BIOH111. o Cell Module o Tissue Module o Integumentary system o Skeletal system o Muscle system o Nervous system o Endocrine system

Transcription

1 BIOH111 o Cell Module o Tissue Module o Integumentary system o Skeletal system o Muscle system o Nervous system o Endocrine system Endeavour College of Natural Health endeavour.edu.au 1

2 TEXTBOOK AND REQUIRED/RECOMMENDED READINGS o Principles of anatomy and physiology. Tortora et al; 14 th edition: Chapter 6 Endeavour College of Natural Health endeavour.edu.au 2

3 BIOH111 SKELETAL SYSTEM MODULE o Session 9 (Lectures 13 and 14) Bone physiology: Building of bone organ cells, tissue, organ and repair o Session 10 (Lectures 15 and 16) - The Skeletal System: Axial and Appendicular Skeleton, Joints and Movement Endeavour College of Natural Health endeavour.edu.au 3

4 PREPARATION FOR THIS SESSION o NO MISSING CONCEPTS OR LINKING WORDS from Session 6 o Review: receptors homeostasis tissue types o Think about cells as immature and specialised (mature) why is there a difference? Endeavour College of Natural Health endeavour.edu.au 4

5 BIOH111 Lectures 13 and 14 Bone physiology: Building of bone organ cells, tissue, organ, development and repair Department of Bioscience endeavour.edu.au

6 Lecture 13: OBJECTIVES Identify and describe function of the overall skeletal system Bone cells and tissue Name and describe bone cells and their function in building and function of bone tissue Describe structure and function of 2 bone tissue types compact and spongy Long bone as an example of bone organ Describe structure and function of long bone sections Lecture 14: Development and growth of bone tissue Recognise 2 types of bone development (ossification) Describe process of growth (length and thickness) Identify steps in bone remodelling and fracture repair Endeavour College of Natural Health endeavour.edu.au 6

7 SKELETAL SYSTEM FUNCTION 1. Support structural framework for the body 2. Protection protects internal organs from injury 3. Assistance in movement muscles involved in movement attached to the skeleton 4. Mineral homeostasis major calcium and phosphorus reservoir 5. Blood cell production stem cells for production of WBCs and RBCs (red bone marrow) 6. Triglyceride storage adipose tissue; energy reserve Endeavour College of Natural Health endeavour.edu.au 7

8 BONE STRUCTURE o Bone is made up of several different tissues: bone, cartilage, dense connective tissue, epithelium, various blood forming tissues, adipose tissue and nervous tissue o 1 bone = 1 organ o bones + cartilage +ligaments + tendons = skeletal system o Bone constantly undergoes remodeling o NOTE: bone means both the tissue and the structural unit of a skeleton Building bones: cells tissue organ Endeavour College of Natural Health endeavour.edu.au 8

9 cells tissue organ BONE CELLS o Osteogenic cells undifferentiated, stem cells can divide to replace themselves & can become osteoblasts found in inner layer of bones o Osteoblasts - form matrix & collagen fibers but can t divide o Osteocytes - mature cells that no longer secrete matrix and are the principle cells of bone matrix o Osteoclasts - huge cells from fused monocytes (WBC) function in bone resorption Endeavour College of Natural Health endeavour.edu.au 9

10 CELLS OF BONE Osteoblasts Osteocytes Osteoclasts Endeavour College of Natural Health endeavour.edu.au 10

11 cells tissue organ BONE (OSSEOUS) TISSUE revision o Type of connective tissue as seen by widely spaced bone cells separated by matrix. Matrix - 25% water, 25% collagen fibers & 50% crystallized mineral salts (hydroxyapatite and some calcium carbonate) o Calcification or mineralization process of mineral salts deposition in a framework of collagen fibers Mineral salts confer hardness on bone while collagen fibers give bone its great tensile strength o Bone is not completely solid - small spaces for vessels and red bone marrow o 2 types: compact and spongy bone Endeavour College of Natural Health endeavour.edu.au 11

12 COMPACT BONE Structure: solid, hard layer of bone; makes up the shaft of long bones and the external layer of all bones Function: resists stresses produced by weight and movement Endeavour College of Natural Health endeavour.edu.au 12

