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Topic 1 1.1.1 define: atom, molecule, organelle, cell, tissue, organ, organ system; give an example of each & localize each in the hierarchy of anatomical structure The Structural Organization of the Human Body Atoms: smallest particle of an element with all the properties of that element – what are the different parts of an atom??
- Protons: Positively charged located in the nucleus
- Neutrons: No charge (neutral) located in nucleus
- Electrons: Negatively charged, located in the nucleus Molecules: the smallest amount of a substance that can exist alone = a combination of atoms Organelles: molecules associate in specific ways to form organelles = basic components of living cells – 5 examples of organelles
- Nucleus
- Mitochondrion
- Nucleolus
- Ribosome
- Cytoplasm Cells: fundamental structural & functional unit of a living thing; cells vary widely in size & shape, reflecting unique functions in the body ➔ Smallest cell: Red Blood Cells ➔ Largest cell: Muscle Cells When cells become specialized, they lose the ability to reproduce due to all of the cells coming together Cells are very diverse and have many different functions and lifespans. Some are regenerative and can last forever (muscle cells) whereas others are not regenerative and if damaged cannot be repaired (neurons) *Cells are always communicating. Signals are always being sent to the cells because of the nucleus. Cells has 3 main parts:
- Plasma membrane- outer boundary of cell
- Cytoplasm – intracellular fluid packed with organelles.
- Nucleus – controls cellular activities
Cell diversity Cells that connect body parts. Form linings or transport gases
- Epithelial cells
- Fibroblasts
- Erythrocytes Cells that move organs and body parts
- Skeletal Muscle cells
- Smooth Muscle cells Cells that store nutrients
- Fat cells Cells that fight disease
- Macrophage Cell that gathers info and controls body functions
- Nerve cell Reproduces
- Sperm and ovum Organ systems: organs that work closely with one another to accomplish a common purpose; eg: Name some organs associated with each of these systems.
Peroxisomes (^) • Absorb nutrients that cell has acquired.
- Digest fatty acids
- Plays a part in the way organisms digest alcohol. Because of this you can assume that the liver has more peroxisomes Microtubules • Extend throughout cell providing it with proper shape and keeps organelles in place.
- Largest structures in cytoskeleton and are about 24nm thick.
- Facilitate cell movement, cell division, and transportation of materials within cells Microfilaments • Assist with cell movement and are made of actin.
- Actin works with myosin to produce muscle movements, cell division, and cytoplasmic streaming.
- Keep organelles in place within the cell Intermediate Filaments
- Not directly involved in cell movement. Instead, they appear to play basically a structural role by providing mechanical strength to cells and tissues Centriole • Paired barrel shaped organelles located in cytoplasm of animal cells near nuclear envelope.
- Play a role in organizing microtubules that serve as the cells skeletal systems.
- Help determine locations of nucleus and other organelles within a cell Cilia (^) • Move water relative to cell in a regular movement of the cilia.
- Either results in cell moving through water, or moving water and its content across surface of the cell
Flagella (^) • Microscopic hair-like structures involved in locomotion of cell.
- Flagellum means whip.
- The whip like shape helps propel cell through liquid.
- Helps bypass the bodies defense cells (white blood cells) Microvilli • Digestion and absorption of intestinal contents by enlarging the absorbing surface approximately 25 x.
- Secretes enzymes disaccharidase and peptidase that hydrolyze disaccharides and polypeptides to monosaccharides and dipeptide to amino acids respectively. Nucleus • Produces and assembles cells ribosomes.
- Where ribosomal RNA genes are transcribed Nuclear Membrane
- Separates the contents of nucleus from cytoplasm.
- Only permeable to small nonpolar molecules Depicted in the picture of the nucleus Nucleoli (^) • Transcribes and processes rRNA.
- Ribosome subunit assembly Depicted in the picture of the nucleus Chomatin (^) • Genetic material that packages DNA into a unit that can fit within tight space of a nucleus. 2 types
- Euchromatin: less condensed, gene-rich, more easily transcribed.
- Heterochromatin: highly condensed, gene-poor, transcriptionally silent
functions of various epithelia:
- protection (mechanical, chemical, infectious) – skin,
- absorption - GI tract,
- filtration - kidney,
- excretion - kidney,
- secretion - glands,
- sensory reception - taste buds, olfactory membranes...
