Tissues Flashcards
what is 5 functions of bone in vertebrates
”- Support: maintains upright posture
- Protection: protects the brain and internal organs
- Movement
- produces red blood cells
- stores minerals and fats”
what are the 3 types of cartilage and where are they found
”- Hyaline: surfaces of joints
- Fibrous: menisci of synovial joints
- Elastic cartilage: - ear flaps and larynx”
whats the function of cartilage
”- Structure and support to other tissues
- Cushions joints and smooths movement of joints
- ESSENTIAL for development of long bone”
whats the outer layer of cartilage called
perichondrium
what are the 2 layers of cartilage
”- Fibrous layer
Chondrogenic layer
What are the features of fibrous layer of cartilage
contains fibroblasts that produce collagenous fibres
Also contain blood vessels which supply the cartilage with nutrients and oxygen
What are the features of chondrogenic layer of cartilage?
– Remains undifferentiated and can form chondroblast”
what is ossification
the process of forming bone
why are chondroblasts important?
“Chondroblasts secrete a substance called Extracellular matrix
Chondroblasts mature into chondrocytes”
what is direct ossification
”- intramembrane
-Mesenchymal cells → bone
e.g. Flat bones of skull
(primary bone formation in first 2 months)”
what is indirect ossification
“-Endochondral
- Mesenchymal cells → Cartilage → Bone
- bone formation after 2 months
- Most of the bones of the skeleton are formed in this manner”
what is the chemical composition of bone
“organic = 1/3 of mass
- OSTEO cells
- matrix- collagen - strength to bone prevents it from brittleness
inorganic = 2/3 of mass
- inorganic mineral salts:
calcium phosphate
calcium hydroxide
calcium carbonate
- provides hardness
- bone is extremely strong but not brittle”
how are bones classified by shape
”- long
- short
- flat
- irregular”
what is the gross anatomy of a long bone
”- diaphysis - shaft
- epiphysis - end
- medullary cavity - canal
- periosteum - covering
- endosteum - canal lining
- articular cartilage - on endsof bones for smooth movement
- marrow
yellow - fat storage
red - blood cell formation”
what are 4 bone cells and their functions
“Osteoclast- resorbs bone (made from macrophage)
Osteogenic/ osteoprogenitor cell- stem cell
Osteoblast- forms bone matrix
Osteocyte- maintain bone tissue”
describe osteoblasts
Secrete OSTEOID: collagen and non-collagen proteins + calcium binding protein osteocalcin. the osteoblasts become TRAPPED in the matrix. Mature into osteocytes.
describe osteocytes
Mature bone cells Are unable to undergo cell division Are networked to each other via long cytoplasmic extensions that occupy tiny channels called canaliculi used for exchange of nutrients and waste
describe osteoclasts
“Different cell line from the other cells. Actually from monocytes (white blood cells). Multinuclear giant cells – fusion of many cells. Ruffled border – facing towards bone (SA – resorption).
- They secrete acid and enzymes (acid phosphatase) to breakdown bone tissue
- Dissolve bone
- Release calcium and phosphate yo replace old with new
- To change the shape of bone in response to stress
- Hormones
PTH – increase activity (increase plas. Ca2+)
Calcitonin – decrease activity”
why is bone remodelling important
“1. Homeostasis – maintaining plasma Ca2+ levels in your plasma
2. Removing old damaged tissue and replacing it with new. E.g, breaking a bone, the formation of a bone callus and then shaving away that callus”
sytructure of compact bone
“Compact:
made up of osteons
- cement layer
- lamalle
-haverisan canal
-canalicculi
lacuna
structure of spongy bone
Spongy:
- honeycomb structure
- -Spaces often filled with red bone marrow
- No Haversian system
- no central canals, no perforating canals
- There are blood vessels but they are found in the spaces between the trabecullae
- Nutrients are able to diffuse through the tissue via extracellular fluid”
what are 5 functions of blood
”- Transport: including nutrients, gases, wastes
- Temperature Regulation: by altering blood flow through the skin
- Immunity: protection against pathogens
- Communication: hormones
- Defence: clotting following a wound”
what is the composition of blood
”- plasma (55%)
- red blood cells- eryth
- white blood cells- leuco
- platelets - thrombo”
what is haematpoiesis
the process of blood cell production
where is blood formed in the fetus vs in adults
“in the fetus: liver and spleen and from bone marrow
in adults: rbc/granular leucocytes/platelets produced in red bone marrow, leucocytes produced in myeloid tissue (red bone marrow) & some mature in lymph tissue”
RBC: Structure
- biconcave disc that is round and flat without a nucleus, mitochondria and endoplasmic reticulum
- contain haemoglobin which combines with oxygen at high partial pressures of oxygen
- can change shape without breaking
- Diameter 7μm
RBC; Function
- Carry oxygen in the form of oxyhaemoglobin. Each Hb molecule carries eight atoms of oxygen
- Hb readily combines with oxygen when oxygen is at a high concentration eg. lungs
- Hb releases oxygen where it is at a low concentration eg respiring tissue- muscles
- also carries carbon dioxide
some non-mammalian animals may have nuclei, eg, fish
WBC function
- combat microbes either by phagocytosis or antibody production
name the 5 types of white blood cells (graular and nongranular) and describe their function and shape
“Granular
- neutrophils (multilobed nucleus)- phagocytosis
- Basophils: secrete heparin and histamine (least common) involved in allergic response
- Eosinophils: Combat parasitic infection/allergic response (pink/red granules)
Non Granular
- Monocytes: phagocytosis- When leave the bloodstream and transform within tissues = macrophages (one-legged horse)
- Lymphocytes:
T cell – adaptive immune response (cell-mediated immunity)
B cell –humoral immunity (relating to antibodies)
platelets: structure and function
”- In mammals they have no nucleus
- involved in haemostasis – by forming a platelet plug where fibrin allows platelets to aggregate together.”
