe the basal surface of the epithelial tissue | - basal surface is ATTACHED to underlying connective tissue via the basal lamina - basal lamina is a very thin non-cellular layer of glycoproteins and collagen fibres - contains proteins with a different function to the apical surface |
| True or false? Epithelial tissues have a high rate of regeneration | True! Stem cells in the basal layer are dividing rapidly to replace lost cells |
| What are the three basic types of membrane junctions? | 1. Tight junctions 2. Anchoring junctions 3. Gap junctions |
| What is the function of tight junctions/zonula occludens? | - prevent fluids and molecules from moving through the intercellular space - as they have to move through the epithelial cells and not around them - and thus the epithelial cells can control movement |
| What is an example of a tight junction in the eye and what is its function? | - in the retina there are VERY tight junctions in the epithelia and endothelia - function is to insulate the very sensitive nerve cells of the retina from other substances called the blood-retinal barrier |
| What is the function of the anchoring junction? | - also known as zonula adherens - designed to hold the epithelium together |
| What is the function of the gap junction? | channels exist between adjacent cells and allow ionic/chemical communication between the cells |
| A single layer epithelium is called? | Simple epithelium |
| An epithelium with two or more layers of cells is called? | Stratified epithelium |
| Describe squamous cells | - thin and flat - nucleus is flattened, thick and projected outwards |
| Describe cuboidal cells | - cube shaped - nucleus is round and centered in cell |
| Describe columnar cells | - tall and thin shape - nucleus is long and thin and located at the base of the cell |
| Examples of simple squamous epithelia | - where diffusion/absorption takes place i.e. inside cornea (endothelium) or alveoli of lung - where a slippery surface reduces friction e.g. lining blood vessels (endothelium) |
| Simple cuboidal epithelium | - functions include secretion and absorption - found in kidney tubules, ovary surface and ducts and secretory portions of small glands - also found in lens epithelium |
| Keratinised stratified squamous epithelium | - layer of dead cells are packed with a protein called keratin which is tough and water-resistant - found in dry locations e.g. skin surface |
| Non-keratinised stratified squamous epithelium | - forms moist linings of oral cavity, esophagus, cornea - resists abrasion but can dry out |
| Stratified cuboidal epithelia | - quite rare in the body - found in mammary glands and some sweat glands - typically only two cell layers thick |
| Stratified columnar epithelia | - found in CONJUNCTIVA, salivary glands and pancreas - two or more cell layers thick |
| What type of epithelia is located where the stressors are severe? | Stratified squamous epithelia are located where the stressors are severe |
| What are endocrine glands? | - ductless glands that create hormones and pass them on the lymph/blood vessels to carry to target organs - include pituitary gland, thyroid gland and adrenal gland |
| What are exocrine glands? | - secrete products into ducts - secretions are released onto body surfaces (skin) or into body cavities - e.g. lacrimal gland (tears), sweat gland (skin of eyelid), mucous gland, sebaceous gland (skin of eyelid) |
| What are Meibomian/Tarsal glands? | - large modified sebaceous glands - release an oily secretion - empties in the vicinity of eyelashes and contributes to tear film |
| What are the glands of Zeis? | - large modified sebaceous glands - release oily secretion at shafts of eyelashes |
| What are the glands of Moll? | - modified sweat glands - release sweat in the vicinity of the eyelashes |
| Goblet cells | - unicellular exocrine glands - found in conjunctiva - merocrine secretion mixes with water to form mucin - mucus is a lubricant and protective barrier from foreign particles and microorganisms |
| What does the merocrine mode of secretion involve? | - cells produce secretory granules/vesicles in large numbers - granules move to the apical surface of the membrane and fuse in exocytosis - this causes the release of secretory product onto the cell surface - cell remains intact and does no die |
| What does the holocrine mode of secretion involve? | - cells produce secretory granules until full - entire cell bursts - granules released into duct system - cell dies, cell division occurs and the dead cells are replaced with living cells |