13 COMPACT BONE HISTOLOGY o Arranged in units called osteons or Haversian systems. Osteons contain blood vessels, lymphatic vessels, nerves, osteocytes and calcified matrix o Osteons are aligned in the same direction along lines of stress. Endeavour College of Natural Health endeavour.edu.au 13

14 SPONGY BONE Structure: light of bone; found only on the interior of the bones; most of the structure of short, flat, and irregular bones (e.g. ribs), and the ends of the long bones Function: supports and protects the red bone marrow Endeavour College of Natural Health endeavour.edu.au 14

15 SPONGY BONE HISTOLOGY o Arranged in trabeculae (latticework of thin plates of bone) that surround many red marrow filled spaces o Trabeculae are irregularly arranged. Endeavour College of Natural Health endeavour.edu.au 15

16 cells tissue organ o 5 basic types of bones classified by shape: Long - compact TYPES OF BONES Short - spongy except surface Flat - plates of compact enclosing spongy Irregular - variable Sesamoid - develop in tendons or ligaments (patella) o Sutural bones classified by location; in sutures (joints) between skull bones Endeavour College of Natural Health endeavour.edu.au 16

17 cells tissue organ o Diaphysis: growing between ; shaft long cylindrical main portion of the bone o Epiphyses: growing over ; ends of the bone; distal or proximal o Metaphyses: LONG BONE STRUCTURE Why the bold letters? joins diaphysis and epiphyses; epiphyseal plate (<20yo; cartilage) epiphyseal line (>20yo; bone) Endeavour College of Natural Health endeavour.edu.au 17

18 o Articular cartilage: hyaline cartilage covering the part of epiphysis where the bone forms a joint; reduces friction o Medullary cavity: marrow cavity within the diaphysis; contains bone marrow o Endosteum: membrane that lines the medullary cavity; single layer of bone forming cells and connective tissue o Periosteum: tough sheath of dense irregular connective tissue that surrounds the bone surface o Nutrient foramen: entry point for blood vessels Endeavour College of Natural Health endeavour.edu.au 18

19 For interest only o Periosteal arteries supply periosteum BLOOD SUPPLY OF BONE o Nutrient arteries enter through nutrient foramen supplies compact bone of diaphysis & red marrow o Metaphyseal & epiphyseal arteries supply red marrow & bone tissue of epiphyses Endeavour College of Natural Health endeavour.edu.au 19

20 REVISION LONG BONE Structure Function Diaphysis Epiphyses Metaphyses Articular cartilage Medullary cavity Endosteum Periosteum Endeavour College of Natural Health endeavour.edu.au 20

21 Lecture 13: Bone cells and tissue OBJECTIVES Name and describe bone cells and their function in building and function of bone tissue Describe structure and function of 2 bone tissue types compact and spongy Long bone as an example of bone organ Describe structure and function of long bone sections Lecture 14: Development and growth of bone tissue Recognise 2 types of bone development (ossification) Describe process of growth (length and thickness) Identify steps in bone remodelling and fracture repair Endeavour College of Natural Health endeavour.edu.au 21

22 BONE FORMATION AND GROWTH Bone formation is termed osteogenesis or ossification and occurs in 4 situations: fetal bone formation, childhood bone growth, bone remodeling and fracture repair. o Two types of ossification occur: 1. Intramembranous ossification bone forms directly from or within fibrous connective tissue. 2. Endochondral ossification bone forms from hyaline cartilage. o Two types of bone growth occur: 1. Growth in length 2. Growth in thickness Endeavour College of Natural Health endeavour.edu.au 22

23 GROWTH IN LENGTH At birth only Articular cartilage and Epiphyseal plate have not been converted to bone sites of the bone growth in length. Endeavour College of Natural Health endeavour.edu.au 23

24 o Growth stages: GROWTH IN LENGTH e.g. EPIPHYSEAL PLATE cartilage cells are produced by mitosis on Epiphysis side of the plate cartilage cells are destroyed and replaced by bone on Diaphyseal side of the plate o Ages 18 to 25, Epiphyseal plates close. cartilage cells stop dividing and bone replaces the cartilage (Epiphyseal line) Endeavour College of Natural Health endeavour.edu.au 24

