Unit 3 - Nervous Function & Movement
Table of Contents
Chapter 13 – The Nervous System
13.1 – Overview of the Nervous System
13.2 – The Central Nervous System
13.3 – The Limbic System and Higher Mental Functions
13.4 – The Peripheral Nervous System
13.5 – Drug Abuse
Chapter 14 – Senses
14.1 – Sensory Receptors and Sensations
14.2 – Proprioceptors and Cutaneous Receptors
14.3 – Senses of Taste and Smell
14.4 – Sense of Vision
14.5 – Sense of Hearing
14.6 – Sense of Equilibrium
Chapter 11 – The Skeletal System
11.1 – Overview of the Skeletal System
11.2 – Bone Growth, Remodeling and Repair
11.3 – Bones of the Axial Skeleton
11.4 – Bones of the Appendicular Skeleton
11.5 - Articulations
Chapter 12 – The Muscular System
12.1 – Overview of the Muscular System
12.2 – Skeletal Muscle Fiber Contraction
12.3 – Whole Muscle Contraction
12.4 – Muscular Disorders
12.5 - Homeostasis
Leech Neurons Lab Write-Up
Ethical Issue Essay – Exercise in our Nation
Model of a Limb
Major Topic I – Nervous Function
Chapter 13 – The Nervous System
13.1 – Overview of the Nervous System
The nervous system is divided into the central nervous system (CNS) and the peripheral nervous system (PNS). The Nervous system has three functions: 1) reception of input; 2) integration of data; 3) generation of motor input.
Nervous tissue contains two types of cells: neurons and neuroglia. Neurons transmit nerve impulses. Neuroglia nourish and support neurons.
A neuron is composed of dendrites, a cell body, and an axon. There are three types of neurons:
Sensory neurons take nerve impulses from sensory receptors to the CNS. Interneurons occur within the CNS. Motor neurons take nerve impulses from the CNS to effectors (muscle or glands).
Long axons are covered by a myelin sheath.
The Nerve Impulse
Resting Potential – More Na+ outside the axon and more K+ inside the axon. The axon does not conduct an impulse.
Action Potential – A change in polarity across the axonal membrane as a nerve impulse occurs. When Na+ gates open, Na+ moves to the inside of the axon, and a depolarization occurs. When K+ gates open and K+ moves to outside the axon, a repolarization occurs.
The Synapse
When a neurotransmitter is released into a synaptic cleft, transmission of a nerve impulse occurs. Binding of the neurotransmitter to receptors in the receiving membrane causes excitation or inhibition. Integration is the summing of excitatory and inhibitory signals.
13.2 – The Central Nervous System
The CNS receives and integrates sensory input and formulates motor output. The CNS consists of the spinal cord and brain.
The Spinal Cord
Gray matter of the spinal cord contains neuron cell bodies. White matter consists of myelinated axons that occur in tracts. Conduction to and from brain; carries out reflex actions.
The Brain
The cerebrum has two cerebral hemispheres connected by the corpus callosum. Sensation, reasoning, learning and memory, and language and speech take place in the cerebrum. The cerebral cortex of each cerebral hemisphere has four lobes: frontal, parietal, occipital, and temporal. The primary motor area in the frontal lobe sends out motor commands to lower brain centers, which pass them on to motor neurons. The primary somatosensory area in the parietal lobe receives sensory information from lower brain centers in communication with sensory neurons. Association areas are located in all the lobes.
http://science.nationalgeographic.com/science/photos/brain.html
The Diacephalon – The hypothalamus controls homeostasis. The thalamus sends sensory imput on to the cerebrum.
The Cerebellum – the cerebellum coordinates skeletal muscle contractions.
The Brain Stem – The medulla oblongata and the pons have centers for breathing and the heartbeat.
http://science.nationalgeographic.com/science/photos/brain/brain-spinal-cord.html
13.3 – The Limbic System and Higher Mental Functions
The limbic system lying deep in the brain in involved in determining emotions. The amygdale determines when a situation deserves the emotion we call fear. The hippocampus is particularly involved in storing and retrieving memories.
