Skeletal System

1
Skeletal System

• Cells responsible for bone remodeling are?
• Where are these cell types derived from?
• Joint Types 1) Fibrous
• 2) Cartilaginous
• 3) Synovial
• Synovial Joint Examples
• 1st two vertebrae (neck) hip
• elbow base of fingers
• base of thumb ankle

2
Cell Communication

• Cells communicate using soluble signals that are
  most often secreted proteins
• Cells have specific receptors that allow them to
  convert the soluble signal into an intracellular
  response
• Intracellular response usually involves the up-
  or down-regulation of certain metabolic pathways,
  but altering DNA synthesis of other proteins

3
White Blood Cells

• LEUKOCYTES found in circulation but migrate to
  tissues to perform various functions.
• Classified as GRANULOCYTES and AGRANULOCYTES.
• GRANULOCYTES are the NEUTROPHILS, EOSINOPHILS and
  BASOPHILS
• NEUTROPHILS phagocytize foreign cells, toxins,
  viruses
• Granules contain digestive enzymes that destroys
  foreign bodies
• AGRANULOCYTES are the LYMPHOCYTES and MONOCYTES
• LYMPHOCYTES return to blood stream after
  migrating to tissue
• MONOCYTES are the largest leukocytes, they leave
  the blood stream and become MACROPHAGES
  (diapedesis)

4
Host Defence

• In order for a pathogen to enter the body, it
  must overcome the EPITHELIUM, the INNATE IMMUNE
  RESPONSE and the ADAPTIVE IMMUNE RESPONSE.
• EPITHELIAL TISSUE covers the whole body, tightly
  packed cells, interior epithelium covered in
  mucus to pathogens from adhering
• INNATE IMMUNE RESPONSE macrophages and dendritic
  cells will recognize, ingest and destroy
  pathogens (phagocytosis).
• COMPLEMENT SYSTEM consists of blood proteins
  made by the liver that 1) coat pathogens (to
  trigger immune response) and 2) disrupt pathogen
  membranes to destroy them.
• ADAPTIVE IMMUNE RESPONSE elicited by antigens in
  the body and carried out by lymphocytes B cells
  and T cells

5
Lymphocytes

• T CELLS (leave bone marrow to mature in Thymus)
• CYTOTOXIC T CELLS act locally to kill infected
  cells
• HELPER T CELLS help activate macrophages, B cells
  and cytotoxic T cells
• B CELLS (produced and mature in the Bone marrow)
  
• secrete antibodies that circulate in the body and
  coat microbes, targeting them for phagocytosis.
• As part of the adaptive immune response, some
  lymphocytes differentiate into memory cells,
  which respond faster the 2nd time they encounter
  the same pathogen.
• B and T cells circulate between the blood and the
  lymph

6
Antigen Presenting Cells

• Dendritic cells and macrophages digest invading
  cell and present the microbial antigen to
  lymphocytes

Antibodies

• Proteins that circulate in the blood defend
  against infection by
• Inactivating viruses and microbial toxins
• Recruiting WBCs to kill invading pathogens