- All epithelial tissues is supported by connective tissue Basement membrane: epithelial tissue makes basal lamina and connective tissue makes reticular lamina and they come together between the two and are called the basement membrane. Epithelium is innervated and Avascular. Innervated = supply nerves to A = not Vascular = blood vessels in it The epidermis doesn’t bleed because it is Avascular. It is when you hit the Dermis that you bleed because it is vascular. Components of Epithelial Tissue When there is stress and tension where cell is being pulled apart you will see desmosomes which are proteins *The main reason out bodies maintain homeostasis is to keep proteins functioning properly Desmosomes: Big plaques that help maintain structure of cell by maintaining direct cell to cell contacts and providing anchorage Hemidesmosomes: Anchors the basal plasma to the basal lamina. Found in Basal membrane. Tight junctions: impermeable junction that encircles the cell. Impedes the passage of molecules and ions between cells. They act as barriers. Apical: faces surface Basal: Bottom Basal Lamina: Non cellular. Connects epithelium to connective tissues and created a tight barrier between two. Microvilli: finger like extensions of the plasma membrane that increase epithelial tissues surface area. (Look like hairs) Cilia: tiny hair-like projections used to move a cell or move things past a cell Tumours: 2 types. In epithelial or connective Epithelial tissues divide at a rapid rate. If mutations occur cancer can begin. When the mutated cells begin to secrete enzymes that can break through the basement membrane it invades the underlying tissue and the cancer enters the blood stream, or lymphatic system and travels through and goes through extravasation which creates secondary tumours. Benign: Basement membrane has not been breached
Invasive: Basement membrane has been breached 1.3.4 list and demonstrate your understanding of 7 special structural characteristics of epithelial tissue.
- cellularity: composed almost entirely of cells bound closely together by specialized junctions. As a result, epithelial tissue has little or no intercellular space.
- specialized contacts: tight junctions & desmosomes – Tight junctions to prevent material from passing between cells and Desmosomes to form links between cells and provide connection between intermediate filaments of cells cytoskeletons of adjacent cells. This gives strength to tissue.
- polarity: apical and basal polarity which results from different distribution of phospholipids, protein complexes and cytoskeletal components between various plasma membrane domains. This allows epithelial cells to transport molecules across the surface in a directional manner. Lost polarity is associated with the ability to differentiate into another cell type.
- basal lamina: noncellular, underlying supportive sheet of primarily glycoproteins - What are two functions of a basal lamina?? – provides support to epithelium and limits contact between epithelial cells and other cell types within tissue. Acts as a filter allowing only water and small molecules to pass through.
- supported by connective tissue: basement membrane = basal lamina + underlying reticular CT (what is reticular CT??) – provides support and connection an important feature of cancerous epithelial cells is failure to respect the boundary imposed by the basement membrane.
- innervated but avascular: how nourished? – All cellular nutrients are delivered and al wastes must be removed by diffusion
- regeneration: high regenerative capacity - Why?? – because it is constantly damages, lost or shed at exposed internal and external surfaces of the body. This means that they are constantly replaced through mitosis of stem cells found inside epithelium Classification of Epithelial Tissue Cell Shape Layers
- Squamous Simple epithelia
- Cuboidal Stratified epithelia
- Columnar 1.3.6 list the 4 types of simple epithelia; indicate primary functions associated with each & sample body locations Examples of Simple Epithelia: (absorption, secretion, filtration)
- simple squamous epithelium : thin & permeable - filtration, diffusion - eg: endothelium & in kidney, lungs
Exocrine Glands:
- mucous, sweat, oil/salivary glands, liver, pancreas, etc. a) Unicellular exocrine glands :
- no ducts because only one cell!
- really just the goblet cells (digestive & respiratory tracts) b) Multicellular exocrine glands :
- epithelium-derived duct & secretory cells; surrounded by supportive CT which brings blood vessels & nerves Membranes:
- Cutaneous membrane (skin) covers the body surface
- Mucous membrane (mucosae) mucous membranes line body cavities that are open to exterior
- Serous membranes line body cavities that are closed to exterior. Keeps organs moving freely making sure they don’t stick together (iii) Secretory method:
- merocrine/ eccrine : exocytosis most common type. pancreas, salivary glands, most sweat glands
- holocrine: cell rupture; only sebaceous glands
- apocrine: cell apex pinches off with secretory product Is mammary gland apocrine or merocrine? **Match the epithelial type with correct location
- Simple columnar** lines stomach, most of intestines 2. Simple squamous lines inside of the mouth 3. Pseudostratified ciliated columnar lines much of the respiratory tract 4. Simple squamous composes the endothelium. 5. Simple squamous composes the lung alveoli
What gland type secretes continuously by exocytosis?
