Module 1 (cells and tissues) Flashcards
6 levels of structural organisation in the human body
Chemical, cellular, tissue, organ, system, organismal
Chemical level
Atoms and molecules
Cellular level with example
A combination of chemicals, acquire specific functions - smooth muscle cells
Tissue level with example
Cells combined together performing a specific function - muscle tissue
Organ level with example
2 or more different tissues joined to provide a function - stomach
System level with example
Many organs together - digestive system
Organismal level
All systems joined together
Four main types of tissues
Epithelial, connective, muscle and nervous
Eleven body systems
Integumentary, endocrine, digestive, nervous, respiratory, urinary, cardiovascular, reproductive, skeletal, muscular, immune
Integumentary system components (5)
Skin (epidermis, dermis and hypodermis), hair follicles, nails, oil glands and sensory
Integumentary system function (7)
Protection (surface and deeper tissues), temperature regulation, waste elimination, production of vitamin D, fat storage, detects sensations and insulation
Skin’s 4 parts and functions in integumentary system
Cutaneous membrane: protection
Epidermis: vitamin D production
Dermis: feeds epidermis, strength, contains glands
Hypodermis: stores fat and attaches skin to deeper layers
Hair’s 3 parts and functions in integumentary system
Hair follicles: produce hair, connects to nerves so provides sensation
Hair: protection
Sebaceous glands: lubricates hair shaft and epidermis, removes waste
Sweat glands’ function in integumentary system
Thermoregulation (evaporation through sweat)
Which systems does breast tissue belong to?
Reproductive system for nutrition for new-born and integumentary system due to being a modified sweat gland
Nails function in integumentary system
Stiffen and protect digits
Sensory receptors’ function in integumentary system
Detects sensations (touch, pressure, temperature, pain)
Muscular system components (3)
Skeletal muscles (axial and appendicular), tendons and aponeuroses
Skeletal muscles function in muscular system
Provide skeletal movement, control entrances and exits to digestive, respiratory and urinary systems, produce heat, support skeleton and protect soft tissues
Axial muscles function in muscular system
Provide support and positioning of the axial skeleton
Appendicular muscles function in muscular system
Support and move brace limbs
Tendon function in muscular system
Wire muscles to bones with fibrous connection, convert contractile forces of muscles to movement
Aponeuroses function in muscular system
Form fibrous connections between muscles, convert contractile forces of the muscles to movement
Skeletal system components
Bones, cartilage and joints, axial skeleton, appendicular skeleton, red and yellow bone marrow
Skeletal system function
Supports and protects body, provides surface area for muscle attachments, aids body movements, produces blood cells, stores minerals and fats
Axial skeleton function in skeletal system
Protects brain, spinal cord, sense organs and soft tissues of thorax; supports weight over lower limbs and provides structure for muscles.
Appendicular skeleton function in skeletal system
Provides internal support and positioning of external limbs, supports and enables muscles to move axial skeleton
Yellow and red bone marrow functions and relationship
Red produces red blood cells (found in flat bones). Yellow stores fat cells and minerals (found in medullary cavity of long bones). As we age, we lose red and gain yellow bone marrow. Yellow to red after major bleeding.
Nervous system components
CNS (brain, spinal cord, special sense organs) and PNS (all nervous tissues outside CNS)
Nervous system function
Produce nerve impulses (action potentials) to regulate body activities, detects and interprets changes in internal and external environments and responds by causing muscular contractions or glandular excretions
Brain function in nervous system
Complex integrative activities, controls voluntary vs involuntary
Spinal cord function in nervous system
Relays information to/from brain. Less complex integrative activities.
Sensory organs function in nervous system
Sensory input to brain (sight, smell, hearing, taste and equilibrium)
CNS and PNS function in nervous system
CNS is the control centre and can have short term control over other systems.
PNS: links CNS to all other organs of body
Maintain homeostasis, initiate voluntary movements and responsible for perception, behaviour and memory
Cartilage function
Sit at interface between bones as a buffer so bone doesn’t rub on bone
Megakaryocytic cells
Make platelets for clotting
Reflex arc
Touch something hot, pull arm away without thinking about it. Reflex is mediated in spinal cord and pain receptor (the motor nerve) is put into action and so the limb moves.
Cardiovascular system components
Heart, blood, blood vessels
Cardiovascular system function
Pump blood throughout body, remove cell waste, regulate pH, temperature and H2O concentration, provide defence and repair damaged blood vessels
Heart function in cardiovascular system
Propels blood through vessels and maintains blood pressure
Blood function in cardiovascular system
Transports O2, CO2, minerals and hormones; removes waste, regulates temperature, provides defence and balances pH
Blood vessels functions in cardiovascular system
Arteries carry oxygenated blood from the heart; veins carry deoxygenated blood to heart; capillaries are a site of diffusion between blood and interstitial fluids
Lymphatic and immune system components
Lymphatic fluid and vessels, B and T cells, lymph nodes, spleen, thymus and tonsils
Lymphatic and immune system function
Returns proteins and fluid leftover from capillary diffusion to blood; carries lipids form gastrointestinal tract to blood; contains sites of maturation of B and T cells to protect against pathogens
Lymphatic fluid and vessels function in lymphatic and immune system
Carry lymph fluid (water and protein) and lymphocytes from outer tissues to CV system. Carry lipids from gut to CV system
Lymph nodes/tonsils function in lymphatic and immune system
Monitor composition of lymph. Engulf pathogens for defence and stimulate immune response.
