Bone, Marrow, Vssels And Blood Flashcards
What types of bone excise in our body?
Long Short Flat Irregular Sesamoid (seed shape)
What is the structure of long bones? And what is their function?
Longer than they are wide
Femur = longest, fingers= shortest
Mostly found in appendicular skeleton
They support the weight of the body and facilitate movement
What is the structure and function of short bones?
Approximately as long as they are wide
Eg, wrist and ankle joints (Carpals in wrist, tarsals in ankle)
They provide stability and some movement
What is the structure and function of flat bones?
They are somewhat flattened with roughly parallel opposite edges
Skull (occipital), thoracic cage (sternum and rib), pelvis (ilium)
They protect internal organs
Provide large areas of attachments for muscles
What is the structure and function of irregular bones?
Vary in shape/structure so don’t fit into any other category
Often complex shape
Protect internal organs
Vertebrae protect spinal chord
Pelvis (sacrum) protect pelvic cavity organs
Provide anchor points for muscle groups
What is the structure and function of sesamoid bones?
They are embedded in tendons
Small, round bones found in tendons of hands, knees and feet
They are usually generated postnatally like the patella
They protect tendons from stress and damage, fro repeated wear and tear
What is cancellous bone? (Sometimes called spongy bone)
It’s in the middle of bones and forms a network of fine bony columns that combine strength and lightness.
In the spaces between these columns is filled with bone marrow.
What is compact bone? (Sometimes called cortical)
Forms the external surfaces of bones
Thin at head of bones, thick in the middle
Makes up 80% of the bones mass (heavy)
What are the 2 types of bone marrow and their functions?
Red-to replenish blood cells (haemopoiesis)
Yellow-shock absorber and energy source
Describe red bone marrow .
Full of developing blood cells
Rich blood supply
Only found in cancellous/spongy bone
Describe yellow marrow and state an unusual ability it has?
Full of adipocytes
Poor blood supply
Can convert to red blood marrow in anaemia (eg after severe blood loss)
In cancellous (spongy bone) what is a trabeculum and what is it made up of?
A bony structure or beam
It consists of numerous osteocytes embedded in the irregular lamella of bone.
Osteoblasts and osteoclasts on their surfaces remodel them.
What do osteoblasts do?
They make bone
They are regulated by hormones
What are osteoclasts?
They destroy/ remodel bone.
What do osteocytes do?
They recognise stress when it is placed upon the bone and send a message to osteoblasts to make more.
How do most maturing cells leave the bone?
The pass through sinusoidal cappilaries to join the blood stream.
These capillaries feed back into the central marrow vein which collects new blood cells and takes them out to the rest of the blood supply.
What methods do platelets use to exit the marrow?
They use megacryocytes.
How long does it take RBC’s to mature in the blood stream?
Around 2 days
However, during this time they are susceptible to damage and loss
How is capillary blood flow controlled?
Controlled by precapillary sphincters. (Small muscle)
They are between arterioles and capillaries and can contract to stop blood flowing through the capillary beds.
What is the function of precapillary sphincters?
They control fluid exchange between capillaries and body tissues which occurs at capillary bed
They mean that larger cells cannot pass through cappilaries so bypass the capillary bed (eg WBC’s)
What us the definition of a vein?
A vein is an elastic blood vessel that transports blood from various regions of the body TO the heart
What are the 3 layers that make up a vein?
Tunica intima = endothelial cells (inner layer)
Tunica media = elastic fibres and smooth muscle (middle layer)
Tunica externa = elastic fibrous capsule (external layer)
What helps blood return to the heart in veins?
Non-return fibroelasic cartilaginous valves assist flow to the heart
The low pressure system means veins rely on muscle contraction to help move blood to the heart (calf muscles compress to aid movement against gravity = muscle pump)
What are the 4 vein types?
Pulmonary
Systemic
Superficial
Deep
How are pulmonary veins categorised?
Carry Oxygenated blood from lungs to left atrium of heart
How are systemic veins categorised?
Return oxygen-depleted blood from the rest of the body to right atrium of heart
How are superficial veins categorised?
Located close to surface of the skin and are NOT located near a corresponding artery
How are deep veins categorised?
Located deep between tissues and typically located near a corresponding artery
What are the smallest veins in the body?
Venules
They receive blood from arterioles and capillaries.
What is the largest vein in the body? Where do they drain to?
The vena cava
(2 of them-superior and inferior)
Drain into right atrium of heart
What is the definition of an artery?
Arteries are elastic blood vessels that carry blood AWAY from the heart
What are the 3 layers of arteries?
Tunica intima = elastic membrane lining and smooth endothelium (non-fenestrated)
Tunica media = smooth muscle ad elastic fibres (thicker in arteries than veins and has 2 distinct elastic layers)
Tunica externa = throng other covering of collagen and elastic fibres
What are the differences between arteries and veins structures?
Arteries have much thicker walls to deal with higher BP.
Vein has very thin elastic layer (low pressure)
Why do capillaries have thin walls + narrow lumen?
To bring blood into close contact with body tissue to allow diffusion
WBC’s can diffuse between cells of the capillary wall to tissues
What are collateral blood vessels?
They provide protection for tissues that may become compromised
They provide a alternative path for arterial blood to flow.
Some are generated due to chronic disease such as ischemia
Some are produced during development
They take time to develop
What is vasculogenesis?
The formation of new blood vessel using angioblast precursors such as bone marrow.
This makes new vessels from nothing in an embryo 9forms the heart and primitive vasculature.
What us angiogenesis?
The formation of new blood vessels using existing blood vessels
Eg branching in the embryo or post-natal lung development
Uses FBGF
