Animal Lesson 8 Flashcards
Hardened support structures can be what?
external, internal, or absent
What do hardened support structures do?
Keeps the body up right
Hydrostatic skeleton
fluid held under pressure in a closed body compartment to make it feel hard against the body. E.g., worms, jellyfish, sea anemone.
Jellyfish
Not competely enclosed. With special epithelial muscular cells around they can close off opening and become really hard.
Endoskeleton
hardened internal skeleton. E.g., sponges (why they stay up right), echinoderms (made up of ossicles that are intertwined on the inside), chordates (us made up of bone and cartage).m
Exoskeleton
hardened external skeleton. Soft part attached inside of their exoskeleton to protect themselves and create movement. E.g., arthropod cuticles (insects and hardshell fish) and mollusc shells.
How do worms crawl?
Peristaltic Crawling
Long and skinny worm shape
Longitudinal muscle relaxed (extended). Circular
muscle contracted.
Short and fat worm shape
Circular muscle relaxed. Longitudinal muscle
contracted.
Steps of how warms crawl
Head is contracted then it extends forward, graple onto the bottom and then squeezing the individual segments together and bringing the back of its body back this way.
Bristles
Part of worm graple to the ground.
Main part of worm
Segments with fluid in a closed cavity through whole body.
The two muscles of the worm
An example of antagonist muscle pairing. They work in opposite direction, if both happen at same time because you won’t move.
Can animals with a hydroskeleton jump?
Yes they can. They use hydrostatic pressure.
Endoskeletons and exoskeletons generate movement using what?
muscles attached to the hard parts of a skeleton.
What are the bicep and tricep attached to in humans?
Bicep attached to the inside part of lower arm bone. Tricep attached to the other side underneath the elbow.
Antagonistic muscles
generate opposite movements across a joint. When one contracts, the other must relax.
Flexion of human arm
Biceps contract and pulls arm bone towards it while tricep is relaxed.
Extension of human arm
Tricep contracts and shortens and pulls bone from outside outwards. While the bicep is relaxed.
Bicep is a what?
Flexor
Tricep is a what?
Extensor
Grasshopper leg movement
Leg comes in when flexor muscle (that’s inside the extensor) contracts. Leg extends out when the extensor muscle contracts.
Vertebrate skeletal muscle example of hierarchical organization
Skeletal muscle composed of Muscle fibres (each a multinucleated muscle cell) composed of Myofibrils composed of Thin (actin) + thick (myosin) filaments.
Bundle of muscle fibres are kept together by what?
A membrane
A single muscle fiber (cell) is surrounded by what
plasma membrane
Myofibril
An organelle. looks like sections because of Z lines.
Sarcomere
Functional unit. They contract inwards to shorten the while length of the muscle cell.
Myofibrils are composed of what?
thin (actin) and thick (myosin) filaments.
Thin filament
Two chains of actin molecules connected at the tail end. Two of them are connected to the Z line. They move towards centre.
Myosin binds to what?
Myosin-binding sites.
Thick filament
Multiple myosin molecules with their head exposed. Many molecules together kind of forming a bundle. Their tails connected at middle (m line).
Myosin
motor protein (ATP→movement). With ATP it generates movement. It’s responsible for creating contraction.
A sarcomere is composed of what?
multiple thick and thin filaments bounded by Z lines.
M line
The connection allows for it to move.
Skeletal muscle is what?
striated muscle because they look like a bunch of lines together. The sections are darker when the two sections are overlapping each other.
Fully contracted muscle
Fully overlapped (darker under microscope).
Step one of muscle contraction
ATP is bounded to the myosin head and that’s why it’s bend (low- energy configuration). ATP is stored in bonds, so not using energy just has the potential to. When the head is bent it can’t connect to the thin filament.
Step two of muscle contraction
Hydrolysis causes ATP to release. So ADP and P is attached to myosin head. This causes a high-energy configuration and since it’s upright it can bind.
Step three of muscle contraction
The myosin head and binding-site attach together and creates a cross-bridge (the space between them).
Step four of muscle contraction
The ADP and P detach from the myosin head. This causes the thin filament moves toward center of sarcomere. This cause the myosin head to go back to low energy configuration (this is contraction).
Step five of muscle contraction
The ATP attach to head and the myosin head detaches from thin filament.
How does the muscle know when to contract?
Skeletal muscle contraction is initiated by motor neurons, these nerve impulse releases Ca+ from sarcoplasmic reticulum into the muscle fiber. Results in an increase in free Ca2+ in myofibrils of muscle
cells to allow contraction. Need ATP and Ca+. Nerve is attached to muscle cell.
How does the muscle know when to contract (thin filament)?
Ca2+ interacts with thin filament regulatory proteins (tropomyosin & troponin), exposes myosin binding site, allows myosin binding.
Tropomysosin
Long and skinny and twists around the thin filament. It covers the binding sites.
Troponin complex
On Tropomysosin abd hace the Ca+ binding sites on it. When Ca+ attach to it, it changes configuration to open up binding sites.
What would happen to a muscle if it was injected with a drug that degrades tropomyosin?
It would contract whenever there is sufficient ATP, because the binding sites would always be open.
Locomotion
Active travel from place to place. To move, an animal must expend energy to overcome gravity and friction.
The animal’s environment determines what?
Which of these forces is the dominant force opposing
locomotion.
Land and Air: Gravity
Water: Friction
Natural selection favours adaptations that reduce energy costs of locomotion
Animals look different if they live in mostly water or air because natural selection favouring certain forms and certain body pairs that requires us to use less energy to move around.
Adaptations are usually anatomical
Adaptations can also be behavioural
Adaptations are usually anatomical
E.g., fusiform body shape (tapered at one end and other, this makes gliding through water much more efficient), springy tendons (to run or jump).
Adaptations can also be behavioural
E.g., passive descent in diving mammal (use gavitity rather than flipping fins to go down).
Gravity is the dominant force opposing locomotion on land
Animals that locomote on land require powerful muscles and strong skeletal support to propel themselves and remain upright.
Maintaining balance is essential
When walking, bipedal (2 legs) animals keep one leg
on the ground; multi-legged animals keep three legs on the ground. When running or hopping, all legs can leave the ground; momentum keeps the body upright.
Adaptations can reduce energy expenditure
When tendons stretch as the animal lands, they store energy in elastic fibres to allow the bounce to happen to the next jump. The energy (potential energy) is released to aid the next jump.
Gravity is the dominant force opposing locomotion in air
Wings of flying animals must generate enough
lift to overcome gravity’s downward force done by the shape of the wing. Has to go faster at the top because their is more length to cover. There is more pressure going up on bottom, it’s exerted by slower moving air. This creates lift.
How do flight birds stay in air?
Flying animals tend to have low body mass
– E.g., Birds
* No urinary bladder (birds don’t pee!) (no water to drag them down).
* No teeth
* Hollow air-filled regions in bones (strong but hollow because of made of latticework of supports).
A fusiform body helps reduce drag (AKA friction).
Friction is the dominant force opposing locomotion in water
Most aquatic animals are reasonably buoyant (naturally float in water);
i.e., overcoming gravity requires little energy
But water is a denser and more viscous medium
than air; drag (AKA friction) is a problem
Fusiform body is an adaptation to reduce drag
Skeletons and muscles work together to generate what?
movement
Ca2+ interacts with regulatory proteins to what?
control skeletal muscle contraction
