Bone, Bone Marrow, Vessels and Blood Flashcards
5 classes of bones
Long
Short
Flat
Irregular
Sesamoid
Structure and function of long bones with 2 examples
Longer than they are wide
Support weight of body and facilitate movement
Femur and small bones in fingers
Structure and function of short bones with 2 examples
Long as they are wide
Provide stability and some movement
Carpals in wrist and tarsels in ankles
Structure and function of flat bones
Flattened with roughly parallel opposite edges
Protect internal organs and provide large areas of attachment for muscles
4 examples of flat bones
Skull
Thoracic cage (sternum and ribs)
Pelvis - ilium
Scapula
Structure and function of irregular bones
Vary in shape and function with often a complex shape
Protect internal organs and provide anchor points for muscle groups
2 examples of irregular bones
Vertebrae in vertebral column
Pelvis - sacrum
What are sesamoid bones and their function? Give an example
Bones embedded in tendons
Protect tendons from stress and damage from repeated ‘wear and tear’
Patella (postnatally formed)
What is red marrow full of and where is it found?
Haemopoietic stem cells and a rich blood supply
Only found in cancellous bone
Function of red marrow
Haemopoiesis -replenish red blood cells
What is yellow marrow full of? State its function
Full of white fat cells (adipocytes) with a poor blood supply
Shock absorber and energy source
What special attribute does yellow bone marrow have when RBC counts are low? E.g anaemia
Yellow marrow has the ability to convert to red marrow for haemopoiesis
When will reticulocytes appear in the blood?
After large blood loss or anaemia
Try to balance out the lack of RBC
What hormone stimulates platelets?
Thrombopoetin
How is blood supplied to bone?
- Enters through nutrient artery
- To central vein
- Into arterioles
- Some arterioles go to the sinusoid or to periosteum
How is cortical bones supplied with blood?
Arterioles branch off from central artery where they go to the periosteum and join with haversion system and to the cortical bone
How do cell made in bone marrow leave the bone? (3)
Released into sinusoidal capillaries
Travel to the central marrow vein
And out into circulation through the vena comitans
What non-hormonal change stimulates the formation of a megakaryocyte? Why?
mechanical stiffness and marrow viscosity due to drop in blood pressure.
Loss of blood = loss of water so water diffuses into the sinusoids from bone marrow
Explain how platelets are formed and how they leave the bone
- Change in extracellular bone marrow matrix stimulates formation
- Haemopoeitic stem cells and haemopoeitic progenitor cells come together
- 2 progenitor cells fuse and divide to make a cell with 4 nuclei - 92 chromosomes (developing megakaryocyte)
- Fat cells joins developing megakaryocyte to develop it
- Too large to go through fenestrations so projects cytoplasm into sinusoids and releases cells through apopcrine secretion
Through what type of secretion are platelets released from megakaryocyte
Apocrine
Where do newly formed RBC go upon entering circulation from vena comitans?
Venule -> intermediate vein -> larger vein -> vena cava
During this time, they become mature - 2 days
Where do newly formed WBC go upon entering circulation from vena comitans?
Venule -> intermediate vein -> larger vein -> vena cava
Immature T cells need to be activated by thymus and lymphatic
B cells already mature
What is the flow in capillaries controlled by?
Precapillary sphincters
What are precapillary sphincters? Where are they located
Band of smooth muscle that can adjust to control the flow of blood in capillaries
Between arterioles and capillaries