- Merocrine glands secrete their products through exocytosis 1.3.9 list the 5 types of CT; list the 4 main functions associated with CTs
- 5 major types: mesenchyme , CT proper, cartilage, bone & blood
- main functions: (1) binding or support - eg: osseous (2) protection - eg: blood (3) insulation - eg: adipose (4) transportation - eg: areolar 1.3.10 describe the structural organization of CT in general; distinguish between collagen, elastic & reticular fibers; distinguish between “blast” and “cyte” types of CT cells Structural Elements of CT: a) Ground substance: interstitial fluid + cell adhesion proteins & proteoglycans : molecular sieve
- fibronectin, laminin - help cells attach to CT elements
- proteoglycans - What are these? What do they do? Interstitial fluid: has nutrients for cell. Contains proteins and other stuff Proteoglycans: Absorb water when injury occurs *IF SOMETHING ENDS WITH ‘IN’ ITS PROBABLY A PROTEIN b) Fibers: Collagen fibers : high tensile strength – prevent stomach from busrting apart when it gets stretched Elastic fibers : elastin has coiled structure to allow stretch + recoil. Stretchy and soft Reticular fibers : thin collagen protein; fine network to support blood vessels, soft tissues Reticular = 3 D web netlike strucutres
(ii) ADIPOSE TISSUE: areolar CT modified to store nutrients; adipocytes Adipocytes: cell specialized for storage of fat, found in connective tissue Description: fat-filled adipocytes with displaced nuclei; do not reproduce; scanty matrix Location: under skin, around kidneys & eyeballs, in bones & within abdomen, in breasts; 18% of average wt (15% ♂ & 22% ♀) Function: fuel reservoir, insulation, supports & protects organs (iii) RETICULAR CT: like areolar CT, but only reticular fibers Loc: • lymphoid organs (lymph nodes, bone marrow, spleen) Fcn: • fibers form soft internal skeleton that supports free blood cells 1.3.12 list and briefly describe the 3 types of dense CT DENSE CT (fibers are the predominant element!!) (i) DENSE REGULAR CT: bundles of collagen fibers running parallel to direction of pull → white, flexible tissue with great resistance to tension Location: tendons (muscle to bone), ligaments (bone to bone at joints), also aponeuroses Aponeuroses: sheet of pearly white fibrous tissue that replaces a tendon in flat muscles having a wide area of attachment Function: attachment with strength (ii) DENSE IRREGULAR CT: same as regular, but collagen bundles thicker & arranged irregularly Location: Found in organs where there are a lot of stress in different directions like uterus, stomach, digestive tract. Dermis, submucosa of digestive tract, fibrous capsules of organs & joints Function: withstand tension exerted in many directions; strength (iii) ELASTIC CT: like dense regular CT, but a very high content of elastic fibers; found in some very elastic ligaments (ie. connecting vertebrae)
1.3.13 List the other remaining types of connective tissue
3. CARTILAGE features between dense CT & bone → tough, but flexible (i) avascular, devoid of nerve fibers (ii) ground substance contains lots of the GAGs chondroitin sulfate & hyaluronic acid - also chondronectin, (adhesive protein) (iii) collagen fibers (can have some elastic fibers) (iv) up to 80% H 2 O Hyaline Cartilage: glassy, in the costal cartilage of the ribs. Has a lot of strength and very good for supporting. Has more flexibility than bone Fibro Cartilage: Collagen fibers are arranged in a different way. Pubic symphysis and intervertebral discs. Allows for more flexibility and movement. Elastic Cartilage: epiglottis, ear, bendy and bounces back. 4. BONE: calcium salts give hardness & strength for support/protection of softer tissues; cavities for fat storage & synthesis of blood cells 2 types of bone Spongey: found inside the bone, Compact: outside of the bone. osteoblasts: found in membrane outside of bone and inside bone. Periosteum and Endosteum cells that form bone tissue secrete bone matrix and participate in mineralization of bone to regulate d balance of calcium and phosphate ions. osteocytes: cell that lies within substance of fully formed bone. Derived from osteoblasts. Osteoclasts: Found in Periosteum and Endosteum. Constant remodelers of bone. Secrete enzymes and acids to break down minerals. Cells that degrade bone to initiate normal bone remodeling and mediate bone loss by increasing resorptive activity. 5. BLOOD : classified as a CT because it consists of cells (RBCs, WBCs) surrounded by a nonliving fluid matrix, blood plasma “fiber” components are soluble protein molecules - only visible during clotting.