13.4 – The Peripheral Nervous System
The PNS contains only nerves and ganglia. Cranial nerves take impulses to and from the brain. Spinal nerves take impulses to and from the spinal cord. The PNS is divided into the somatic system and the autonomic system.
Somatic System
The somatic system serves the skin, skeletal muscles, and tendons.
• Some actions are due to reflexes, which are automatic and involuntary.
• Other actions are voluntary; originate in cerebral cortex.
Autonomic System
Two divisions in this system are the sympathetic division and the parasympathetic division.
• Sympathetic Division – Responses that occur during times of stress.
• Parasympathetic Division – Responses that occur during times of relaxation.
Actions in these divisions are involuntary and automatic. These divisions innervate internal organs. Two neurons and one ganglion are utilized for each impulse.
13.5 – Drug Abuse
Neurological drugs either promote or prevent the action of a particular neurotransmitter. Dependency occurs when the body compensates for the presence or neurological drugs.
Chapter 14 – Senses
14.1 – Sensory Receptors and Sensations
There are four types of sensory receptors: chemoreceptors, photoreceptors, mechanoreceptors and thermoreceptors.
• Sensory receptors initiate nerve impulses that are transmitted to the spinal cord and/or brain.
• Sensation occurs when nerve impulses reach the cerebral cortex.
• Perception is and interpretation of sensations.
14.2 – Proprioceptors and Cutaneous Receptors
Proprioceptors are mechanoreceptors involved in reflex actions. They help maintain equilibrium and posture.
Cutaneous receptors are found in the skin. They are for touch, pressure, temperature, and pain.
14.3 – Senses of Taste and Smell
Taste and smell are due to chemoreceptors that are stimulated by molecules in the environment.
Sense of taste – Microvilli of taste cells have receptor proteins for molecules that cause the brain to distinguish sweet, sour, salty, and bitter tastes.
Sense of smell – The cilia of olfactory cells have receptor proteins for molecules that cause the brain to distinguish odors.
14.4 – Sense of Vision
Vision depends on the eye, the optic nerves, and the visual areas of the cerebral cortex.
Anatomy and Physiology of the Eye
The eye has three layers:
• The sclera protects and supports the eyeball.
• The choroid absorbs stray light rays
• The retina contains the rod cells and cone cells.
Function of the Lens – The lens (assisted by the cornea and the humors) brings the light rays to focus on the retina. To see a close object, visual accommodation occurs as the lens rounds up.
Visual Pathway to the Brain – The visual pathway begins when light strikes photoreceptors in the retina. The optic nerves carry nerve impulses from the eyes to the optic chiasma, then pass through the thalamus before reaching the primary vision area in the occipital lobe of the brain.
Abnormalities of the eye are blindness, misshapen eyeballs which causes vision abnormalities like nearsightedness, farsightedness, etc.
14.5 – Sense of Hearing
Hearing depends on the ear, the cochlear nerve, and the auditory areas of the cerebral cortex.
Anatomy and Physiology of the Ear
The ear has three parts:
• In the outer ear, the pinna and the auditory canal direct sound waves to the middle ear.
• In the middle ear, the tympanic membrane and the ossicles amplify sound waves.
• In the inner ear, the semicircular canals detect rotational equilibrium; the utricle and saccule detect gravitational equilibrium; and the cochlea houses the spiral organ, which contains mechanoreceptors for hearing.
The auditory pathway begins when the outer ear receives and the middle ear amplifies sound waves that then strike the oval window membrane.
The mechanoreceptors for hearing are hair cells on the basilar membrane of the spiral organ.
Nerve impulses begin in the cochlear nerve and are carried to the primary auditory area in the temporal lobe of the cerebral cortex.
14.6 – Sense of Equilibrium
The ear also contains mechanoreceptors for equilibrium.
Rotational equilibrium pathway - Mechanoreceptors in the semicircular canals detect rotational and/or angular movement of the head.
Gravitational equilibrium pathway – Mechanoreceptors in the utricle and saccule detect head movement in the vertical or horizontal planes.
