Session 8 Flashcards
What are the different types of bone?
short long flat irregular sesamoid
Describe the long bones
longer than they are wide
include the femur (the longest bone in body) and small bones in the fingers
long bones are mostly located in the appendicular skeleton
function: to support the weight of the body and facilitate movement
Describe the short bones
approximately as long as they are wide
wrist and ankle joints
the carpals in the wrist (scaphoid) and the tarsals in the ankles (calcaneus)
part of the appendicular skeleton
function:
short bones provide stability and some movement
Describe the flat bones
somewhat flattened, with roughly parallel opposite edges
in the skull (occipital), thoracic cage (sternum and ribs), pelvis (ilium)
function:
protects internal organs, also provide large areas of attachment for muscles
Describe the irregular bones
vary in shape and structure and therefore do not fit into any other category
fairly complex shape
vertebrae and sacrum
function:
protect internal organs
vertebrae in the vertebral column protect the spinal chord
pelvis (sacrum) protect organs in the pelvic cavity
provide important anchor points for muscle groups
Describe the sesamoid bones
bones embedded in tendons small, round bones found in the tendons of hands, knees and feet the patella (kneecaps) is an example of a sesamoid bone (generated postnatally)
functions:
protect tendons from stress and damage from repeated wear and tear
What is cancellous and compact bone?
cancellous bone
forms a network of fine bony columns or plates to combine strength with lightness
the spaces are filled by bone marrow
compact bone
forms the external surfaces of bones and comprises approx 80% of the body’s skeletal mass
What are the types of bone marrow?
red marrow full of developing red blood cells rich blood supply only found in spongy bone function: to. replenish cells in the blood (haemopoiesis)
yellow marrow
full of adipocytes
poor blood supply
function: shock absorber and energy source, can convert to red marrow
(provides every for developing blood cells)
Describe cancellous bone
each trabeculum consists of numerous osteocytes embedded within irregular lamellae
osteoblasts and osteoclasts on their surfaces act to remodel them
How do the maturing cells leave the bone?
blood travels down the nutrient artery and up into the sinusoidal capillary bed
bone marrow cells enter the bloodstream through the sinusoidal capillaries and travel out in the blood through the central marrow vein and into t he vena comitans
Which way are other cells released?
released through sinusoids
have an incomplete basement membrane
Describe sinusoid vessels
Cells have aquaporins and glycophorins on their membranes (holds in the bone marrow)
These allow emerging cells to attach to the endothelial cells and escape
Describe the circulation, involving RBCs and WBCs
Newly formed RBCs travel from
Venule ➡️ intermediate vein ➡️ larger vein➡️ vena cava
During circulation RBCs become mature (in 2 days)
Newly formed WBCs take the same route
- T cells need the actions of the thymus to become mature and lymphatic organs (waits here to be needed)
- B cells already mature
Describe the microcirculation with capillaries
Flow in capillaries is controlled by precapillary sphincters
These PS are located between arterioles and capillaries
- contain SMC, contraction
- when open blood flows to capillary bed
- when closed no blood flows to capillary bed
Function: controls fluid exchange between the capillaries and the body tissues
Larger cells cannot pass through the capillaries and bypass the capillary bed
How are veins structured?
Vein= an elastic blood vessel that transports blood from various regions of the body to the heart Consists of three layers: Tunica intima, endothelial cells Tunica media, elastic fibres and SMC Tunic externa, elastic fibrous capsule
Non return fibroelastic cartilaginous valves assist flow towards the heart
Low pressure system so relies on muscle contraction to return blood to the heart
Vein problems occur due to either a blood clot or a vein defect behind the valves
What are the different types of veins?
Pulmonary- carry oxygenated blood from the lungs to the atrium of the heart
Systemic- return oxygen depleted blood from the rest of the body to the right atrium of the heart
Superficial- located close to the surface of the skin and are not located near a corresponding artery
Deep veins- located deep between tissues and are typically located near a corresponding artery with the same name