Spleen function in lymphatic and immune system
Monitors blood cell circulation, engulfs pathogens, recycles red blood cells and stimulates immune response
B and T cells function in lymphatic and immune system
Carry out immune responses
Which systems does the thymus belong to?
In lymphatic and endocrine systems, controls the development/maintenance of T cell lymphocytes. Inconspicuous in adults
Reproductive system components
Males: testes, epididymus, ductus/vas deferens, seminal glands, prostrate gland, urethra, penis and scrotum
Females: ovaries, uterine tubes, uterus, vagina and mammary glands
Reproductive system function
Production of gametes and hormones, transport and storage of gametes and milk production
External genitalia function in reproductive system
Reproduction (and thermoregulation of testes in males)
Fallopian tubes function in reproductive system
Location of fertilisation; delivery of oocyte
Uterus function in reproductive system
Site of embryonic development
Vagina function in reproductive system
Lubrication, sperm reception and birth canal
Which systems do the gonads belong to?
Endocrine system for secreting hormones and reproductive system for producing sex cells.
Urinary system components
Kidneys, bladder, ureters and urethra
Urinary system function
Produces, stores and eliminates urine, eliminates waste and regulates volume and chemical composition of blood; helps maintain the acid-base balance of body fluids; maintains the body’s mineral balance and helps regulate production of red blood cells.
Which systems do the kidneys belong to?
Urinary system to form and concentrate urine, regulate pH and ions, blood volume and blood pressure.
Endocrine system to produce hormones for calcium levels, increasing of blood pressure and the hormone EPO which stimulates an increased production of RBCs.
Ureters function in urinary system
Conduct urine to bladder
Urinary bladder function in urinary system
Stores urine before elimination
Urethra function in urinary system
Conducts urine to exterior
Respiratory system components
Nasal cavity and paranasal sinuses, pharynx, larynx, trachea, bronchi and lungs.
Respiratory system function
Gas exchange, pH balance and production of sounds
Nasal cavity function in respiratory system
Filter, warm and humidify air; detect smell
Which systems does the pharynx belong to?
Respiratory system (conducts air to larynx) and digestive system (brings solid food and liquids to oesophagus)
Larynx function in respiratory system
Protects opening to trachea and contains vocal cords for vocalisation
Trachea function in respiratory system
Filters air; kept open by cartilage
Bronchial tubes function in respiratory system
Conducts air between trachea and lungs (takes air to alveoli)
Lungs function in respiratory system
Air movement, gas exchange of oxygen and carbon dioxide in alveoli; acid-base control
Endocrine system components
Pineal gland, hypothalamus, pituitary gland, thymus, thyroid gland, parathyroid glands, adrenal glands, pancreas, ovaries and testes.
Endocrine system function
Regulate body activities by releasing hormones
Pineal gland function in endocrine system
Reproduction timing, day/night rhythms
Pituitary gland function in endocrine system
Controls other endocrine glands; controls growth and keeps fluid balance
Thyroid gland function in endocrine system
Found in throat; releases hormones to control metabolic rate and calcium level
Parathyroid gland function in endocrine system
Controls calcium levels
Adrenal gland function in endocrine system
Found on top of kidneys; water and mineral balance, tissue metabolism, cardiovascular and respiratory function (adrenaline - fight/flight)
Digestive system components
Oral cavity, salivary glands, pharynx, oesophagus, stomach, small intestine, liver, gallbladder, pancreas, large intestine and anus.
Digestive system function
Achieves physical and chemical breakdown of food, absorbs nutrients and eliminates solid wastes.
Oral cavity function in digestive system
Mechanical digestion - teeth and tongue
Salivary glands function in digestive system
Buffers and lubricant, production of enzymes (chemical breakdown)
Oesophagus function in digestive system
Deliver food to stomach
Stomach function in digestive system
Enzyme and acid production for chemical breakdown; muscular contractions for mechanical breakdown; hormone production
Small intestine function in digestive system
Produces digestive enzymes, buffers and hormones and absorbs nutrients
Large intestine and anus function in digestive system
Water removal and absorption, waste storage and removal.
Which systems does the pancreas belong to?
Endocrine system for glucose control.
Digestive system for producing and secreting enzymes which help break down food in the lumen; produce buffers and endocrine cells.
Liver function in the digestive system
Produces and secretes bile to regulate nutrients in the blood stream
Gallbladder function in the digestive system
Stores, concentrates and secretes bile
EPO
Erythropoietin is a glycoprotein hormone produced by the kidneys, signalling for erythropoiesis in the bone marrow which stimulates red blood stem cells and more RBCs are produced. Allows for a greater O2 carrying ability in the blood
Four types of tissues and basic function
Epithelial, muscle, nervous and connective. Contribute to homeostasis by providing support, communication among cells and resistance to disease
Epithelial tissue description
Covers body surfaces, lines hollow organs, tubes, cavities and ducts; forms glands
Epithelial tissue function
Protection, filtration, secretion, absorption, excretion; allows body to interact with internal and external environments
Connective tissue description
Cells in a matrix of fibres and ground substance
Connective tissue function
Protects and supports, binds organs together, stores energy and helps provide body with immunity to disease-causing organisms
Muscular tissue description
Composed of cells specialised for contraction and generation of force.