Major Topic II – Movement
Chapter 11 – The Skeletal System
11.1 – Overview of the Skeletal System
http://www.bio.psu.edu/people/faculty/strauss/anatomy/skel/skeletal.htm
Functions of the skeletal system:
• Supports the body
• Produces blood cells
• Stores mineral salts, particularly calcium phosphate. It also stores fat.
• Along with the muscles, permits flexible body movement.
The bones of the skeleton are composed of bone tissues and cartilage. Ligaments composed of fibrous connective tissue connect bones at joints.
In a long bone:
• Hyaline cartilage covers the ends of a long bone.
• Periosteum covers the rest of the bone
• Spongy bone containing red bone marrow is in the epephyses
• Yellow bone marrow is in the medullary cavity of the diaphysis.
• Compact bone makes up the wall of the diaphysis.
11.2 – Bone Growth, Remodeling and Repair
Cells involved in growth, remodeling, and repair of bone are:
• Osteoblasts, which are bone-forming cells
• Osteocytes, which are mature bone cells derived form osteoblasts, and
• Osteoclasts, which break down and absorb bone.
Bone Development and Growth
• Intramembranous ossification: bones develop between sheets of fibrous connective tissue. Examples are flat bones such as bones of the skull.
• Endochondral ossification: cartilaginous models of the bones are replaced by calcified bone matrix.
• Bone growth is affected by vitamin D, growth hormone, and sex hormones.
Bone Remodeling and Its Role in Homeostasis
• Bone remodeling is the renewal of bone. Osteoclasts break down bone and osteoblasts re-form bone. Some bone is recycled each year.
• Bone recycling allows the body to regulate blood calcium.
Bone Repair
Repair of a fracture requires four steps:
• Hematoma formation,
• Fibrocartilaginous callus
• Bony callus, and
• remodeling
11.3 – Bones of the Axial Skeleton
The axial skeleton consists of the skull, the hybrid bone, the vertebral column and the rib cage.
• The skull is formed by the cranium, which protects the brain and the facial bones.
• The hyoid bone anchors the tongue and is the site of attachment of muscles involved with swallowing.
• The vertebral column is composed of vertebrae separated by shock-absorbing disks, which make the column flexible. It supports the head and trunk, protects the spinal cord, and is a site for muscle attachment.
• The rib cage is composed of the thoracic vertebrae, ribs, costal cartilages, and sternum. It protects the heart and lungs.
11.4 – Bones of the Appendicular Skeleton
The appendicular skeleton consists of the bones of the pectoral girdles, upper limbs, pelvic girdle, and lower limbs.
• The pectoral girdles and upper limbs are adapted for flexibility.
• The pelvic girdle and the lower limbs are adapted for supporting weight; the femur is the longest and strongest bone in the body.
11.5 – Articulations
Bones are joined at joints, of which there are three types:
• Fibrous joints are immovable
• Cartilaginous joints are slightly movable
• Synovial joints are freely moveable
Chapter 12 – The Muscular System
12.1 – Overview of the Muscular System
Human have three types of muscle tissue:
• Smooth muscle is involuntary and occurs in walls of internal organs
• Cardiac muscle is involuntary and occurs in walls of the heart.
• Skeletal muscle is voluntary, contains bundles of muscle fibers called fascicles, and is usually attached by tendons to the skeleton.
Skeletal muscle functions:
• Helps maintain posture
• Provide movement and heat
• Protect underlying organs
Skeletal muscles of the body – when achieving movement, some muscles are prime movers, some are synergists, and others are antagonists.
Names and actions of skeletal muscles – Muscles are named for their size, shape, location, direction of fibers, number of attachments, and action.
12.2 – Skeletal Muscle Fiber Contraction
Muscle fibers contain myofibrils, and myofibrils contain actin and myosin filaments. Muscle contraction occurs when sarcomeres shorten and actin filaments slide past myosin filaments.
• Nerve impulses travel down motor neurons and stimulate muscle fibers at neuromuscular junctions.
