Lec 16 Exercise and Locomotion 1

Sources of ATP in muscle cells

1. Creatine phosphate

2. Glycolysis

3. Oxidative Phosphorylation

Creatine phosphate

high-energy molecule that stores phosphate for very rapid (8-10 seconds) generation of ATP

Glycolysis

Produces 2 ATP per glucose, does not require oxygen, occurs in the cytoplasm, quick generation of ATP (lasts about 90 seconds)

Oxidative phosphorylation

Produces 36 ATP per glucose, requires oxygen, occurs in mitochondria, slow generation of ATP

Muscle Fiber Types

1. Slow oxidative (red fibers)

2. Fast oxidative (intermediate fibers)

3. Fast glycolytic (white fibers)

Myoglobin

_______ is what gives the muscle fiber it’s red color (as hemoglobin does in blood)

Slow Oxidative Fibers (Red Fibers)

• These fibers are rich in myoglobin (which gives them their red color), and they rely on aerobic metabolism for energy.

• They are slow to contract but can sustain contractions for a longer period.

• These fibers are fatigue-resistant and are ideal for endurance activities, such as long-distance running.

Fast Oxidative Fibers (Intermediate Fibers)

• These fibers are intermediate between slow oxidative and fast glycolytic fibers.

• They are also involved in aerobic metabolism, but they have a faster contraction speed than slow oxidative fibers.

• They are fatigue-resistant but can generate more power and contract faster than slow oxidative fibers.

Fast Glycolytic Fibers (White Fibers)

• These fibers rely on anaerobic metabolism and have less myoglobin, which gives them a paler color.

• They contract rapidly and with high power but are prone to fatigue quickly.

• These fibers are used for short bursts of intense activity, such as sprinting or weightlifting.

speed/calcium

The ______ of tension/force generation is related to the dynamics of ______ regulation in the cell (how fast it can be pumped in and out of the cytoplasm).

ATP/decreases/sarcoplasmic reticulum

Studies suggest ____ is not usually the limiting factor for muscle fiber fatigue, but ______ in Ca2+ release from the _________ has been implicated in several studies

Velocity of shortening

How fast a muscle fiber can contract

Fast glycolytic fibers/force/power

________ fatigue more easily, but can generate more ______ and more _______ rapidly

Slow oxidative fibers/rapid/powerful

________ do not fatigue, but cannot generate ______ or very ________ contractions

velocity/myosin/ATPase

The _______ of contraction is related to the type of _______ expressed in the cell. Myosin isoforms differ in their _______ rate (the speed at which they can break down ATP)

red muscle/white muscle

In fish, there is _______ for slow, steady swimming and ________ for high-speed swimming (escape response)

Sympathetic/metabolic/proportions

When exercising, ________ nervous system activity increases. _______ rate increases (in muscle cells, liver, etc.). _______ of source of ATP changes over duration of exercise

Acetyl CoA/lipids

When we exercise for long periods of time, the source of _________ that goes into oxidative phosphorylation changes from using glucose and glycogen to using ______

3-10x/blood flow

_____ increase in _______ to skeletal muscle when exercising

small to moderate/mean arterial pressure

______ increase in ________ when exercising (93mmHg to 113mmHg ish)

vasodilation

When exercising, ________ occurs (particularly to skeletal muscle→ decreased resistance)

EDV/stroke volume/heart rate/2-6x/cardiac output

When exercising: due to ______ increasing, along with ______ (can be up to 50%), and a 2-3x increase in ________, there is a total ____ increase in ________

brain/absolute/rest

When exercising, the proportion of blood to the ____ is less, but the _______ amount of blood is slightly higher than at ______

heart/skeletal muscle/skin

During exercise, more blood is sent to the _____, _______, and ___

gut/kidney

During exercise, less blood is sent to the _____ and _____

ventilation/rate/depth/20x/alveolar

When exercising _______ increases: Breathing _____ and _____ increase (up to _____ increase in the _______ ventilation rate)

Pulmonary capillaries

When exercising, an acute changes in ventilation is the _______ dilating

cardiovascular delivery of oxygen

While ventilation and oxygen consumption increase during exercise, the ________________ becomes the limiting factor for performance, especially at higher intensities.

