IB DP Biology Muscle and motility Study Notes
IB DP Biology Muscle and motility Study Notes
IB DP Biology Muscle and motility Study Notes at IITian Academy focus on specific topic and type of questions asked in actual exam. Study Notes focus on IB Biology syllabus with guiding questions of
- How do muscles contract and cause movement?
- What are the benefits to animals of having muscle tissue?
Additional higher level: 3 hours
B3.3 Muscle and motility (HL only)
Movement as a characteristic of life (HL only)
⮚ Movement = one characteristic of living organisms
- Movement inside cells
e.g. cytoplasmic streaming
- Movement within organisms
e.g. contractions of the heart
- Movement of the whole organism = locomotion
e.g. walking, running, jumping, swimming
Use of muscles in locomotion
Three basics mechanisms for locomotion for animals
1. Amoeboid movement
e.g. Amoeba, White blood cells
2. Using cilia and flagella
3. Muscular locomotion
Organisms are:
- Sessile(can move from one place to another)
- Motile(cannot move from one place to another)
Why do organisms move?
Forging the food
Escaping from danger / Foraging for food
Finding a mate
Migration
The musculo-skeletal system (HL only)
⮚ Support system of animals = skeleton
⮚ Arthropods: skeleton is outside = exoskeleton
Vertebrates: skeleton is inside = endoskeleton
⮚ Support system of animals = skeleton
⮚ Insects: skeleton is outside = exoskeleton
Vertebrates: skeleton is inside = endoskeleton
⮚ Skeleton made of many bones + tendons + ligaments + joints
Adult human body has 206 bones
⮚ In addition to skeleton itself, movement made possible by
Skeletal muscles
Nerves
Bones
⮚ Support + partially protect body parts
⮚ Articulate with other bones at joints
⮚ Anchorage for muscles through tendons
⮚ Human skeleton
– Axial skeleton = skull + vertebral column
– Appendicular skeleton = limb girdles and limbs
Girdle = set of bones that connects a limb to the axial skeleton
Ligaments
⮚ Connect bone to bone
– Restrict movement at joints
– Prevent dislocation
⮚ Form protective capsule around movable joints
⮚ Connective tissue + fibroblasts
– Made of fibres of protein collagen
– Very slightly elastic
Tendons
⮚ Attach muscles to bones
⮚ Connective tissue + fibroblasts
– Made of fibres of protein collagen
– Slightly elastic
– More elastic than ligaments
Skeletal muscles
Three types of muscles = skeletal, smooth and cardiac muscles
⮚ Skeletal muscles:
– Cause movements by contraction
– Anchored to bones by tendons at joints
– Occur in antagonistic pairs
One muscle contracts, the second is stretched
Agonist = muscle creating flexion when contracting i.e. biceps, quadriceps
Antagonist = muscle creating extension when contracting i.e. triceps, hamstrings
Antagonistic pairs of muscles
Breathing in: volume of thoracic cage increases, pressure decreases until lower than atmospheric air’s, air moves in external intercostal muscles contract, internal intercostal muscles relax
Breathing out: volume of thoracic cage decreases, pressure increases until higher than atmospheric air’s, air moves out internal intercostal muscles contract, external intercostal muscles relax
Bones, ligaments, muscles, tendons and nerves of the hand