• The sarcolemma of a muscle fiber forms T tubules that almost touch the sarcoplasmic reticulum, which stores calcium ions.
• When calcium ions are released into muscle fibers, actin filaments slide past myosin filaments.
• At a neuromuscular junction, synaptic vesicles release acetylcholine, which diffuses across the synaptic cleft.
• When acetylcholine is received by the sarcolemma, impulses begin and lead to the release of calcium.
• Calcium ions bind to troponin, exposing myosin binding sites.
• Myosin filaments break down ATP and attach to actin filaments, forming cross-bridges.
• When ADP and P are released, cross-bridges change their positions.
• This pulls actin filaments to the center of a sarcomere.
12.3 – Whole Muscle Contraction
Muscles Have Motor Units
• A muscle contains motor units: several fibers under the control of a single motor axon.
• Motor unit contraction is described in terms of a muscle twitch, summation, and tetanus.
• The strength of muscle contraction varies according to recruitment of motor units.
• In the body, a continuous slight tension is maintained by muscle motor units that take turns contracting.
Energy for Muscle Contraction
A muscle fiber has three ways to acquire ATP for muscle contraction.
• Creatine phosphate transfers a phosphate to ADP, and ATP results. This CP pathway is the most rapid.
• Fermentation also produces ATP quickly. Fermentation is associated with an oxygen debt because oxygen is needed to metabolize the lactate that accumulates.
• Cellular respiration provides most of the muscle’s ATP, but takes longer because much of the glucose and oxygen must be transported in blood to mitochondria. Cellular respiration occurs during aerobic exercise and burns fatty acids in addition to glucose.
Fast-Twitch and Slow-Twitch Muscle Fibers
• Fast-twitch fibers, for sports like weight lifting, rely on an anaerobic means of axquiring ATP; have few mitochondria and myoglobin, but motor units contain more muscle fibers; and are known for explosive power, but fatigue quickly.
• Slow-twitch fibers, for sports like running and swimming, rely on aerobic respiration to acquire ATP; and have a plentiful supply of mitochondria and myoglobin, which give them a dark color.
12.4 – Muscular Disorders
Muscular disorders include spasms and injuries, as well as diseases such as muscular dystrophy and myasthenia gravis.
12.5 – Homeostasis
• The muscles and bones produce movement and protect body parts.
• The bones produce red blood cells and are involved in the regulation of blood calcium levels.
• The muscles produce the heat that gives us a constant body temperature.
Leech Neurons Lab Write-Up
1. What is the electrode measuring?
The electrode is measuring the action potential of a neuron cell as it is being stimulated by a feather, a probe and forceps.
2. Why use leeches in neurophysiology experiments?
Leeches have very large neuron ganglia that are easy to work with.
3. What is the difference between a sensory and a motor neuron?
A sensory neuron brings information from the skin or extremity to the brain. It allows the brain to interpret feeling and pain. A motor neuron brings information from the brain to an extremity telling it to function.
4. Do you think a leech experiences pain? What is pain?
Leeches must feel pain. In the beginning of the lab, we anesthetized the leech. There would be no reason to do this if it did not feel pain. Pain is the brain’s interpretation of information being brought to it by sensory neurons. It protects us by allowing us to know when something is wrong.
5. What were the two most interesting things about doing this lab?
I like the dissection. I wish I could have done the lab in real life. I also like injecting dye into the cell to see what it looked like under UV light.
6. Anything you found confusing or didn't like about the lab?
I didn’t like the fact that I couldn’t actually control the tools. I was only able to click and let the computer do the work.
Ethical Issue Essay – Exercise in our Nation
Exercise is a real problem in this country. Our bodies were designed to work hard, but due to the way our race has evolved, there are less and less opportunities to use our bodies for physical labor. After researching websites for other countries, it seems that the problem is world-wide. Transportation, elevators, computers, even air conditioning has contributed to our decline of health. The question is though, should we rid ourselves of these achievements to gain in health? I believe the answer is no. The answer should be more education.
I liked Hong Kong’s website (silly as it was) on nutrition and exercise. They even had a page that provided education on breast-feeding. Our society has become so liberal about alternative choices, that we neglect what nature has provided us.