| What type of secretion occurs in the Meibomian/Tarsal glands? | Holocrine secretion |
| All connective tissue contains? | - Specialised cells - Extracellular protein fibres - Fluid/ground substance |
| What are the extracellular proteins fibres? | - Collagen - strongest and most abundant - resistant to stretch - Elastin - long and thin - allow for stretch - Reticular - short and fine - only found in specialised areas |
| What is the purpose of ground substance/viscous fluid? | - the medium between which solutes/nutrients diffuse between blood capillaries and cells |
| What are the components of ground substance? | - interstitial fluid (filtrate of blood plasma) - adhesion proteins e.g. fibronectin - proteoglycans |
| What are some examples of connective tissue proper? | - Loose = areolar tissue, adipose tissue Dense - dense regular, dense irregular and elastic |
| What are some examples of supporting connective tissue? | - hyalin, elastic and fibrous cartilage - bone |
| What components make up the matrix of connective tissue? | - ground substance and extracellular fibres |
| What is the purpose of the fixed cells of the loose connective tissue? | - maintenance, repair and storage - remain stationary |
| What are some examples of fixed cells? | - melanocytes - fixed macrophages - mast cells - fibroblasts - adipocytes |
| What is the purpose of wandering cells of the loose connective tissue? | - move throughout the tissue - defend against pathogens (neutralise) - repair any damage being caused |
| What are some examples of wandering cells? | - plasma cells - free macrophages - mesenchymal cells - neutrophils - eosinophils - lymphocytes |
| What is the function of areolar tissue? | - wraps and cushions organs - its macrophages phagocytize bacteria - holds and conveys tissue fluid |
| Where is areolar tissue in the body? | - widely distributed under epithelia of body - forms lamina propria of mucous membranes - surrounds capillaries - packages organs |
| What is the function of adipose tissue? | - insulates against heat loss - provides reserve food fuel - supports and protects organs |
| Where is adipose tissue located in the body? | - under the skin in the hypodermis - around eyeballs - in abdomen - in breasts |
| What is the function of dense regular connective tissue? | - attaches muscles to bones or to other muscles - attaches bones to bones - withstands great high tensile stress - in one direction |
| Where is dense regular connective tissue in the body? | - tendons - most ligaments - aponeuroses |
| What is the function of dense irregular connective tissue? | - able to withstand tension exerted in many directions - provides structural strength |
| Where in the body is dense irregular connective tissue? | - fibrous capsules of organs and of joints - dermis of skin - submucosa of digestive tract |
| What are 5 functions of bone? | 1. Provide support for the body and attachment for soft tissues 2. Storage of mineral i.e. calcium and phosphate 3. Blood cell production in bone marrow 4. Protect delicate tissues and organs e.g. bone surrounding the eye 5. Move the body by acting as levers with the skeletal muscle |
| What are the 4 classifications of bone by shape? | 1. Long bone - longer than it is wide (fingers and toes) 2. Short bone - cube-shaped (wrists and ankles) and sesamoid (within tendons) 3. Flat bone - thin, flat and slightly curved (e.g. sternum, ribs and cranial bones) 4. Irregular bones - complicated shapes (vertebrate and facial bones) |
| What is the outer surface of bone and how many layer does it have? | The periosteum - 2 layers - the outer fibrous layer and the inner cellular layer |
| What are the components of the outer fibrous layer of the periosteum? | - composed of dense irregular connective tissue - tightly fixed to underlying bone - attachment point for tendons and ligaments |
| What are the components for the inner cellular/osteogenic layer of the periosteum? | - formed by cells including: - osteoblasts (bone forming) - osteoclasts (bone destroying) - osteogenic cells (stem cells) |
| What is the endosteum? | - delicate membrane on the internal surfaces of bone - covers the spongy bone - simple layer of osteogenic cells - which can differentiate into osteoblasts - also contains osteoblasts/clasts |
| Osteoid is secreted by ....... and it contains ........ and ............ | Osteoid is secreted by osteoclasts and it contains both ground substance (proteoglycans and glycoproteins) and collagen fibres |