Muscular tissue function
Generates heat that warms the body while providing movement
Nervous tissue description
Conducting nerve cells and supporting neuroglia
Nervous tissue function
Detects changes in a variety of conditions inside and outside the body, responds by generating nerve impulses which activate muscular contractions and glandular secretions.
Different surfaces of epithelial cells
Apical, lateral and basal
Apical surface and what can be found on it
Also called the free surface, the top of the cell and open to the outside world, not touvhing other cells
Cilia or microvilli
Basal surface and basal junction name
Also called the attached surface, the bottom of the cell and attaches to the basement membrane
Hemidesmosome
Lateral surface and types of lateral junctions (4)
The sidewalls of the cells, where 2 cells are adjacent to each other
Tight, adherens, gap and desmosome
Cytoskeleton description and components
Protein skeleton for cells; microfilaments and intermediate filaments
Microfilaments example and function in cytoskeleton
E.g. Actin; bundles beneath and links cell membrane and cytoplasm, provide strength, later cell shape, ties cells together and initiate movements for muscle contraction
Intermediate filaments example and function in cytoskeleton
E.g. Keratin; provides strength, moves and trafficks materials through cytoplasm; larger than microfilaments
Tight junctions description and function; proteins involved
Knitted-type appearance; removes the gap between 2 adjacent cells with individual sealing-strands to keep cells “electrically tight”/maintain polarity so ions and proteins cannot pass down easily
Claudins and occludins proteins bind to membrane
Adherens junction description and function; proteins involved
Adhesion belt encompasses the cell (smaller/less continuous ‘belts called ‘plaques’), cadherin protein spans gap between cells, goes through membrane and interacts with catenin protein; catenin links cadherin to actin in microfilaments of one cell’s cytoskeleton to another; more basal located than tight junctions
Links cytoskeletons together to prevent unwanted individual movement of cells (from contractions)
Desmosome junction description and function; proteins involved
Adhesive plaques similar to adherens junction; gap between membranes of adjacent cells, spanned by cadherin protein which links intermediate filaments keratin between each cell together
cadherin protein spans gap between cells and links the intermediate filaments between different cells (keratin in each membrane)
Add connections between cells to add additional stability to epithelium to resist shearing forces and prevent pulling apart
Gap junction description and function; proteins involved
Formed by a combination of 6 connexIN proteins from each cell (called a connexON/hemichannel); connexON is closed when first made, but once it finds a connexOn from an adjacent cell, a channel between them opens; gap junctions can aggregate together to form communication plaques
Direct connection between cells allow small molecules to traverse back and forth, allows for coordinating function in a set of cells.
Linking proteins in lateral junction
Cadherin, connexIN, claudin and occludin
Anchoring proteins in lateral junction
Actin and keratin filaments
Hemidesmosome junction description and function; proteins involved
On the basal surface; links cellular basal intermediate filament (keratin) to basement membrane; integrin protein used as a linker protein which binds to laminin protein in the basement membrane and to keratin in the cytoplasm
Prevents unwanted individual cell movement across the basement membrane
Basement membrane function and components
Supports overlying epithelium, provides a surface where epithelial cells migrate during growth and wound healing, acts as a physical barrier and participates in the filtration of substances in the kidney. Made up of the basal and reticular laminas.
Basal lamina description and function
Basement membrane layer closer to and secreted by epithelial cells. Contains collagen and laminin proteins and attaches the epithelial cells to the basement membrane
Reticular lamina description and function
Basement membrane layer closer to the connective tissue cells. Produced by the fibroblasts in the connective tissue and contains fibrous proteins such as fibronectin and collagen
Nutrient and waste exchange in epithelia
Epithelia contain nerves but no blood vessels (avascular) and so exchange of wastes and nutrients occurs through diffusion from vessels in the connective tissue across the basement membrane
Types of epithelial tissue
- Covering and lining epithelia
Covering epithelia: form the outer covering of the skin and some internal organs; lining epithelia: form the inner lining of blood vessels, ducts and body cavities, and the interior of the respiratory, digestive, urinary and reproductive systems - Glandular epithelia constitute the secretory portion of glands
Arrangements of cells in layers (covering and lining epithelia)
Simple: single layer (secretion; absorption; filtration)
Stratified: two or more layers (protective)
Pseudostratified: appears to have multiple layers, single layer; only some cells have apical surfaces but all reach BM; has goblet cells
Shapes of cells (covering and lining epithelia)
Squamous: flat and thin (help allow passage by diffusion)
Cuboidal: about as tall as they are wide with round-looking nucleus in the middle (secretion; absorption)
Columnar: more tall that wide with elongated nuclei (secretion; absorption)
Transitional: a stratified epithelium in which the cells can change shape from cuboidal to flat to accomodate stretch (e.g bladder)
Simple squamous cells
A single layer of cells with centralised nuclei; most delicate epithelium.
Where are simple squamous cells found?