Plasma Structure and function
”- straw-coloured liquid that carries the cells and the platelets which help blood clot
- also contains, carbon dioxide, glucose, amino acids, proteins and water (90%) etc”
- contains the proteins Albumin (maintains osmotic pressure), Globulin(Importants for immune response- antibody production), Fibrinogen (essential for blood clotting)
define homeostasis
“-Maintaining a stable environment within the body. Conditions that need to be controlled within limits include:
- pH
- Blood glucose levels
- Temperature control
- Water content
- Ion content”
what is the role of blood inn homeostasis
“role of blood in homeostasis
- Blood glucose levels are hormone controlled, (insulin & glucagon).
- Temperature control: vasodilation and vasoconstriction
- Water content: hormone control (ADH)
- Ion content: blood is filtered by the kidneys
- Maintaining blood pH (buffer system)”
what are 3 types of muscle
”- skeletal
- smooth
- cardiac”
function of muscles
”- movement- skeletal muscle contraction
- posture- continual adjustment of skeletal muscles
- protection- skeletal muscles in abdominal wall
- sphincter control- skeletal muscle control opening and closing of sphincters eg swallowing
- movement along gi tract- smooth muscle generates peristalsis
- Temperature regulation- shivering, skeletal muscle”
describe the function of skeletal muscle
”- voluntary control
- striated appearance
- not electrically connected, each needs to receive a nerve impulse to contract unlike cardiac and smooth
- attached to bone by tendons”
structure of skeletal muscle
”- muscle fibres (myocytes) are classified as cell- multi nuclei, large, long, many mitochondria
- myofibrils are organelles each contaisn many myofilaments (actin myyosin)
- sarcolemma = plasma membrane contains t tubules
- sarcoplasmic reticulum- endoplasmic reticulum
- T tubules store calcium ions
- Repeating units of overlapping actin and myosin filaments are organised into sarcomeres”
describe the neuromuscular junction
”- specialized form of synapse that forms between a neurone and myofibril.
- some motor nuerones only affect one cell while others branch to NMJs causing a cluster of muscles fibres to contract
- action potrntial travels down motor nuerone to muscle which triggers Ach to diffuse across the synapse and causes contraction”
steps of muscle contacion
“1. Calcium ions bind to troponin on actin filament, changes its hape which pushes away tropomyosin, exposing myosin binding sites.
2. Myosin binds to the exposed Myosin binding sites on the actin forming a ‘cross-bridge’.
3. the myosin heads tilts backwards, pulling the actin filament past the myosin filament ‘the power stroke’. (ADP and Pi are released)
4. A new ATP molecule attaches and breaks the cross bridge
5. The myosin head swings back forwards and is ready to bind to another binding site further along the actin”
describe the structure of smooth muscle
”- Smaller than skeletal or cardiac myocytes
- Not striated – myofilaments not arranged in sarcomeres
- Less regular – spindle shaped
- Mononuclear
- No T-tubbules
- Not attached to bone”
where can smooth muscle be found
“-Involved in internal transport
- walls of uterus
- walls of digestive tracts
- blood vessel walls”
how does smooth muscle function
”- Involuntary contraction
- Stimulated by the autonomic nervous system, hormones and in response to stretch
- Slower than skeletal muscle but able to hold for longer
- Less cross-bridges are formed, but for a longer duration*
- Maximum contractile force is the same
- ATP generation is mainly via oxidative phosphorylation”
describe cardiac muscle
”- Involuntary muscle contraction
- Striated muscle
- ATP generated by oxidative phosphorylation
- Branched
- Intercalated disks”
what are sarcomeres
Repeating units of overlapping actin and myosin filaments are organised into sarcomeres
what are the 2 types of muscle fibre and describe them
- Fast twitch
- slow twitch
describe fast twitch muscle fibres
Fast twitch
- Short term
- Fast contraction velocity
- Large diameter
- Increased CP
- More anaerobic production of ATP
describe slow twitch muscle fibres
slow twitch
- Endurance
- More blood capillaries
- Increased myoglobin
- More aerobic ATP production