| What are ostocytes? | - mature osteoblasts |
| 2/3 of total bone mass is made up of what? | - hydroxyapatites - primarily calcium phosphate crystals - they are responsible for the hardness and resistance to compression of bone |
| What are canaliculi? | - fine passageways that form a branching network for the exchange of materials between blood vessels and osteocytes |
| What cells are responsible for resorbing bone during bone remodelling? | Osteoclasts |
| What are some functions of skeletal muscle? | - produce skeletal movements e.g. pull tendons and move eyelids up (LPS) - maintain posture and body position - support soft tissue - to support the weight of visceral organs and shield internal tissues from injury - guard entrances and exits e.g. eyelids |
| Muscle is bundled into ...... and they are wrapped by their own layer of connective tissue called ........ | Muscle is bundled into fasicles and they are wrapped by their own layer of connective tissue called perimysium |
| The muscle fibres within each fasicle are separated by a layer of connective tissue called .... | endomysium |
| Whole muscles are covered by a dense layer of collagen fibres called .... | epimysium |
| Compare the position and number of nuclei in cells of skeletal muscle vs smooth muscle? | - skeletal muscle - there are many nuclei per cell - located outside the cell - smooth muscle - each cell has one nucleus - within cell |
| What is the smallest functional unit of a muscle fibre? | - a sarcomere - the region of myofibril between two successive Z discs - composed of thin (actin) and thick (myosin) myofilaments |
| Where is the H zone and what is it made of? | - it is the light area in the middle of A band - only myosin filaments |
| What is the Neuromuscular Junction (NMJ)? | - intercellular connection between motor neuron and skeletal muscle fibre - the muscle fibre only contracts under control from the NMJ - one NMJ per muscle fibre |
| What are the two functional divisions of the Peripheral Nervous System? | 1. Sensory (Afferent) division - somatic sensory fibres convey impulses from skin, cornea, conjunctiva etc. 2. Motor (efferent) division) - Autonomic and sensory divisions - transmits impulses from the CNS tot he effector organs i.e. muscles and glands |
| What are the two principle cell types in nervous tissue? | - neuroglia = small supporting cells that surround and wrap delicate neurons - neurons = excitable cells - transmit electrical signals |
| What is the function of astrocytes? | - support and brace neurons - can contact both capillaries and neurons - control chemical environment around neurons |
| What is the purpose of oligodendrocytes? | - Oligodendrocytes have processes that from myelin sheaths around CNS nerve fibres - myelin sheaths are important for increased propagation of action potentials |
| What is the function of satellite cells? | - similar to astrocytes of CNS but for PNS - surround the neuron cell bodies of the PNS |
| What is the function of Schwann cells? | - similar to oligodendrocytes of CNS but for PNS - surround all peripheral nerve fibres - form myelin sheaths around thicker nerve fibres - regenerate damaged peripheral nerve fibres |
| What are dendrites? | - short and tapering processes - diffusely branched - receptive (input) region of neuron - convey incoming messages to the cell body as graded potentials |
| Compare myelination in CNS and PNS? | - in the CNS one oligodendrocyte sneds out many processes and thus assists in myelination of several axons - in the PNS only one Schwann cell can myelinate one segment of one axon |
| What are anaxonic neurons? | - poorly understood function - dendrites and axons look alike - located in brain and special sense organs |
| What are bipolar neurons? | - found in the retina - two distinct processes 1. one with branching dendritic processes 2. one axon - short |
| What are unipolar neurons? | - dendrites and axons are continuous - cell body lies off to one side - most of the sensory neurons of the PNS - can be long |
| What are multipolar neurons? | - two or more dendrites - one axon - most common of CNS - can be long |
| What is epineurium? | - tough, fibrous sheath around a nerve, surrounds all fasicles |
| What is perineurium? | - coarse connective tissue that bundles fibres into fasicles |
| What is endoneurium? | - delicate connective tissue that encloses axons and their myelin sheaths |
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