Mesothelium: when SSE cells are lining inside of abdominal organs, forming a layer in the serous membranes (pericardial, pleural, peritoneal cavities)
Endothelium: when SSE cells are lining inside of vessels (heart and blood and lymphatic vessels)
Simple squamous cells function
Filtration (kidney), diffusion (lung) and secretion where a slippery surface is needed (outer layer of serous membranes); not for protection due to thinness
Simple cuboidal cells
A single layer of cube shaped cells with centralised nuclei
Where are simple cuboidal cells found?
Anterior surface of lens, pancreatic and kidney ducts, secretory portion of glands (thymus, thyroid), pigmented epithelium at posterior of retina, ovary surface
Simple cuboidal cells function
Secretion and absorption
Non-ciliated simple columnar cells
Single layer column-shaped cells with nuclei near base. Can have microvilli (non-motile cytoplasmic projections; increase SA:V ratio and rate of absorption); have goblet cells which secrete mucous material at apical surface
Where are non-ciliated simple columnar cells found?
Line gut mucosa from stomach to anus, ducts of many glands, gall bladder
Non-ciliated simple columnar cells function
Goblet cells secrete mucous for lubrication which helps prevent damage to the delicate tracts they line; microvilli absorb
Ciliated simple columnar cells
Single layer column-shaped cells with nuclei near base. Have cilia which move and goblet cells.
Where are ciliated simple columnar cells found?
Bronchioles (move material that has come into lungs up through bronchi and towards trachea), uterine fallopian tubes (sweep egg along), sinuses, central canal of spinal cord and ventricles of brain
Ciliated simple columnar cells function
Synchronised movement of cilia assists movement of mucous and foreign objects or oocytes for expulsion or transport; better for secretion than cuboidal as they are larger and have more room for organelles
Stratified squamous cells and specialised subtypes
Multiple layers of cells; flatter outer layers and cuboidal inner layers. Outer layers hardened and tough due to dehydration (further from blood supply). As cells migrate up epithelium they die and leave keratin at surface
Keratinised: (apical cells) hard and tough to protect against dehydration
Non-keratinised: soft due to external moistening
Where are stratified squamous cells found?
Keratinised: skin
Non-keratinised: lines wet surfaces; mouth, tongue, oesophagus, anus and vagina
Stratified squamous cells function
Protect against abrasion, dehydration, the entry of microbes. Where mechanical or chemical stresses are severe, can afford to lose some layers without compromising barrier function.
Pseudostratified columnar cells and specialised subtypes
Single layer of rectangular cells with nuclei at varying heights. All reach the BM but not all have an apical surface; appears to have several layers
Ciliated: cilia on some cells; secrete mucous form goblet cells
Non-ciliated: no cilia and no goblet cells
Where are pseudostratified columnar cells found?
Ciliated: most of upper airways; lines respiratory tract
Non-ciliated: large ducts of glands, epididymus, part of male urethra
Pseudostratified columnar cells function
Ciliated: Secrete and move mucous
Non-ciliated: absorption and protection
Stratified cuboidal cells
Many layers of cube-shaped cells
Where are stratified cuboidal cells found?
Ducts of adult sweat glands, oesophageal glands, male urethra
Stratified cuboidal cells function
Protection, some secretion and absorption
Stratified columnar cells
Many layers of rectangular-shaped cells; rare
Where are stratified columnar cells found?
Part of urethra, some large gland ducts (oesophageal), anal mucosal membrane and part of conjunctiva of eye
Stratified columnar cells function
Protection and secretion
Endocrine glands
Glands that secrete directly into blood usually via transversing interstitial fluid; don’t go into a duct
Exocrine glands
Produce and secrete fluid which goes into ducts that empty onto the surface of a covering or lining epithelium; from there either absorbed or transferred elsewhere
Single cell gland
Unicellular gland found in exocrine glandular epithelia; example: goblet cell - apical cytoplasm filled with large secretory vesicles
Different duct structures
Simple: single duct that does not divide on its way to gland cells
Compound/complex/branched: duct divides one or more times on its way to the gland cells
Different secretory area structures
Tubular: glandular cells form tube-shapes, can be coiled or branched in simple ducts
Alveolar/acinar: glandular cells form sac-like pockets, can be branched in simple ducts
Tubuloalveolar: secretory cells form both tubes and sacs
Where are simple tubular glands found?
Intestinal glands
Where are simple coiled tubular glands found?
Merocrine sweat glands
Where are simple branched tubular glands found?
Gastric glands and mucous glands of oesophagus, tongue and duodenum
Where are simple alveolar glands found?
A stage in the embryonic development of simple branched glands
Where are simple branched alveolar glands found?
Sebaceous (oil) glands
Where are compound tubular glands found?
Mucous glands (in mouth), bulbo-urethral glands (in male reproductive system) and seminiferous tubules of testes
Where are compound alveolar glands found?
Mammary glands
Where are compound tubuloalveolar glands found?