VO2 max

Maximal rate of oxygen consumption by the body (aerobic capacity)

cardiovascular

In athletes, VO₂ max is often higher because they have more efficient _________ systems, able to deliver oxygen more effectively to the muscles.

enzymes/oxidative phosphorylation

In response to endurance training, there’s an increased expression of ________ involved in _________

mitochondrial density/lipid droplets/fiber

In response to endurance training, there’s an increase in _________ and _________ which is consistent with switch in _____ type (more oxidative type)

activity

The proportion of people’s muscle fiber types varies by _______ level

muscles/skeleton

Movement requires ______ exerting a force on a ________ (supporting structures of body)

types of skeletons

1) Endoskeleton

2) Exoskeleton

3) Hydrostatic skeleton

Endoskeleton

a hard internal skeleton

vertebrates/cartilage/bone

Endoskeletons are typical for ________ (e.g. fish, amphibians, reptiles, birds, mammals). They can be made of ______ or ____ (primitive vertebrates, including lampreys and sharks have skeletons that are 100% cartilage)

antagonistic

In endoskeletons, muscles are arranged in ________ pairs

Examples of Antagonistic Muscles

1. Biceps and triceps.

2. Gluteus maximum and hip flexors.

3. Hamstrings and quadriceps.

4. Pectoralis major and latissimus dorsi.

5. Gastrocnemius and tibialis anterior.

6. Abductor and adductor.

Exoskeleton

a hard external skeleton

invertebrates

An exoskeleton is typical for some _________ (e.g. insects, crustaceans).

Cuticle

Hard, secreted outer layer of the exoskeleton, made primarily of chitin (a polysaccharide), along with protein and lipids.

Hypodermis

Cellular layer, secretes chitin, protein, lipids that make up cuticle

Myotendon Junction

Sites at which muscles connect to exoskeleton

Hydrostatic skeleton

Type of skeleton found in many soft-bodied animals that uses fluid-filled cavities within the body to provide support and enable movement. These cavities, under pressure, allow muscles to contract against a fluid, creating movement or maintaining shape. 

incompressible fluid/internal

In a hydrostatic skeleton, muscles move _________ through ________ compartments to achieve movement.

invertebrates

Hydrostatic skeletons are found primarily in ________ (e.g. leeches, earthworms, squids).

Cuticle/epidermis/circular muscle/longitudinal muscle

Layers of the hydrostatic skeleton from outermost to innermost

Fluid mechanics

the physics of fluids (gases and liquids, i.e. air and water)

Reynolds Number/inertial forces/viscous forces

The ______ is a dimensionless ratio that compares the relative effects of _______ (tendency of an object to keep moving) to ______ (friction from the fluid) acting on an organism moving through a fluid (like water or air).

fluid/size/shape

The Reynolds number (Re) reflects the properties of the _____ and the _____ and ______ of the animal.

VLp/u

Formula for Reynolds number

velocity of movement/linear dimension of animal/density of fluid/viscosity of fluid

Reynolds number is calculated by multiplying the _____, _____, and ______. Then dividing by the ________

sizes/environments

The Reynolds number helps explain how organisms of different _____ and ________ move efficiently

speed/momentum

At high Re, creatures rely on ______ and ______ (inertial forces have greatest influence on locomotion)

resistance/propulsion

At low Re, creatures must cope with ______ and use different ______ strategies. (viscous forces have the greatest influence on locomotion)

Velocity/flow

_______ of the fluid relative to the object affects ____ (laminar vs tubulent)

increased

A denser fluid means _______ energetic cost of movement

laminar

A slow velocity of fluid means _____ flow

turbulent

A fast velocity of fluid means _____ flow

Turbulence

_________ increases the energetic cost of locomotion

orientation

The _________ of an organism affects the formation of turbulence

Boundary layers

Regions where the fluid flow slows down due to friction between the fluid and the object's surface

same

With low viscosity there is much less friction between the fluid and the animal → the layers of the fluid will move at the _____ rate.

velocity

Boundary layers (resulting from higher viscosity / increased friction) reduce the _______ of an object and increases energetic costs of movement

higher

Larger animals have _______ Reynolds numbers than small animals

High Re

• Inertial forces dominate.

• Organisms are generally larger or moving faster.

