Exploring the Human Skeletal System: Adaptations and Function

1. Locomotion

2. Locomotion • Locomotion: the ability to move from one place to another • Motile: capable of locomotion • Sessile: incapable of locomotion; stationary

3. Advantages of Locomotion • Increases survival (avoid predators and dangers) • Increase food opportunities • Increase ability to find mates, shelter, water etc.

4. Adaptations • Algae: some have flagella • Protozoans • Paramecium use cilia (hair-like projections) • Amoeba use pseudopods (“false feet”) • Euglena use flagella (tail-like projections) • Hydra • Mostly sessile • Contractile fibers used for somersaults

5. Adaptations • Some sessile animals use protection in large numbers • Coral reefs • Others use chemical defense • Poisons/toxins found in the stingers of jelly-fish and sea anemones

6. Human Locomotion • Involves the interaction of bones & muscles • Bones provide the structure and muscles provide the movement

7. Skeletal System • Humans have an endoskeleton • Functions of bones • Protection of internal organs • Support/shape • Anchorage for muscles • Leverage for movement • Production of blood cells (bone marrow) • Store minerals (ex. Ca2+)

8. Organization of Bones • Number of bones • Baby: approx. 350 • Adult: 206 • Skeleton has two major subdivisions: • Axial: “central core” (skull, vertebrae, ribs & breastbone) • Appendicular: “appendages”; that which attaches

9. Axial Skeleton (80 Bones) • Skeleton of the trunk & head • Skull • Cranium (8) • Frontal (1): forehead • Parietal (2): above temporal • Temporal (2): sides/temples • Occipital (1): back of the head • Sphenoid (1): temple/eye area • Ethmoid (1): part of eye socket

10. Skull cont. b) Facial (14) • Nasal (2): nose bridge • Maxillary (2): upper jaw • Zygomatic (malar) (2): cheek bones • Mandible (1): lower jaw • Lacrimal (2): eye socket (inner corner) • Palatine (2): form hard palate • Inferior conchae (2): nasal cavity • Volmer (1): nasal cavity

13. 1 in each ear Skull cont. c) Ear bones (6) • Malleus (hammer)(2) • Incus (anvil) (2) • Stapes (stirrup) (2)

14. Axial Skeleton 2) Hyoid (1): neck (non-cervical) doesn’t form a joint 3) Vertebral column (26) • Cervical (7): neck • Thoracic (12): back of chest • Lumbar (5): lower back • Sacrum (1): fused lower • Coccyx (1): fused tailbone

15. Axial Skeleton cont. 4) Sternum & ribs • Sternum (1): breastbone • True ribs (7 pairs): join w/ sternum • “false” ribs (3 pairs): join w/ last true rib (not sternum) • “floating” Ribs (2 pairs): don’t join sternum

16. Lower arm Appendicular Skeleton (126 bones) • Upper extremities (64) • Clavicle (2): collarbone • Scapula (2): shoulder blade • Humerus (2): upper arm • Radius (2) • Ulna (2) • Carpals (16): wrist • Metacarpals (10): hand • Phalanges (28): fingers

17. Mrs. Cole’s sister w/broken clavicle 

18. Appendicular Skeleton cont. 2) Lower extremities • Pelvic bone (3): • ilium, ischium & pubis • Femur (2): thigh • Patella (2): knee cap • Tibia (2): shin • Fibula (2): lower leg • Tarsals (14): ankles • Metatarsals (10): foot • Phalanges (28): toes

20. Connective Tissues(other than bone) • Cartilage: • Flexible • Elastic • Fibrous • Cushions joints • An embryo’s skeleton is mostly cartilage • As development occurs, cartilage becomes bone (ossification)

21. Connective Tissues cont. • Cartilage is found in adults: • End of ribs • Between vertebrae • End of bones (joints) • Ears, nose & trachea

22. Connective Tissue cont. • Ligaments: tough & elastic • Connect bone to bone @ joints (knee, elbow etc.) • Tendons: tough & inelastic • Attach muscle to bone

23. Joints • Place where two bones meet • 5 types: • Immovable/fixed: no movement (ex. skull and pelvis) • Hinge: back & forth motion (ex. knee & elbow) • Ball & socket: one bone fits into another; movement in all directions (ex. shoulder & hip)

24. Gliding joint Pivot joint Joints cont. • Pivot: side to side and up & down movement (ex. neck) • Gliding: allows bending and twisting (ex. wrist and vertebrae)

25. Muscles • Tissue made of cells “capable of contracting and exerting a force” • Voluntary: under conscious control (somatic NS) • Involuntary: not under conscious control (autonomic NS)

26. Cardiac muscle fiber (red) Fibrous cells (green) 3 Types of Muscle • Cardiac: • only in heart • Involuntary and cannot fatigue! • Striated/striped

27. Cross-striations Intercalated disc nucleus

28. muscle • Smooth (visceral): • Found in walls of digestive tract and blood vessels • Involuntary • Appear smooth/not striated

30. muscle • Skeletal • Found fastened to bones of skeleton • Voluntary • Striated • Function is to move bones in a coordinated manner

31. nucleus Cross-striations Muscle cell

32. Skeletal Muscles • Work in antagonistic pairs (opposite directions) • Ex. Bicep & triceps • Bicep muscle bends/flexes: called flexor • When bicep flexes, triceps relaxes (called an extensor) making it possible for arm to bend

33. Antagonistic Pair

34. Skeletal Muscle Fatigue • Under “normal” conditions, muscle cells use O2 for energy (aerobic respiration) • During vigorous activity, muscle cells can function for a short time w/ available O2 until supply cannot keep up w/ demand for O2 and cells revert to anaerobic respiration • Lactic acid builds up and causes muscle fatigue