Salivary glands, glands of respiratory passages and pancreas
Connective tissue formula
CT = ECM (extracellular matrix) + cells
Connective tissue features
Not found on body surfaces (found where bones, cartilage and blood is located); can be highly vascular (except for cartilage - avascular, and tendons - very little blood supply); supplied by nerves (except for cartilage)
Extracellular matrix
ECM = Ground substance + fibres
Material located between connective tissue cells. Protein fibres are secreted by the connective tissue cells; structure of ECM largely dictates the connective tissue qualities
Connective tissue cell types
Fibroblasts, macrophages, plasma cells, mast cells, adipocytes, leukocytes
-blast vs -cyte
Blast is immature; retain the capacity for cell divison and secrete the ECM; differentiate into mature cyte cells once the ECM is produced and have reduced capacities for cell division and ECM formation; mostly involved in monitoring and maintaining ECM
Fibroblasts
Large, flat cells widely distributed in CT (migratory; able to move so they can reconstitute the BM) which secrete fibres and ground substance (ECM components)
Macrophages
Develop from monocytes - type of WBC; have an irregular shape with branching projections; engulf bacteria and cellular debris by phagocytosis.
Fixed: stay in a certain tissue
Wandering: move throughout tissue and gather at sites of infection
Plasma cells
Small cells that develop from WBC called B lymphocyte; secrete antibodies (proteins) which attack/neutralise foreign substances; reside in gastrointestinal and respiratory tracts, salivary glands, lymph nodes, spleen and red bone marrow
Mast cells
Produce histamine which dilates small blood vessels in response to inflammation; bind to, ingest and kill bacteria; found alongside blood vessels supplying CT
Adipocytes
Fat/adipose cells which store fats; found deep under skin and around organs
Leukocytes and subspecies
WBCs which migrate from blood to CT and instigate immune responses; not usually found in CT
Eosinophils move to sites of parasitic infection/allergic responses
neutrophils move to sites of infection and destroy microbes by phagocytosis
Ground substance description and function
Material between cells and fibres; supports and binds cells, stores water and provides a medium for substance exchange between blood and cells; may be fluid, semifluid, gelatinous or calcified
Ground substance components
Water, adhesion proteins and polysaccharide chains (GAGS) - which can be sulphated or non-sulphated
Sulphated GAGS and where they are found
Chondroitin sulphate: cartilage, bone, skin and blood vessels
Dermatan sulphate: skin, tendons, blood vessels and heart valves
Keratan sulphate: bone, cartilage and cornea
All bind to proteins to form proteoglycans
Non-sulphated GAG and function
Hyaluronic acid - viscous slippery substance which binds cells together, lubricates joints and helps maintain eyeball shape. Does not bind directly to protein backbone but is joined to various proteoglycans. Broken up by hyaluronidase (produced by WBCs, sperm and bacteria) - which causes GS to become more liquid so cells can move easily in GS
GAGs important functions
Trap water and make GS more jelly-like; provide support and adhesion for cells
Main adhesion protein in CT
Fibronectin - binds to both collagen fibres and GS, links them together; attaches cells to GS
Non-sulphated GAG and function
Hyaluronic acid - viscous slippery substance which binds cells together, lubricates joints and helps maintain eyeball shape. Does not bind directly to protein backbone but is joined to various proteoglycans. Broken up by hyaluronidase (produced by WBCs, sperm and bacteria) - which causes GS to become more liquid so cells can move easily in GS
GAGs important functions
Trap water and make GS more jelly-like; provide support and adhesion for cells
Main adhesion protein in CT
Fibronectin - binds to both collagen fibres and GS, links them together; attaches cells to GS
Abnormal Periorbital ECM and thyroid diseases (Exopthalmos) with ECM
Autoimmune action of fibroblasts in ECM of eye where more ECM is laid down behind eyes and eyeballs are pushed forward; thyroid diseases such as goitre (swollen thyroid gland) due to autoimmune over-activation of the thyroid
Deposition of GAGs and influx of water increase orbital contents
Different types of CT fibres in the ECM and basic function
Collagen, reticular and elastic; strengthen and support CT
Collagen fibre
Strong but flexible to resist pulling forces, often occur in parallel bundles to increase tensile strength to tissue
Where are collagen fibres found?
Bone, cartilage, tendons and ligaments
Where are elastin fibres found?
Skin, blood vessels walls, heart valves and lung tissue
Where are reticular fibres found?
Stroma (supporting framework) of soft organs (spleen and lymph nodes), form part of BM
Elastin fibre
Smaller than collagen, branch and join to form a fibrous network within CT; made of elastin (protein) and fibrillin (glycoprotein) - adds strength and stability; strong and stretchy, able to return to original shape (elasticity)
Where are elastin fibres found?
Skin, blood vessels walls and lung tissue
Marfan syndrome
Mutation in gene coding for fibrillin; growth factor cannot bind properly to fibrillin to keep it inactive, so growth is increased
Large individuals with chest deformity and may have weakened heart valves and arterial walls
Embryonic CT types
Mesenchyme (embryonic) and mucous connective tissue
Mesenchyme embryonic CT
Irregularly shaped mesenchymal cells in semifluid GS containing delicate reticular fibres; found under skin and along developing bones of embryo, some in adult CT along blood vessels
Mucous embryonic CT
Widely scattered fibroblasts embedded in viscous, jellylike GS containing fine collage fibres; found in umbilical cord of foetus
Embryonic CT function
Mesenchyme: forms almost all other types of CT
Mucous: support
Mature CT types
Loose CT, dense CT, cartilage, bone tissue and liquid CT
Loose CT types
Areolar, adipose and reticular; arranged loosely between cells
Areolar loose CT
Widely distributed, like a ‘packing material’; consists of randomly arranged fibres (collagen, elastic and reticular) and all connective cells embedded in semifluid GS
Where is areolar loose CT found?