25 GROWTH IN LENGTH e.g. EPIPHYSEAL PLATE End result: extension of bone length Endeavour College of Natural Health endeavour.edu.au 25

26 GROWTH IN THICKNESS e.g. PERIOSTEUM OF LONG BONE Bone can grow in thickness or diameter only by appositional growth. Endeavour College of Natural Health endeavour.edu.au 26

27 Endeavour College of Natural Health endeavour.edu.au 27

28 BONE REMODELING Remodeling is the ongoing replacement of old bone tissue by new bone tissue. 2 stages: 1. Bone deposition construction of new bone by osteoblasts 2. Bone resorption destruction of old bone by osteoclasts; osteoclasts form leak-proof seal around cell edges and secrete enzymes (digest collagen) and acids (dissolve minerals) beneath themselves and release calcium and phosphorus into interstitial fluid through process of endocytosis and exocytosis Why is bone remodelling important? Endeavour College of Natural Health endeavour.edu.au 28

29 FRACTURE AND REPAIR OF BONE o A fracture is any break in a bone structure. o Healing is faster in bone than in cartilage due to lack of blood vessels in cartilage. o Healing of bone is still slow process due to vessel damage. o Clinical treatment: closed or open reduction. Endeavour College of Natural Health endeavour.edu.au 29

30 REPAIR OF BONE FRACTURE Step 1: Formation of fracture haematoma damaged blood vessels produce clot in 6-8 hours, bone cells die inflammation brings in phagocytic cells for clean-up duty new capillaries grow into damaged area Also see BIOS222 Endeavour College of Natural Health endeavour.edu.au 30

31 REPAIR OF BONE FRACTURE Step 2: Formation of fibrocartilaginous callus formation fibroblasts invade the procallus & lay down collagen fibers chondroblasts produce fibrocartilage to span the broken ends of the bone Endeavour College of Natural Health endeavour.edu.au 31

32 REPAIR OF BONE FRACTURE Step 3: Formation of bony callus osteoblasts secrete spongy bone that joins 2 broken ends of bone lasts 3-4 months Step 4: Bone remodeling compact bone replaces the spongy bone in the bony callus surface is remodeled back to normal shape Endeavour College of Natural Health endeavour.edu.au 32

33 REGULATION OF BONE PHYSIOLOGY o Endocrine regulation parathyroid hormone levels regulate release of Ca 2+ from stores (skeleton) into the blood supply to be used by other systems (e.g. Ca 2+ regulates nerve and muscle function and blood clothing) details of this regulation see BIOH111, session 24 o Exercise (mechanical stress) - within limits bone has the ability to alter its strength in response to mechanical stress by increasing deposition of mineral salts and production of collagen fibers, making the bones stronger Endeavour College of Natural Health endeavour.edu.au 33

34 REGULATION OF CALCIUM BLOOD Linking point to BIOH111, Session 24 LEVELS o Parathyroid hormone (PTH) is secreted if Ca +2 levels falls PTH gene is turned on & more PTH is secreted from PT gland osteoclast activity increased, kidney retains Ca +2 and produces calcitriol o Calcitonin hormone is secreted from parafollicular cells in thyroid if Ca +2 blood levels get too high inhibits osteoclast activity increases bone formation by osteoblasts Endeavour College of Natural Health endeavour.edu.au 34

35 Recap of Session 9 Bones contain several different cell types that are responsible for some of the overall functions of the skeletal system Long bone contains parts that ensure some of the functions of the overall skeletal system Bones can grow in length and width Bones are able to heal a fracture through a series of steps A specific bone cell is important in regulation of calcium levels in the blood as it is regulated by hormones Endeavour College of Natural Health endeavour.edu.au 35

36 PREPARATION FOR NEXT SESSION o Complete missing concepts and linking words from Session 9 o Review overall functions of the skeletal system o Write down any bone names you know (you will learn latin names for these in the next session) Endeavour College of Natural Health endeavour.edu.au 36

37 Revision videos Regulation of osteoclast activity-cell signalling via RANK Endeavour College of Natural Health endeavour.edu.au 37