Week 8 Flashcards
What are the key functions of blood?
Distribution (gases, nutrients, waste)
Regulation (Temp, pH, fluid vol)
Protection (against haemorrhage (fibrinogen), against infection (leukocytes/wbc))
What is an erythocyte?
Red blood cell
What are the formed elements of blood?
8% total body mass = blood (5L)
Erythrocytes (RBC)
Leukocyes (WBC)
Thrombocytes (Platelets)
(blood also contains Plasma)
What are Leukocytes?
White blood cells
What are thrombocytes?
Platelets
What are the different types of white blood cells?
Neutrophils (60-70%,
Lymphocytes (20-25%),
Monocytes(3-8%),
Eosinophils (2-4%),
Basophils (0.5-1%)
What is haemopoiesis (or haematopoiesis)?
The production of all formed elements of the blood
What are the 7% of proteins that make up plasma?
Albumins (54%
Globulins (38%)
Fibrinogen (7%)
Others (1%)
What does Eosin, methylene blue and wrights stain stain?
Eosin = basic/alkali components (red)
Methylene blue = acidic components (blue)
Wright’s stain = eosin + methylene blue
what is erythropoiesis?
Formation of RBC occurring in the red bone marrow
What does erythropoietin do?
Stimulates erythrocyte formation, produced in the kidney
Features of Erythrocytes?
Anuclear
Biconcave shape
Haemoglobin (33% of weight)
Oxygen transport/CO2 removal
Make 2 million/second
Last approx. 120 days
What are the stain characteristics of Leukocytes?
Basophils: Bilobed nucleus, blue granules (histamine)
Eosinophils: Bilobed nucleus, red granules (basic protein)
Neutrophils: Multi-lobed nucleus, few granules
Monocytes: Horseshoe shaped nucleus, large cells
Platelets: Not cells – no nucleus, small
What are the two categories of Leukocytes?
- Granulocytes
- Agranulocytes
(Function is to protect)
What are the three types of Granulocyte WBC?
Neutrophils,
Eosinophils,
Basophils
What is the role of eutrophils?
Phagocytes - Move to site of infection
What is the role of Eosinophils?
Allergic response and parasitic invasion
What is the role of Basophils?
Allergic, inflammatory response and parasitic invasion
What are the two types of Agranulocytes WBC?
Lymphocytes
Monocytes
What is the function of Lymphocytes?
Immune response
T-lymphocytes
B-lymphocytes (differentiated into Plasma Cells that produce antibodies)
What is the function of monocytes?
differentiate into macrophages
Phagocytes and can recruit other elements of immune system
How are platelets produced, what is their function.
contain clotting/coagulation factors
Cytoplasm of Megakaryocyte pinched off to produce platelets (2-3 micrometres diameter)
What is Haemostasis?
Refers to a sequence of responses to stop bleeding - if unsuccessful results in haemorrhage.
What are the 3 stages of haemostasis?
(More detail on L6 recording)
1 - Vascular spasm
2 - Platelet Plug
3 - Blood clot formation
(Fibrinogen (soluble) converted to fibrin (insoluble threads))
What are the two forces involved in tissue fluid formation?
Hydrostatic pressure (pushing),
Osmotic pressure (pulling)
These dictate filtration pressure.
What is the next result of filtration pressure per day?
approx. 20 litres/day from blood stream into tissue and 17 litres from tissue into blood stream (other 3 litres = Lymph)
How does fluid move into the tissue during tissue fluid formation?
Proteins and ions give the blood a relatively high osmotic pressure - likely to drag water into the blood
At the arterial end of the capillary the high hydrostatic pressure overcomes this osmotic pressure and fluid (along with nutrients and gases) moves into the tissue
Summary of Filtration pressure (tissue fluid formation)?
Overall movement of fluid is determined by the FILTRATION PRESSURE
At arterial end:
- Filtration Pressure is positive
- Fluid passes from the blood to the tissue fluid
At the venous end:
- Filtration Pressure is negative
- Fluid passes from the tissue fluid to the blood
What is the relationship between lymph and blood vessels?
Lymph accounts for the 3 litres of fluid not reabsorbed
Lymphatic vessels transport lymph from tissue spaces to veins
Lymph drains into the circulatory system via lymphatic ducts located in veins near the heart
Give examples of some clinical blood abnormalities?
Thrombocytopenia
Haemophilia
Thrombophilia
Deep Vein Thrombosis (DVT)
Sickle cell disease (SCD)
Disseminated intravascular coagulation
Hemochromatosis
Myeloproliferative disorders
Septicaemia
Embolism
What is skeletal muscle also known as? Why?
Voluntary muscle
Its under conscious control, and usually connected to skeletal system by tendons (made from collagen)
What are the 6 functions of skeletal muscle?
Movement (by pulling on bones to make the skeleton move)
Maintain posture
Support for soft tissues
Control of ‘openings and exits’ (e.g. conscious control of urination, defecation, swallowing.)
Maintenance of body temperature (muscles use energy and some is converted to heat)
Nutrient reserve
How are muscle fibred bundled together?