Found around almost every structure
Areolar loose CT function
Strength, elasticity and support
Adipose loose CT
Made from fibroblasts specialised for storing fats, have a centralised triglyceride droplet;
White adipose tissue - less vessels
Brown adipose tissue - more vascular
As more fat cells develop, more blood vessels appear
Where is adipose loose CT found?
With areolar CT (including fibroblasts); buttocks, flanks, abdomen, the orbit of eye
Adipose loose CT function
Reduces heat loss through skin, fat storage (energy reserves and insulation), supports and protects organs
Reticular loose CT
Interlacing network of reticular fibres and cells
Where is reticular loose CT found?
Stroma of liver, spleen, lymph nodes; red bone marrow, reticular lamina of BM, around blood vessels and muscles
Reticular loose CT function
Forms stroma of organs, binds smooth muscle tissue cells, filters and removes worn-out blood cells in spleen and microbes in lymph nodes
Dense CT and types
More densely packed due to fewer cells with more fibres; regular, irregular and elastic
Dense regular CT
Forms shiny white ECM; mainly collagen fibres regularly arranged in bundles with fibroblasts in between; slow healing due to non-living collagen
Where is dense regular CT found?
Tendons, ligaments and aponeuroses
Dense regular CT function
Provide strong attachment between various structures; withstands pulling along long axis of fibres
Dense irregular CT
Made up of collagen fibres - usually irregularly arranged with a few fibroblasts
Where is dense irregular CT found?
In sheets, such as fasciae (tissue beneath skin and around muscles and other organs), deep region of dermis, heart pericardium, bone periosteum, joint and membrane capsules and heart valves
Dense irregular CT function
Provides tensile (pulling) strength in many directions
Dense elastic CT
Contains mostly elastic fibres with fibroblasts between them; unstained tissue is yellowish
Where is dense elastic CT found?
Lung tissue, artery walls, bronchial tubes, trachea, vocal cords, suspensory ligaments of penis and some ligaments between vertebrae
Dense elastic CT function
Allows stretching and recoil of various organs (elasticity)
Cartilage CT
Dense network of collagen and elastic fibres embedded in chondroitin sulphate; has few cells and lots of ECM; strong and resilient with no nerves or blood vessels in ECM due to secretion of substance which prevents blood vessel growth - avascular and heals slowly. Mature chondrocyte cells occur singly or in groups called lacunae in ECM. Dense CT (perichondrium) surrounds most of cartilage, source of new cells
Cartilage CT function
Resists tension, compression and shear; support and embryonic growth
Cartilage CT types
Hyaline, elastic and fibrous
Hyaline cartilage CT
Gel as GS, fine collagen fibres; chondrocytes found in lacunae surrounded by perichondrium
Where is hyaline cartilage CT found?
Most abundant; ends of long bonds, anterior ends of ribs, parts of larynx, trachea, bronchi, bronchial tubes, embryonic and foetal skeleton
Hyaline cartilage CT function
Provides smooth surface for joint movement, flexibility and support. Can be fractured, as it is weak
Elastic cartilage CT
Chondrocytes in threadlike network of elastic fibres within ECM; perichondrium present
Where is fibrocartilage CT found?
Pubic symphysis, intervertebral discs, menisci of knee, portions of tendons
Fibrocartilage CT function
Support and joining structures together; strength and rigidity make it strongest cartilage
Where is elastic cartilage CT found?
Lid on top of larynx (epiglottis), external ear and auditory tubes
Elastic cartilage function
Provides strength and elasticity; maintains shape of certain structures
Growth types of cartilage CT
Interstitial and appositional (exogenous)
Compact bone components
Made up of osteons:
Lamellae: concentric rings (ECM) comprised of mineral salts (CaP and CaOH; for hardness) and collagen fibres (tensile strength)
Lacunae: small spaces between lamellae which contain mature bone cells (osteocytes)
Canaliculi: minute canals (containing EC fluid and minute osteocytic processes) that radiate from lacunae and provide routes for oxygen, nutrients and waste
Central canal: contains blood vessels, lymph and nerves.
Appositional (exogenous) growth of cartilage CT
Growth at outer surface of tissue; inner perichondrium cells become chondroblasts which surround themselves with ECM and become chondrocytes; ECM accumulates beneath perichondrium on outer surface of tissue and it widens; continues throughout adolescence
Compact bone components
Made up of osteons:
Lamellae: rings of ECM comprised of mineral salts (Ca, P) and collagen fibres which make bone strong and hard
Lacunae: small spaces between lamellae which contain mature bone cells (osteocytes)
Canaliculi: networks of canals connecting osteocytes; provide routes for nutrients and waste
Central canal: contains blood vessels and nerves
Spongy bone components
Made up of thin columns of bone (trabeculae), spaces between which are filled with red bone marrow; lacks osteons
Bone CT function
Support, protection, storage; houses blood-forming tissue; levers acting with muscle CT for movement
Formation of osteons
Mesenchymal stem cells (osteogenic) develop and starts to lay down collagen, become trapped and turn into osteoblasts;
osteoblasts lay down more collagen (ECM), mineralisation (ECM hardening) occurs; osteoblast matures due to being trapped in ECM and becomes osteocyte, maintain bone tissue, have gap junctions and involved in nutrient and waste exchange
Osteoclast
Large, multinucleated cell formed from fusion of blood monocytes; break down bone to produce Ca and P; allow production of new bone
Liquid CT types
Blood and lymph
Blood CT
Liquid containing liquid ECM made up of blood plasma (mostly water with dissolved substances), RBCs, WBCs and platelets
Where is blood CT found?
