7 Bone Flashcards by Mai O

Different types of bone

Long e.g.) humerus
Short e.g.) trapezoid, calcaneus
Flat bone e.g.) sternum, ilium, occipital, ribs
Irregular bone e.g.) vertebrae, sacrum
Sesamoid bone e.g.) patella

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Function of long bones

Supports the weight of the body and facilitate movement

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Function of short bones

Provide stability and some movement

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Function of flat bones

Protects internal organs
Provide large areas of attachment for muscles

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Function of irregular bones

-Protect internal organs
e.g.) protects spinal cord, organs in pelvic cavity

-Provide important anchor points for muscle groups

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Structure of Sesamoid bones

Small, round bones found in the tendons of hands, knees, and feet

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Function of Sesamoid bone

Protect tendons from stress and damage from repeated ‘wear and tear’

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Where are the long bones mostly located in

Appendicular skeleton

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Osteomyelitis

Infection within bone

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Osteosarcoma

A cancer originating from bone forming cells

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How many bones does the skeleton have

206

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Name the bones of the axial and appendicular skeleton

Axial: Head, vertebrae, ribs (80)
Appendicular: Shoulder girdle, upper limbs, pelvic girdle, lower limb (126)

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Functions of bone

-Mechanical (protect delicate organs, provide framework)
-Synthetic (Haemopoiesis)
-Metabolic (mineral/fat storage, acid-base homeostasis)

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Describe the difference between Cancellous and Compact bone

Cancellous:
-trabeculae (combines strength with lightness)
-spaces are filled with by bone marrow

Compact:
-forms external surfaces of bones
-80% of skeletal mass

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Describe endochondral ossification

Formation of long bones from hyaline cartilage

-continued lengthening is by ossification at epiphyseal plates
-e.g.) appositional growth (at edges)

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Describe intramembranous ossification

Condensations of mesenchymal tissues from flat bone
-cancellous bone
-e.g.) interstitial growth (in the middle)

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How do bones undergo remodelling

Osteoclast: bone reabsorption

Osteoblast: remaking bones
-RANK L (initiated remodelling)
-osteoprotegerin (turns off remodelling)

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Composition of bone in terms of its cells & extracellular components

Bone marrow
-red marrow (haemopoiesis)
-yellow marrow (energy source)
-BV
-Nerves

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Difference between Cancellous bone and Compact bone

Cancellous bone:
-composed of trabeculae
-no nerves, lymphatic/blood vessels

Compact bone:
-composed of osteons
-Haversian canal, Volkmann’s canal

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How is Cancellous bone converted to Compact bone

MSC convert into osteoblast
Osteoblast lays down osteoid that is mineralised
Osteoblasts are trapped = Osteocytes
Repeat of 1~3
Central MSC converts into blood/lymphatic vessels, nerves

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Importance of Vitamin D in normal bone stability

Produces calcitriol (calcium absorption)
-either absorbed from gut or synthesised in the skin

Two steps involved in bone-remodelling

Osteoclasts make a wide tunnel in the bone (cutting cone)
Osteoblasts make a smaller tunnel of compact bone (closing cone)

Why do the main force lines go through the cortical/compact bone

Lamella (structure in compact bone) are thought to be able to slip relative to each other to resist fracture

Factors affecting bone stability

-activity of osteocytes (osteoid recycling)
-activity of osteoblasts (bone deposition)
-activity of osteoclasts (bone resorption)
-nutrients (vitamin D3, C, K, B12)

Importance of Vitamin C in bone stability

Synthesis of collagen

Function of osteoid

Undergoes calcification and mineralisation to form lamellae or layers in the bone matrix

Importance of Vitamin K and B12 in bone stability

Synthesis of bone proteins

Importance of Vitamin D3 in bone stability

Produces calcitriol (calcium absorption) -either absorbed in gut/synthesised in skin

Constituents of bone marrow

Haemopoietic cells -myeloid -lymphoid lineages Marrow adipose tissue Supportive stromal cells

In what parts of an adult body can bone marrows be found

Ribs Vertebrae Sternum Bones of the pelvis

Functions of the bone marrow

-Used to treat severe diseases e.g.) leukaemia -Bone marrow stem cells can be transformed into functional neural cells and can potentially be used to treat inflammatory bowel disease

Constituents of blood and its classification

Loose connective tissue -Formed elements (i.e. blood cells, platelets) -Liquid phase (plasma)

3 major groups of blood vessels

1. Arteries and arterioles 2. Capillaries 3. Vein and venules

Key arteries in the body

Aorta Brachiocephalic trunk (supplying head, neck, upper limb) Carotid arteries (head, neck) Subclavian arteries (upper limbs) Iliac arteries (lower limb) Pulmonary arteries

Conducting arteries

The key, large arteries in the body that transport blood away from the heart towards the distributing arteries (medium sized arteries)

Which artery contain deoxygenated blood

Pulmonary artery

Which veins contain oxygenated blood

Pulmonary veins Umbilical vein

Constituents of the medulla region of long bones

Adipose tissue (contains stem cells that can become cartilage, fat, bone cells)

What are the different types of vein

-Pulmonary veins (carry oxy. blood from lung to LA) -Systemic veins (return oxygen-depleted blood from the rest of body to RA) -Superficial veins (surface of the skin) -Deep veins (located near a corresponding artery with the same name) e.g.) femoral artery and vein

Function of collateral blood vessels

Provide protection for tissues that may become compromised -alternative path for arterial blood flow

When are collateral blood vessels formed

-Chronic diseases e.g.) ischaemia, atherosclerosis -Produced during development (e.g. brain and joints)

Describe Vasculogenesis

Formation of new blood vessels from angioblast precursors (bone marrow) e.g.) embryo development, new cancers, endometriosis

Describe Angiogenesis

Formation of new blood cells from existing blood vessels e.g.) fetal development, collateral arteries, postnatal lung dev.

Two types of Vasculogenesis

Production of single vessel (VEGF, generates primary plexus, which folds into a primary vessel) 1. Sprouting: Angiogenesis -FGF -Pericytes convert into SMC -slow 2. Division of primary vessel: Intussusception -Twinned vessels from primary vessel -Multiple GF -Quick -Explains neurovascular bundles

Function of pericyte

-Prevents endothelial cell proliferation -Maintains tight capillaries e.g.) blood, brain barrier, in the retina

Features of pericyte

-Immature 'smooth muscle-cell like' cell -Found inside the basal lamina -Key component of capillaries -Contractile properties -Nerve cell communication -Able to differentiate into endothelial cell, SMC, fibroblast

During human development, when does the sesamoid bone first appear

Post-natal period

Where is the osteoprogenitor cell found

Periosteum under the connective tissue layer (some on the endosteum)

Function of canaliculi

Movement of nutrients

Ossification centre in the diaphysis

Primary ossification centre

Ossification centre in the epiphyses

Secondary ossification centre

What separates the ossification centres

Epiphyseal plates (growth plates)