Lecture 21 - Animal Movement 2 Flashcards
Smooth muscle cells characteristics
unstriated, have no sarcomeres, single nucleus, unbranced, contraction is involuntary and controlled by autonomic motor neurons
Where are smooth muscle cells located?
Lungs, blood vessels, digestive system, urinary bladder, reproductive system
What is the function of acetylcholine in smooth muscles?
It stimulates the contraction of muscles in the stomach and intestine
What is the function of epinephrine in smooth muscles?
It inhibits muscle contractions in the gut
Cardiac muscle cells characteristics
Striated, contain sarcomeres, 1-2 nuclei, branched, contraction is involuntary with spontaneous depolarization, contain intercalated discs
Function of intercalated discs
They form cytoplasmic connections between muscle cells, which allow electricity to flow between cells and coordinate the heart beat
What is the function of acetylcholine in cardiac muscles?
Slow the heart rate
What is the function of norepinephrine and epinephrine in cardiac muscles?
They speed up the heart rate
Parasympathetic autonomic motor neurons
Release acetylcholine to both cardiac and smooth muscles
Sympathetic autonomic motor neurons
Release norepinephrine and epinephrine to both cardiac and smooth muscles
What do both sympathetic and parasympathetic autonomic motor neurons control?
Involuntary muscle contractions
Skeletal muscle cells characteristics
Striated, thousands of sarcomeres, multinucleate, unbranched, activity is voluntary: requires signal from motor neuron
How do skeletal muscle cells form?
By the fusion of embryonic cells
Composition and location of skeletal muscle
40 to 45 percent of human body mass is skeletal muscle, skeletal muscle is attached to the skeleton
Types of skeletal muscle
Fast muscle fibers, slow muscle fibers, intermediate muscle fibers. All types are found in all skeletal muscles but in different proportions
Slow muscle fibers characteristics
Contract for a long time, fatigue very slowly, generate little force, red in color due to high myoglobin concentration, derive ATP via aerobic respiration, 30-32 ATP/glucose molecules, have many mitochondria
Fast muscle fibers characteristics
Contact very rapidly, fatigue rapidly, generate lots of force, low myoglobin concentration, appear white, derive ATP via glycolysis, 3-5 ATP/glucose molecules
Intermediate muscle fibers characteristics
Contract at a rate between slow and fast muscle fibers, fatigue at an intermediate rate, generate an intermediate amount of force, intermediate myoglobin levels, appear red or pink, derive ATP via aerobic respiration and glycolysis
Sartorious muscle characteristics
Muscles of the thigh, small cross section (thickness) which leads to small amount of force, fibers are long which lead to a large change in length
Gastrocnemius muscle characteristics
Muscles of the calves, large cross section (thickness) which leads to large amount of force, fibers are short which lead to a small change in length
Skeletal systems function
Protection, maintenance of body posture, re-extension of shortened muscles, transfer of muscle forces to other parts of the body
Types of skeletal systems
hydrostatic skeleton, endoskeleton, exoskeleton. Most animals have one or more of these skeletal systems
Hydrostatic skeletons characteristics
When fluid is under compression, its pressure increases. Pressurized internal fluids can act as a skeleton. Example: hydrostatic skeleton of an earthworm
Vertebrate endoskeleton
comprised of bones, cartilage, and ligaments. Bones articulate at the joints
