b3.3 (muscle and motility) Flashcards
an organism that uses its own energy to move from place to place is motile. motile organisms: x4
are active feeders, searching for food
require higher amounts of nutrients
have higher metabolic rates
must search for mating partners
an organism that can not direct its movement from place to place is sessile. sessile organisms: x3
are autotrophs or passive feeders
require fewer nutrients
have slower metabolic rates
adaptations of marine mammals for swimming x5
streamlined body shape: long, narrow, tapered bodies reduce drag.
smooth skin (no body hair): minimizes friction with water.
forelimbs: modified into flippers for propulsion and steering.
tail (flukes): used for powerful up-and-down thrust.
pectoral fins: help with steering and balance.
how does blubber serve as an adaptation in marine mammals? x3
insulates
provides buoyancy
stores energy for long migrations or deep dives
how do specialized breathing techniques serve as an adaptation in marine mammals? x4
high myoglobin for oxygen storage
much more hemoglobin
control of breath and dive reflex for deep dives
blowhole that can be sealed to prevent water entry
watch a video on how dolphins echolocate
-
look at slide 19 b3.3
-
what is an exoskeleton made of?
chitin
what is an endoskeleton made of? x2
bone and cartilage
skeletons can be compared to what? what does each aspect of this structure correlate to the parts of the skeleton
a lever
lever = the skeleton
fulcrum = a joint
effort = the muscles that pull on the bone at the insertion point
load = the mass being moved (usually body’s mass)
first class lever structure & example in the body
fulcrum placed between the load and the effort (i.e. seesaw)
contractions of the muscle in the neck pull on the skull, causing the atlanto-occipital joint to pivot. the face rises.
second class lever structure & example in the body
load between the effort and the fulcrum (i.e. wheelbarrow)
contractions of the calf muscle in the leg pull on the heel, causing the metatarsophalangeal joint to pivot. the foot rises.
third class lever structure & example in the body
effort placed between the load and the fulcrum (i.e. hammer)
contractions of the bicep muscle in the arm pull on the radius, causing the elbow joint to pivot. the hand rises.
define joint
the site of the junction of two or more bones of the body
3 classifications of joints
immovable, fibrous
slightly movable, cartilaginous
freely movable, synovial
synovial joints defining characteristic
a fluid-filled space between smooth cartilage pads at the end of articulating bones
parts of synovial joints x7
joint capsule
bones
cartilage
synovial fluid
ligaments
muscles
tendons
define joint capsule
a flexible, fibrous tissue that surrounds a joint and provides protection and stability
what does cartilage in a joint do?
covers the bone at the joint to prevent friction and absorb shock
example types of synovial joints, structure, range of motion, & examples x2
hinge joints (convex surface fitting into a concave surface) (limited range of motion) (elbow, knee, finger)
ball & socket joints (rounded “ball” fitting into a cup-like “socket”) (wide range of motion) (hip, shoulder)
the hip joint is a ball-and-socket joint that connects X to X
the femur to the pelvis
how to measure range of motion x2
goniometer (a tool with two arms that are hinged together and positioned at a joint to measure the angle)
analysis of images (using computer programs or phone applications that measure angles)
directions of movement with definitions (& how they can be seen in relation to the hip) x6
flexion: bending a joint, decreasing the angle of the bones at these joints (brings leg up towards the chest)
extension: straightening a joint, increasing the angle between the bones at these joints (brings the leg backwards)
abduction: movement of a limb away from the center of your body (brings the leg outwards)
adduction: movement of a limb towards the center of the body (brings the leg inwards)
medial rotation: rotating limb toward the center of the body (brings the leg inwards)
lateral rotation: rotating a limb away from the center of the body (brings the leg outwards)
define antagonist muscle pairs
muscle pairs that work together to facilitate motion through controlling “opposite” movements (when one contracts, the other relaxes)
examples of antagonist muscle pairs x3
bicep & tricep
glute & hip flexor
quad & hamstring
antagonist muscle pairs involved in running (mid stance vs toe off)
mid stance: contracting glute to pull foot up, relaxing hip flexor (for extension)
toe off: relaxing glute to enable hip flexion. contracting hip flexor to drive knee up.
what do the external and internal intercostal muscles each do for breathing?
external intercostal muscles: (located on the outside of the rib cage) responsible for elevating the ribs during inhalation, which increases the volume of the thoracic cavity and allows air to enter the lungs
internal intercostal muscles: (located on the inside of the rib cage) responsible for depressing the ribs during exhalation, which decreases the volume of the thoracic cavity and helps push air out of the lungs
motor neurons branch at the end of the axon. what does each branch do?
stimulates a different muscle fibre
when do skeletal muscles contract?
when stimulated by a motor neuron
define motor unit
the single motor neuron together with all of the muscle fibres it stimulates
define neuromuscular junction
the synapse between a motor neuron and a muscle
when an action potential reaches the synaptic terminal of the motor neuron, it causes the release of what? how does this cause a muscle contraction?
the neurotransmitter acetylcholine into the synaptic cleft
acetylcholine triggers the opening of ion channels. Na+ ions flow into the muscle fibre and cause it to contract
what is sarcolemma
cell membrane specific to muscle cells
each myofibril consists of a series of repeated sarcomeres linked end to end (see slides 48 & 50). the sarcomeres are what give muscles their striated appearance.
what is the structure of a sarcomere x5 components
Z lines
actin (thin filament) (may also be proteins tropomyosin or troponin)
myosin (thick filament)
M line (in middle)
titin (elastic filament)
what are z-lines? what do they do?
protein structures that anchor the actin filaments and define the boundaries of the sarcomere
what is titin? what do they do?
spring like protein that anchors myosin to the Z-line and recoils the sarcomere after contraction
when a muscle contracts, the sarcomeres get shorter. how is this performed?
thin filaments (actin) are pulled inwards to slide over the thick filaments (myosin)
when the thin filament moves, the Z-lines of the sarcomere are pulled closer together, shortening the sarcomere and contracting the muscle
steps of sliding filament theory x10
(after, look at 53 to 62 for step details)
Muscle at rest
Arrival of action potential triggers release of achetolychine at the neuromuscular junction
Action potential travels along the sarcolemma membrane and down T-tubules
Release of Ca2+ ions from the sarcoplasmic reticulum
Ca2+ binds to troponin, causing tropomyosin to move off of myosin binding sites on actin
Myosin heads bind to actin, forming a crossbridge
Myosin head flexes, moving the actin filaments inwards, shortening the sarcomere
ATP attaches to the myosin heads, breaking the crossbridge
Steps 6-8 repeat in a cross-bridge cycle
Contraction ends when Ca2+ is pumped back into the sarcoplasmic reticulum
titin’s role in muscle relaxation
provides passive elasticity that helps muscles return to their resting length during relaxation
antagonistic muscle role in muscle relaxation
skeletal muscles work in pairs where one muscle contracts to produce a movement, while the other relaxes to allow that movement to occur. when on muscle contracts, the antagonistic muscle will relax
3 primary functions of titin
provides sarcomere stability by anchoring the myosin filament to the Z-line
helps sarcomeres recoil after contraction
when stretched, titin generates power for rapid motion when it recoils
define elastic potential energy. where is it typically stored in muscle cells?
the energy stored in a spring when it is stretched or compressed
stored in protein titin
why are antagonistic muscle pairs necessary?
skeletal muscles can only exert force on the bone when they contract. a muscle cannot supply the energy it needs to lengthen itself
(the energy for lengthening of a muscle is provided by the contraction of the antagonistic muscle)