Instead of reverting back to a low-tech society, we should be teaching our children a smarter way to live. Exercise as a family and set limits on television time. Don’t allow your children to sit in a stupor in front of video games for hours on end. Try not to purchase many food products that are filled with chemicals and words that are not easily pronounced. These foods are normally junk foods and frozen meals.
In elementary school, Health class should be more comprehensive and it should follow into high school. If good habits can be built in our children, those habits are more likely to follow as adults.
Model of a Limb
Chapter 13 – The Nervous System
13.1 – Overview of the Nervous System
13.2 – The Central Nervous System
13.3 – The Limbic System and Higher Mental Functions
13.4 – The Peripheral Nervous System
13.5 – Drug Abuse
Chapter 14 – Senses
14.1 – Sensory Receptors and Sensations
14.2 – Proprioceptors and Cutaneous Receptors
14.3 – Senses of Taste and Smell
14.4 – Sense of Vision
14.5 – Sense of Hearing
14.6 – Sense of Equilibrium
Chapter 11 – The Skeletal System
11.1 – Overview of the Skeletal System
11.2 – Bone Growth, Remodeling and Repair
11.3 – Bones of the Axial Skeleton
11.4 – Bones of the Appendicular Skeleton
11.5 - Articulations
Chapter 12 – The Muscular System
12.1 – Overview of the Muscular System
12.2 – Skeletal Muscle Fiber Contraction
12.3 – Whole Muscle Contraction
12.4 – Muscular Disorders
12.5 - Homeostasis
Leech Neurons Lab Write-Up
Ethical Issue Essay – Exercise in our Nation
Model of a Limb
Major Topic I – Nervous Function
Chapter 13 – The Nervous System
13.1 – Overview of the Nervous System
The nervous system is divided into the central nervous system (CNS) and the peripheral nervous system (PNS). The Nervous system has three functions: 1) reception of input; 2) integration of data; 3) generation of motor input.
Nervous tissue contains two types of cells: neurons and neuroglia. Neurons transmit nerve impulses. Neuroglia nourish and support neurons.
A neuron is composed of dendrites, a cell body, and an axon. There are three types of neurons:
Sensory neurons take nerve impulses from sensory receptors to the CNS. Interneurons occur within the CNS. Motor neurons take nerve impulses from the CNS to effectors (muscle or glands).
Long axons are covered by a myelin sheath.
The Nerve Impulse
Resting Potential – More Na+ outside the axon and more K+ inside the axon. The axon does not conduct an impulse.
Action Potential – A change in polarity across the axonal membrane as a nerve impulse occurs. When Na+ gates open, Na+ moves to the inside of the axon, and a depolarization occurs. When K+ gates open and K+ moves to outside the axon, a repolarization occurs.
The Synapse
When a neurotransmitter is released into a synaptic cleft, transmission of a nerve impulse occurs. Binding of the neurotransmitter to receptors in the receiving membrane causes excitation or inhibition. Integration is the summing of excitatory and inhibitory signals.
13.2 – The Central Nervous System
The CNS receives and integrates sensory input and formulates motor output. The CNS consists of the spinal cord and brain.
The Spinal Cord
Gray matter of the spinal cord contains neuron cell bodies. White matter consists of myelinated axons that occur in tracts. Conduction to and from brain; carries out reflex actions.
The Brain
The cerebrum has two cerebral hemispheres connected by the corpus callosum. Sensation, reasoning, learning and memory, and language and speech take place in the cerebrum. The cerebral cortex of each cerebral hemisphere has four lobes: frontal, parietal, occipital, and temporal. The primary motor area in the frontal lobe sends out motor commands to lower brain centers, which pass them on to motor neurons. The primary somatosensory area in the parietal lobe receives sensory information from lower brain centers in communication with sensory neurons. Association areas are located in all the lobes.
http://science.nationalgeographic.com/science/photos/brain.html
The Diacephalon – The hypothalamus controls homeostasis. The thalamus sends sensory imput on to the cerebrum.