Within blood vessels and the heart
Blood CT function
RBCs: transport oxygen and carbon dioxide
WBCs: carry on phagocytosis and mediate allergic reactions and immune responses
Platelets: blood clotting
Types of WBCs (6)
Neutrophils and monocytes are phagocytic (engulf bacteria)
Basophils (mobile) and mast cells (immature circulate and mature fixed) (release substances to intensify inflammatory reaction)
Eosinophils (parasitic and allergic responses)
Lymphocytes (immune response)
Lymph CT
ECM fluid which flows in lymphatic vessels; contains several cell types in clear liquid ECM
Muscle tissue description and function
Consists of elongated muscle fibre cells (myocytes) that can use ATP to generate force via hydrolysis; provides body movements and protection, maintains posture and generates heat
Types of muscular tissue
Skeletal, cardiac and smooth
Skeletal muscle tissue
Long, cylindrical, striated fibres that vary in length; multinucleated cell with nuclei at periphery; considered ‘voluntary’ as it can be made to contract or relax by conscious control - not always voluntary (posture)
Longest muscle
Up to 60cm long, the sartorius; flexes hip up, abducts it and moves it out slightly, laterally rotates it
Smallest muscle
Stapedius, 1.25mm long; stabilises the smallest human bone (stapes) in the ear; changes tension on bones that conduct sound from the eardrum, reduces volume by tightening
Where is skeletal muscle found?
Attached to bones by tendons
Skeletal muscle function
Motion, posture, heat production and protection
Skeletal muscle components
Made up of myofibrils which fill the sarcoplasm (cytoplasm) of fibre and extend its entire length; comprised of thin filaments (made of actin) and thick filaments (made of myosin) which are contractile portions of the muscle and are separated into sarcomeres
Striations
Banding in the cardiac and skeletal fibres due to the highly organised structure of myofibrils where thin and thick filaments join together (overlap in some portions and not in others)
A-band in myofibril sarcomere
The dark, middle part running the length of the thick filaments; contains two overlap zones of thick and thin filaments
I-band in myofibril sarcomere
Light areas containing only thin filaments; no overlap zones and so no thick filaments
Z-disc in myofibril sarcomere
Link filaments of adjacent sarcomeres together, passing through centre of I-bands; made up of actinins
M-line in myofibril sarcomere
Circular supporting structure in the middle of sarcomere which holds thick filaments together; gives sarcomeres their structure by maintaining correct orientation
Titin in myofibril sarcomere
Links Z-disc to M-line; provides resting tension in I-band, molecular spring
CT of skeletal muscle
Epimysium, perimysium and endomysium
Epimysium
Surrounds anatomical muscle (dense irregular CT); allows movement, improves contraction efficiency and provides structure
Perimysium
Around fascicles/muscle bundles, each of 10-100+ muscle fibres (dense irregular CT)
Endomysium - where is it found?
Around muscle fibres, separating them from each other (areolar CT)
Cardiac muscle tissue
Striated, branched cells with single central nucleus, involuntary control; fibres join end-to-end through intercalated discs
Intercalated discs in cardiac muscle tissue
Contain desmosomes which strengthen tissue (bind intermediate filaments) and hold fibres together during contractions and gap junctions which provide passage for coordinated muscle action potential (electrical signals) conduction throughout heart
Where is cardiac muscle tissue found?
Heart wall
Cardiac muscle tissue function
Pumps blood to all parts of body
Where is smooth muscle tissue found?
Walls of hollow internal structures (blood vessels, lung airways, stomach, intestines, gall bladder, urethra and uterus); iris of eye
Where is smooth muscle tissue found?
