Endocrine system Flashcards
What is the structure of the musculoskeletal system?
Made of bones, joints, cartilage, ligaments, tendons, nerves and blood vessels
What is the axial skeleton?
Skull, vertebrae and ribs
What is the appendicular skeleton?
Limbs, pelvis, scapula and calvicke
What are the 4 types of bone cells?
Osteogenic - stem cells into osteoblast
Osteoblast - forms bone tissue
Osteocyte - maintains bone tissue
Osteoclast - reabsorption and destruction of matrix
What is ossification?
Skeleton develops from embryonic mesenchyme
Cells condense
Inter-membranous ossification
Endochondral ossification
How do bones grow?
Cartilage continually grows and is replaced by bone
What are the 4 steps of bone reformation?
- Hematoma formation
- Callus formation
- Callus ossification
- Bone remodelling
What are the three main types of joint?
- Synovial
- Fibrous
- Cartilaginous
What are the 6 subtypes of synovial joint?
- Planar
- Hinge
- Pivot
- Condyloid
- Saddle
- Ball and socket
What is osteoarthritis?
Thinning cartilage causes bones to rub together
What is rheumatoid arthritis?
Swollen and inflamed synovial membrane causing bone erosion
What is the importance of calcium?
Most abundant in body
A YA has 1.1 kg of calcium in body
99% in skeleton
What are the three ways calcium distributed in plasma?
Protein bound
Complexed
Free ionised
What are the 6 functions of calcium?
Nerve function
Muscle contraction
Blood clotting
Skeletal mineralisation
Cellular metabolism
Cell signaling
What is parathyroid hormone?
produced by chief cells of parathyroid gland
single chain polypeptide MW9500
How is PTH secretion regulated?
Ca2+ acting via the calcium sensing receptor
In the long term, calciferol acts directly on the gland
What does PTH do in the kidney?
Stimulates Ca2+ reabsorption in distal
Inhibits PO43- reabsorption in proximal
What does PTH do in the bone?
Stimulates effluent of Ca2+ from exchanging pool
Increased activity of osteoclasts
What is calcitriol?
Active metabolite of vit D3
What are the actions of calcitriol?
- Stimulates absorption of Ca2+ and PO43- in GI tract
- Increases activity of osteoclasts in bone
- faciliatates Ca2+ reabsorption in kidneys
What is calcitonin?
Single chain polypeptide MW3500
Secreted by paradoxical at C cells of thyroid gland
What are the actions of calcitonin?
- Stimulates absorption of Ca2+ and PO43- in GI tract
- Increases activity of osteoclasts in bone
- faciliatates Ca2+ reabsorption in kidneys
What is hypercalcaemia?
Associated with XS parathyroid hormone
e.g. tumour of parathyroid gland
Affects bones, kidneys, GI tract as well as neurological symptoms
What is hypocalcaemia?
Lack of parathyroid hormone effect e.g. PTH resistance
Lack of vitamin D effect e.g. intake, drug interaction
Symptoms related to neuromuscular excitability
Long term lack of vitamin D affects bone growth
Examples: osteomalacia, rickets, osteoporosis
What are the three classes of hormone?
Amino acids/Amines
Peptides and proteins
Steroids
What are some examples of peptide hormones?
Short amino acid chains e.g.
ADH (9 AA)
Oxytocin (9 AA)
Polypeptides e.g.
Insulin (135 AA)
Prolactin (198 AA)
What are 3 amide hormones?
Catecholamines derived from tyrosine
adrenaline, noradrenaline
Thyroid Hormones also derived from tyrosine
thyroxine, triiodothyronine
(Indoleamines derived from tryptophan
Melatonin)
What are some examples of protein hormones?
Thyroid stimulating hormone
Follicle stimulating hormone
Growth hormone
What is endocrine communication?
Messages disseminated from glands to effector via circulation
Relatively slow transfer of information
Can be long lasting
All cells contacted, specificity conferred by receptors
What ar the 4 types of endocrine disorders?
- Hypo-secretion
e.g. type I diabetes - Hyper-secretion
e.g. pancreatic endocrine tumour - Hypo-responsive
e.g. insulin resistant type II diabetes - Hyper-responsive
e.g. hyperthyroidism
What are beta-cells?
produce and release insulin
stimulates glucose utilization and uptake
What are alpha-cells?
produce and release glucagon
increases breakdown of glycogen and glucose release