The Cerebellum – the cerebellum coordinates skeletal muscle contractions.
The Brain Stem – The medulla oblongata and the pons have centers for breathing and the heartbeat.
http://science.nationalgeographic.com/science/photos/brain/brain-spinal-cord.html
13.3 – The Limbic System and Higher Mental Functions
The limbic system lying deep in the brain in involved in determining emotions. The amygdale determines when a situation deserves the emotion we call fear. The hippocampus is particularly involved in storing and retrieving memories.
13.4 – The Peripheral Nervous System
The PNS contains only nerves and ganglia. Cranial nerves take impulses to and from the brain. Spinal nerves take impulses to and from the spinal cord. The PNS is divided into the somatic system and the autonomic system.
Somatic System
The somatic system serves the skin, skeletal muscles, and tendons.
• Some actions are due to reflexes, which are automatic and involuntary.
• Other actions are voluntary; originate in cerebral cortex.
Autonomic System
Two divisions in this system are the sympathetic division and the parasympathetic division.
• Sympathetic Division – Responses that occur during times of stress.
• Parasympathetic Division – Responses that occur during times of relaxation.
Actions in these divisions are involuntary and automatic. These divisions innervate internal organs. Two neurons and one ganglion are utilized for each impulse.
13.5 – Drug Abuse
Neurological drugs either promote or prevent the action of a particular neurotransmitter. Dependency occurs when the body compensates for the presence or neurological drugs.
Chapter 14 – Senses
14.1 – Sensory Receptors and Sensations
There are four types of sensory receptors: chemoreceptors, photoreceptors, mechanoreceptors and thermoreceptors.
• Sensory receptors initiate nerve impulses that are transmitted to the spinal cord and/or brain.
• Sensation occurs when nerve impulses reach the cerebral cortex.
• Perception is and interpretation of sensations.
14.2 – Proprioceptors and Cutaneous Receptors
Proprioceptors are mechanoreceptors involved in reflex actions. They help maintain equilibrium and posture.
Cutaneous receptors are found in the skin. They are for touch, pressure, temperature, and pain.
14.3 – Senses of Taste and Smell
Taste and smell are due to chemoreceptors that are stimulated by molecules in the environment.
Sense of taste – Microvilli of taste cells have receptor proteins for molecules that cause the brain to distinguish sweet, sour, salty, and bitter tastes.
Sense of smell – The cilia of olfactory cells have receptor proteins for molecules that cause the brain to distinguish odors.
14.4 – Sense of Vision
Vision depends on the eye, the optic nerves, and the visual areas of the cerebral cortex.
Anatomy and Physiology of the Eye
The eye has three layers:
• The sclera protects and supports the eyeball.
• The choroid absorbs stray light rays
• The retina contains the rod cells and cone cells.
Function of the Lens – The lens (assisted by the cornea and the humors) brings the light rays to focus on the retina. To see a close object, visual accommodation occurs as the lens rounds up.
Visual Pathway to the Brain – The visual pathway begins when light strikes photoreceptors in the retina. The optic nerves carry nerve impulses from the eyes to the optic chiasma, then pass through the thalamus before reaching the primary vision area in the occipital lobe of the brain.
Abnormalities of the eye are blindness, misshapen eyeballs which causes vision abnormalities like nearsightedness, farsightedness, etc.
14.5 – Sense of Hearing
Hearing depends on the ear, the cochlear nerve, and the auditory areas of the cerebral cortex.
Anatomy and Physiology of the Ear
The ear has three parts:
• In the outer ear, the pinna and the auditory canal direct sound waves to the middle ear.
• In the middle ear, the tympanic membrane and the ossicles amplify sound waves.
• In the inner ear, the semicircular canals detect rotational equilibrium; the utricle and saccule detect gravitational equilibrium; and the cochlea houses the spiral organ, which contains mechanoreceptors for hearing.
The auditory pathway begins when the outer ear receives and the middle ear amplifies sound waves that then strike the oval window membrane.
The mechanoreceptors for hearing are hair cells on the basilar membrane of the spiral organ.