• Momentum carries them forward.

Low Re

• Viscous forces dominate.

• Organisms are very small or moving slowly.

• Movement is heavily resisted by fluid viscosity, so inertia is negligible.

drag

streamlining reduces _____

streamlining

design or provide with a form that presents very little resistance to a flow of air or water, increasing speed and ease of movement.

Friction drag

• Drag that results from the interaction between the fluid and object.

• Occurs when the layers of fluid near the object's surface move at different speeds.

• This type of drag increases with the roughness of the surface and is reduced by making the object's surface smooth.

Pressure drag

• Force required to redirect the fluid around the object. It occurs when fluid has to change direction to flow past the object, creating a low-pressure zone behind the object.

• Streamlining the object (making it more tapered) reduces the size of the low-pressure zone, thereby reducing this type of drag

Fish/tail/swirling vortices

______ generate forward propulsion by moving ____ side to side: generates ________ that provide force for forward movement

Buoyancy

Increased ________ can decrease the cost of locomotion in water

fat/air

____ and ___ are both less dense than water

gas/bladders

_____ filled swim _______ increase buoyancy – decrease the cost of swimming

barnacle/lipid

To increase buoyancy, _______ larva have _____ droplets

fat

To increase buoyancy, aquatic mammals have ___ that also helps with insulation

Swim Bladders

gas-filled organs that help fish regulate their buoyancy in the water

Types of Swim Bladders

1. Physoclist swim bladder

2. Physostome swim bladder

Physosclist swim bladder

• This type of swim bladder can control the volume of gas in the swim bladder by moving gases between the gas gland and the oval (a part of the swim bladder).

• Gas is added through the gas gland, and gas can escape through the oval window.

Physostome swim bladder

• The gas in this type of swim bladder is controlled through a pneumatic duct that connects the swim bladder to the esophagus.

• Fish with this type can gulp air to fill their swim bladder or release gas through the same duct to deflate it.

Antagonism

There is _______ of Muscles During Bird Flight

pectoralis

For the downstroke of bird flight, the _______ muscle is important

Supracoracoideus

For the upstroke of bird flight, the _______ muscle is important

contracts/relaxes

On the downstroke, the pectoralis muscle _______, while the supracoracoideus _______, and vice versa

hover/upstroke/supracoracoideus

Hummingbirds _______ a lot so they use _______ more frequently, so larger ___________ muscle

Bernoulli’s Principle

a faster moving fluid produces less pressure than the same fluid moving at a slower speed

faster/pressure/slower/pressure/lift

The shape of the bird's wing (airfoil) creates a situation where ______ air flow on top reduces _______, while ______ air flow beneath increases _______, producing ____

Wing Loading

weight of the bird divided by the bird’s wing area

High/speeds/maneuverability

____ wing loading is efficient and advantageous for high ______, but reduces _________

types of muscle attachment for flight in insects

1. Direct muscles

2. Indirect muscles

Direct muscles

direct connection between muscles and wings

Indirect muscles

Attached to cuticle on body (flatten vs. expand entire body to move wings)

Indirect/direct

______ muscles (40-1000/sec) lead to higher wingbeat frequencies than _______ muscles (20-40/sec)

Synchronous flight muscles

• Contraction initiated by an Action Potential

• Generate one contraction for one Action Potential

• Contraction and relaxation requires a Ca2+ transient: relaxation can only happen as fast as Ca2+ can be removed from cytoplasm.

• This requires lots of ATP to run the SERCA pumps to put Ca2+ back in the sarcoplasmic reticulum.

• Found in insects with larger wings and wingbeat frequencies less than 100 beats per second like dragonflies, moths and butterflies

action potential

In both synchronous and asynchronous flight muscles, contraction is initiated by an __________

one contraction/one action potential

In synchronous flight muscles, you generate __________ for _________

Ca2+ transient/removed

In synchronous flight muscles, contraction and relaxation requires a _______: relaxation can only happen as fast as Ca2+ can be ________ from cytoplasm. This requires lots of ATP to run the SERCA pumps to put Ca2+ back in the sarcoplasmic reticulum.

larger/100

Synchronous flight muscles are found in insects with _______ wings and wingbeat frequencies less than ____ beats per second like dragonflies, moths and butterflies