Walls of hollow internal structures (blood vessels, intestines, skin)
Smooth muscle tissue structure
Bundles of thick filaments (myosin) and thin filaments (actin); thin filaments attach to ‘dense bodies’ (similar function to z-discs; actinin); dense bodies interconnected by intermediate filaments (non-contractile)
During contraction, tension transmitted to intermediate filaments and cell twists about dense bodies
Skeletal muscle tissue structure
Anatomical muscle (covered by epimysium) contains many fascicles (covered by perimysium); fascicles made up of many muscle fibre cells (covered by endomysium called sarcolemma) which contain myofibrils made up of myofilaments
Nervous tissue
Made up of neurons and neuroglia; subdivided into the CNS and PNS
Neurons function, types and components
Nerve cells that can be very large; do not divide, have a high metabolic rate and die rapidly without oxygen; multipolar, bipolar and unipolar; conscious and unconscious control; sensitive to various stimuli which they convert into nerve action potentials (electrical signals) and conduct them to other neurons, muscle tissue or glands; consist of a cell body, dendrites and axons
Nerve action potentials and how they move
NAP; electrical signals which move along the neurons’ surface membranes; conveyed by dendrites and conducted to other nerves/tissues by axons
Dendrites
Tapering, highly branched and usually short extensions; receiving/input part of neuron
Neuroglia description and function
Found in the CNS and PNS; smaller than neurons; can communicate by chemical means and divide within the mature nervous system
The physical structure and repair framework of nervous tissue; undertake phagocytosis, nutrient supply to neurons; regulate interstitial fluid in neural tissue
Axons
Single, thin, cylindrical processes that may be very long; output portion of neuron which conducts nerve impulses towards another neuron or tissue
Multipolar neurons
Have 2 or more dendrites with a single axon; most common neuron in CNS and include all motor neurons
Bipolar neurons
Singular dendrite process entering cell body (can branch out at tip) and 1 axon; cell body is between dendrite and axon; rare and small; found in special sense organs (relay information from receptor to neurons or relay information between different cells)
Unipolar neurons
Dendrites and axon are continuous (in one place); cell body is off to one side; site of dendrite convergence is the axon; most sensory nerves; very long
Neuroglia
Smaller than neurons and more abundant; found in PNS and CNS; can divide and communicate but cannot propagate NAPs; maintain structure and repair framework of nervous tissue, undertake phagocytosis, supply nutrients to neurons and regulate interstitial fluid in neural tissue
CNS neuroglia types
Astrocytes, oligodendrocytes, microglia and ependymal cells
Astrocytes (CNS neuroglia) function
Support; repair; communicate with neurons via ‘gliotransmitters’; maintain environment around neuron (regulate ions); maintain and form blood-brain barrier via endothelium, wrap around vessels and influence their permeability
Astrocytes (CNS neuroglia) function
Support; repair; communicate with neurons via ‘gliotransmitters’; maintain environment around neuron (regulate ions); maintain and form blood-brain barrier via epithelium, wrap around vessels and influence their permeability
Oligodendrocytes (CNS neuroglia)
Similar to astrocytes but smaller and simpler
Oligodrendrocytes (CNS neuroglia) function
Form insulating multilayered myelin sheath (protein lipid layer; extension of membrane and some cytoplasm of cell) around CNS axons of some neurons; can myelinate more than one neuron cell’s axon which accelerates action potential
Microglia (CNS neuroglia) and function
Small, slender processes; perform phagocytosis to remove broken-down tissue or bacteria that may invade into CNS; protection
Ependymal cells (CNS neuroglia)
Single layer of predominantly cuboidal cells with cilia and microvilli; located in ventricles (gaps in brain) and in the central canal of spinal cord; found wherever cerebrospinal fluid is
Ependymal cells (CNS neuroglia) function
Produce, monitor and assist in the movement of cerebrospinal fluid (CSF) - which is a mechanical buffer that moves nutrients and waste, is a nutrient source for the brain
PNS neuroglia types
Schwann cells and satellite cells
Schwann cells (PNS neuroglia) and function
Small cells which encircle PNS axons; PNS version of oligodendrocyte (myelination); forms insulating myelin sheath around axons or can just support and surround several non-myelinated axons
One axon per cell for myelination but more axons per cell for support
What is the difference between proteoglycans and glycoproteins?
Both are molecules containing proteins and sugars. Proteoglycans contain more sugars and glycoproteins contain more proteins.
What is the difference between proteoglycans and glycoproteins?
Both are molecules containing proteins and sugars. Proteoglycans contain more sugars and glycoproteins contain more proteins.
Membrane types
Mucous, serous and cutaneous (epithelial) and synovial (contains CT and no epithelium)
Mucous membrane
Epithelial; lines a body cavity which opens directly to exterior; consist of a lining layer of epithelium and an underlying layer of CT; tight junctions connect the cells and contains goblet cells; epithelia of membrane can differ in different parts of body; areolar CT (lamina propria)
Where is mucous membrane found?
Lining of entire digestive, respiratory and digestive tracts and much of urinary tract
Mucous membrane function
Barrier which protects against microbes and other pathogens; goblet (and other cells) secrete mucous which prevents drying out of cavities, traps particles and lubricates food; secretes digestive enzymes and provides site for food and fluid absorption (gastrointestinal tract); CT supports epithelium, binds it, allows flexibility, holds blood vessels in place and is vascular source for membrane
Serous membrane
Epithelial; line body cavity which does not open directly to exterior; covers organs within cavity; consists of areolar CT covered by mesothelium; have 2 layers: parietal (attached to and lining cavity wall) and visceral (covers and adheres to organs within cavity)
Where serous membrane found?
Lining thoracic cavity and covering lungs (pleura), lining heart cavity and covering heart (pericardium), lining abdominal cavity and covering abdominal organs (peritoneum)
Serous membrane function
Secretes serous fluid (watery lubricant) which allows organs to glide easily over one another or slide against the walls of cavities
Cutaneous membrane
Epithelial; skin; consists of a superficial portion which consists of keratinised stratified squamous epithelium (epidermis) and a deeper portion which consists of dense irregular CT and areolar CT (dermis)
Where is cutaneous membrane found?
Covers entire surface of body
Cutaneous membrane function
Epidermis protects underlying tissues and dermis resists pulling and stretching forces
Synovial membrane
Line cavities (that don’t open to exterior) of freely moveable joints; lack epithelium; composed of discontinuous layer of cells and layer of areolar and adipose CT; secrete some components of synovial fluid which lubricates and nourishes cartilage covering bones at moveable joints and contains macrophages which remove microbes and debris