Muscle fibres are wrapped in the endomysium, which is wrapped by perimysium forming the fascicle. Held altogether by the epimysium, connected to the bone via a tendon
What are skeletal muscle fibres formed from?
Several myoblast cells fuse early in development to form a muscle fibere
How are myofibrils formed?
comprised of many myofilaments, (thick and thin filaments) arranged into sarcomeres.
A muscle fibre contains many myofibrils
What is the multinucleate in muscle fibre?
nuclei located under sarcolemma (plasma membrane)
Why do muscle fibres appear striated (striped)
Because of aligned sarcomeres
What are myofibrils surrounded by?
sarcoplasmic reticulum (endoplasmic reticulum) which stores Ca2+
What transfers action potential to the myofibrils?
T-tubules
This can then transfer to the sarcoplasmic reticulum which releases the action potential as Ca2+
What filaments do myofibrils consist of?
Thick and thin myofilaments arranged into sarcomeres (about 10,000 arranged end-to-end).
Thin filaments = actin
Thick filaments = myosin
What is the M-line?
Sarcomere bands/zones
Middle line - attaches thick filaments together
What is the A band?
Sarcomere bands/zones
Dark bands, contain myosin + actin
What is the I band?
Sarcomere bands/zones
Light band, contain only actin
What is the H band?
Sarcomere bands/zones
Contain only myosin
What is the Z line (Z disk)?
Sarcomere bands/zones
Joins adjacent sarcomeres (a-actinin)
What is the zone of overlap?
Sarcomere bands/zones
Region where actin and myosin overlap
How does a sarcomere contract?
Sliding filament model of contraction
Thick (myosin) filaments interact with thin (actin) filaments and pull the thin filaments towards the M line
How are thick muscle filaments made?
Made of myosin.
Many myosin molecules wound together = thick filaments.
Contraction - thick filaments interact with think filaments
What is the role of titin in muscle contraction?
Prevents over-extension of sarcomere
What are thin filaments made of?
Actin
Regulatory protein attached (troponin, tropomyosin)
How can myosin bind to actin during contraction, when the myosin binding site on actin is covered by tropomyosin?
When stimulated to contract, calcium (Ca2+) enters the muscle
Calcium binds to troponin which causes tropomyosin to uncover myosin binding sites on actin.
Myosin can now bind to actin and cause contraction.
Sliding filament theory step 1?
Action potential arrives causing release of calcium
Calcium ions bind to troponin so tropomyosin moves and uncovers myosin binding site on actin
Sliding filament theory step 2?
Crossbridge formation - myosin binds to actin
ADP and phosphate are still attached
Sliding filament theory step 3?
The Power Stroke.
ADP and phosphate are released so the myosin head bends, pulling actin
Stored energy in myosin head is released and myosin head pivots.
Sliding filament theory step 4?
The cross bridge breaks because ATP binds myosin head, causing it to detach from actin.
Sliding filament theory step 5?
Myosin Reactivation - myosin head splits ATP into ADP+Pi so myosin head ‘re-cocked’ ready for another contraction cycle if calcium is still present.
What triggers muscle contraction to stop
As the Ca2+ levels have decreased, as Ca2+ returns to the sarcoplasmic reticulum
How does the contraction cycle end?
Acetylcholine (ACh) broken down in synaptic cleft by acetylcholinesterase
Calcium no longer released from sarcoplasmic reticulum
Calcium ions are pumped from the cytoplasm, back into the sarcoplasmic reticulum
Calcium detaches from the troponin complex on actin, so tropomyosin covers myosin binding sites, preventing muscle contraction.
Bone cannot perform its function without what other tissues along side it?
Ligament,
Synovium,
Hyaline Cartilage
Fibrocartilage
Muscle
Tendon
What is formed where two bones come together?
A joint
What does ligament do?
Holds two bones together
What does highline cartilage do?
Its on the ends of bones, and provides a really smooth friction free surface for the bones to move against each other
What happens when hyaline cartilage goes wrong?
Could end up with diseases such as osteoarthritis
What is fibrocartilage?
Tough, acting as a shock absorber.
What structures attach bone?
Ligaments = bone to bone
tendons = muscle to bone
Ligaments function to what? While tendons function to what?
Ligaments: Limit movement of bones
Tendons: Enable/facilitate movement of bones
Major mechanical function and composition of ligament?
resist tension
collagen I
Major mechanical function and composition of tendon?
resist tension
Collagen I
Major mechanical function and composition of cartilage?
resist compression (and tension)
Collagen II
Proteoglycan
Water
Major mechanical function and composition of fibrocartilage?
Resist compression and tension
Collagen I and II
Proteoglycan
Water
Major mechanical function and composition of bone?
resist compression (and tension)
collagen I
mineral (hydroxyapatite)
Major mechanical function and composition of synovium?
lubrication
mainly cellular
how many bones are in the adult skeleton?
206
how many bones are in a neonate?
300
What is the importance of epiphyseal growth places on bones?
What are known as physical growth plates, they enable our bones to grow in size
What are the three layers to our body? What do these produce?
Endoderm (produce epithelial cells)
Ectoderm (produce nerve tissue, epithelial cells)
Mesoderm (produce connective / muscle tissue and epithelial cells)
What two processes enable humans to get bone?
