• Basic unit of all living things

• Example: Cardiac cells

• A group of similar cells that perform similar functions

Ex. Cardiac muscle• 4 Main Types of Tissue: 1. Muscle 2.

Epithelial (skin) 3. Nerve 4. Connective

• A group of tissues that work together to perform a specific functionex. The Heart

• A group of organs that work together to perform a certain function ex. Circulatory system

MUSCULAR SYSTEM

MUSCULAR SYSTEM• The job of the

muscular system is to move the skeletal system, help to circulate blood and move food through the digestive system.

THREE TYPES OF MUSCLES:

• 1. Skeletal: Attached to bone; at work every time we lift a finger, wink, chew and run; appears STRIATED (looks striped under the microscope); Voluntary (you have control over it)

THREE TYPES OF MUSCLES:

• 2. Smooth: Involuntary; contract without us thinking about it; not striated; found in Internal organs (stomach, blood vessels, intestines)

THREE TYPES OF MUSCLES:

• 3. Cardiac: Only found in the heart; striated (like skeletal muscle); Involuntary (don’t think about it – like smooth muscle)

Muscle Contraction

• A muscle contracts when the thin filaments in the muscle fiber slide over the thick filaments.

Control of Muscle Contraction

• Remember that motor neurons connect the central nervous system to skeletal muscle cells

• Impulses from motor neurons control the contraction of skeletal muscle fibers

• Neuromuscular Junction – the point of contact between a motor neuron and a skeletal muscle cell

How Skeletal Muscles Work

• Skeletal muscles generate force and produce movement by contracting or pulling on body parts

• Individual muscles can only pull in one direction

• Most skeletal muscles work in opposing pairs – when one muscle contracts, the other relaxes

How Skeletal Muscles Work

Mitochondria in Muscle Cells

• There are more mitochondria present in muscle cells than other types of cells because muscle cells require more energy and remember mitochondria are the powerhouse of the cell

• Also, certain types of muscles (biceps & triceps) have more mitochondria than muscles used on a less regular basis

Work• Work is the energy transfer by force

– When you push or pull on an object and it moves, you have done work on the object

• We can calculate work with the following formula– Work = Force x distance

• Units:• Work – Joules (J) = Nm• Force – Newtons (N)• Distance – Meters (m)

Work

• The whole point of your muscular system is to do work both in your body by moving it and outside your body by moving other objects

Work Example ProblemWork = Force x distance1. How much work is done when a 5 N force

moves a block 4 m?• Work = 5 N x 4 m• Work = 20 Nm or 20 J2. Fred applies 350 N force to move his stalled

car 10 m, how much work did Fred do?• Work = 350 N x 10 m• Work = 3500 Nm or 3500 J

Power• Power is the rate that work is done• You could move a pile of rocks fast or you could

move them slowly – the same amount of work will be done, but the power is different

• The faster you move the rocks the more power you have exerted

• Power = work/time• Units:

– Power – Watts (W) = J/s– Work – Joules (J)– Time – Seconds (s)

Power• You can walk a mile or run a mile and you will exert

the same amount of work (energy) – meaning you lose the same number of calories whether you walk or run a mile!)

• However, the power output is higher when you run the mile rather than walk the mile (the work was more concentrated when you ran than when you walked)– Ex. Concentrated orange juice: you could eat the can of

orange juice concentrate in one sitting or you could dilute it and drink it over time; in both cases you consumed the same amount of oranges, just at different rates

Power Example ProblemsPower = work/time1. How much power does it take to do 50 J of work in

10 sec?• Power = 50 J / 10 sec• Power = 5 J/s or 5 W2. How much power does it take to lift 30 N 10 m high

in 5 sec?• First, figure out work (W = Fxd)• W=30N x 10m or W= 300 Nm or Joules• Then, Power = 300 J / 5 sec or 60 J/s or 60 W

Newton’s 3 Laws• Your muscles must obey Newton’s 3 laws, as

do all things• Newton’s 1st Law: an object at rest will stay at

rest and an object in motion will stay in motion unless acted upon by an outside force

• Newton’s 2nd Law: the force exerted on an object can be calculated using the formula, F=ma

• Newton’s 3rd Law: for every force, there is an equal and opposite force