Mesoderm forms connective tissue, which by endochrondal ossification or intramembranous ossification forms bone
What is endochondral ossification?
Most of our bones develop from this process.
Fetal skeleton (cartilage), –> blood vessels invade the cartilage –> cartilage skeleton ossifies to become bone Some take 25yrs to fully complete this process
How does bone form from cartilage during endochondral ossificatiom?
Chondrocytes that live in cartilage don’t like blood, so cartilage doesn’t have a blood supply, and when blood vessels invade it they begin to undergo cell apoptosis and bone cells replace them
What is intramembranous ossification
Begins as mesenchyme –> bone.
No cartilage seen.
Cells proliferate and condense.
What bones usually form from intramembranous ossification?
Flat bones eg in the skull
What are long bones composed of?
A cylindrical shaft (diaphysis) connected to the expanded ends of the bone (epiphyses)
What are the four major categories of bone?
Long bone (eg humerus, femur, tibia, fibula, radius, ulna)
Short bone (carpal (wrist) bones eg hamate, trapezoid, scaphoid. Tarsal (ankle) bones eg talus, calcaneous)
Flat bones (eg bones in the skull)
Irregular bones (eg vertebra clusters)
Other than the four major bone categories, what bone doesn’t fit these?
Sesamoid bones - or patella (knee caps)
Mechanical functions of bone?
protection,
Support for organs (structure),
A system of levers (movement)
What are metabolic functions of bone?
Store for minerals (especially Ca and metals (detoxify the body by holding metals)),
Hemopoiesis/haematopoiesis (red marrow where blood cells are made)
An endocrine organ (produces signalling molecules that has actions in organs)
Is bone a living tissue?
Yes. Our skeleton changes as we age
What are the four main cell types of bone?
Osteoblasts - Ob (for building)
Osteocytes - Oc (For maintaining, tell body if we need or don’t need bone)
Lining cells - Lc (For maintaining surfaces of bone)
Osteoclasts - Ocl (For removal)
Bone cells: osteoblasts?
Build bone
Synthesising bone matrix and priming it for subsequent mineralisation
They are plump cuboidal cells with abundant organelles for synthesis and secretion of protein
Form an epithelioid layer on the bone surface
Bone cells: osteocytes formation?
Osteoblasts engulfed in bone matrix during apposition and entombed within bone matrix (form osteocytes)
Bone cells: lining cells formation?
Osteoblasts that have completed phase of synthetic activity, but can be reactivated and be osteoblasts again (after having a rest)
Bone cells: osteoclasts?
Large multinucleate cells responsible for resorption of bone.
Distinctive appearance and contains unique organelles, the ruffled border and clear zone
Overtime what do osteoblasts become?
osteocytes
Osteocytes reply on what to maintain junctions with other entombed osteocytes and with the bone surface, and hence to the vascular supply?
Canaliculi
Bone cells: osteocytes function?
Regulation of calcium homeostasis and also act as a strain gauge to monitor and record the extent of physical loading
What is the function of lining cells? (bone cells)
Activation of bone remodelling and probably co-operate with osteocytes in regulating calcium exchange from bone
Bone matrix is a composite of?
Type I collagen, bone proteoglycan and some non-collagenous proteins (osteoclacin, osteonectin, osteopontin)
Mineral, hydroxyapatite, a complex calcium phosphate salt.
What is the formula for hydroxyapatite?
Ca10(PO4)6(OH)2
How are bones demineralised?
By removing the mineral component, which makes the bone very bendy
What happens if collagen is removed from the bone?
Anorganic bone
Makes the bone very brittle like a meringue
What are the two forms bone is organised into?
Compact bone (high proportion of bone with few spaces)
Cancellous, spongy or trabecular bone (low proportion of bone and lots of spaces)
Cancellous bone is composed of what?
A network of rods and plates called trabeculae
How can we change and alter our skeleton (bone structure) ?
We can renew the model in processes depending on what strains and stresses we put on it.
In old age, our skeletons will waste away due to the loss of oestrogen throughout life
How do oestrogen and testosterone play a part in bone structure/shape?
Kill the cells that eat bone away and stop it from getting too out of hand. When ladies go through menopause, they stop producing oestrogen, so the osteoclasts eat away more bone than we can renew - Hence the development of osteoporosis in elderly women
What is bone remodelling?
A cyclical process:
Resting –> Activation –> Resorption –> Reversal –> Formation –> Resting
Evidence of bone and cartilage adapting?
When someone is in space they lose about 40% of their bone mass and muscle, hence why they continuous exercise while on the space station
Tennis players have thicker bone mass in the right hand than the left.
Fracture repair stages?
Haematoma formation
Soft callus formation
Hard callus formation
Bone remodelling
Fracture repair: haematoma formation?
(scab-like formation to stop haemorrhage)
Fracture repair: Soft callus formation
(Collagen is being laid down by cells to try attach the two ends of bone)
Fracture repair: Hard callus formation
Collagen is mineralised
Fracture repair: Bone remodelling
The last stage of fracture repair, but more bone is being made than lost
(other flashcard has bone remodelling stages)