Nerve impulses begin in the cochlear nerve and are carried to the primary auditory area in the temporal lobe of the cerebral cortex.
14.6 – Sense of Equilibrium
The ear also contains mechanoreceptors for equilibrium.
Rotational equilibrium pathway - Mechanoreceptors in the semicircular canals detect rotational and/or angular movement of the head.
Gravitational equilibrium pathway – Mechanoreceptors in the utricle and saccule detect head movement in the vertical or horizontal planes.
Major Topic II – Movement
Chapter 11 – The Skeletal System
11.1 – Overview of the Skeletal System
http://www.bio.psu.edu/people/faculty/strauss/anatomy/skel/skeletal.htm
Functions of the skeletal system:
• Supports the body
• Produces blood cells
• Stores mineral salts, particularly calcium phosphate. It also stores fat.
• Along with the muscles, permits flexible body movement.
The bones of the skeleton are composed of bone tissues and cartilage. Ligaments composed of fibrous connective tissue connect bones at joints.
In a long bone:
• Hyaline cartilage covers the ends of a long bone.
• Periosteum covers the rest of the bone
• Spongy bone containing red bone marrow is in the epephyses
• Yellow bone marrow is in the medullary cavity of the diaphysis.
• Compact bone makes up the wall of the diaphysis.
11.2 – Bone Growth, Remodeling and Repair
Cells involved in growth, remodeling, and repair of bone are:
• Osteoblasts, which are bone-forming cells
• Osteocytes, which are mature bone cells derived form osteoblasts, and
• Osteoclasts, which break down and absorb bone.
Bone Development and Growth
• Intramembranous ossification: bones develop between sheets of fibrous connective tissue. Examples are flat bones such as bones of the skull.
• Endochondral ossification: cartilaginous models of the bones are replaced by calcified bone matrix.
• Bone growth is affected by vitamin D, growth hormone, and sex hormones.
Bone Remodeling and Its Role in Homeostasis
• Bone remodeling is the renewal of bone. Osteoclasts break down bone and osteoblasts re-form bone. Some bone is recycled each year.
• Bone recycling allows the body to regulate blood calcium.
Bone Repair
Repair of a fracture requires four steps:
• Hematoma formation,
• Fibrocartilaginous callus
• Bony callus, and
• remodeling
11.3 – Bones of the Axial Skeleton
The axial skeleton consists of the skull, the hybrid bone, the vertebral column and the rib cage.
• The skull is formed by the cranium, which protects the brain and the facial bones.
• The hyoid bone anchors the tongue and is the site of attachment of muscles involved with swallowing.
• The vertebral column is composed of vertebrae separated by shock-absorbing disks, which make the column flexible. It supports the head and trunk, protects the spinal cord, and is a site for muscle attachment.
• The rib cage is composed of the thoracic vertebrae, ribs, costal cartilages, and sternum. It protects the heart and lungs.
11.4 – Bones of the Appendicular Skeleton
The appendicular skeleton consists of the bones of the pectoral girdles, upper limbs, pelvic girdle, and lower limbs.
• The pectoral girdles and upper limbs are adapted for flexibility.
• The pelvic girdle and the lower limbs are adapted for supporting weight; the femur is the longest and strongest bone in the body.
11.5 – Articulations
Bones are joined at joints, of which there are three types:
• Fibrous joints are immovable
• Cartilaginous joints are slightly movable
• Synovial joints are freely moveable
Chapter 12 – The Muscular System
12.1 – Overview of the Muscular System
Human have three types of muscle tissue:
• Smooth muscle is involuntary and occurs in walls of internal organs
• Cardiac muscle is involuntary and occurs in walls of the heart.
• Skeletal muscle is voluntary, contains bundles of muscle fibers called fascicles, and is usually attached by tendons to the skeleton.
Skeletal muscle functions:
• Helps maintain posture
• Provide movement and heat
• Protect underlying organs
Skeletal muscles of the body – when achieving movement, some muscles are prime movers, some are synergists, and others are antagonists.
Names and actions of skeletal muscles – Muscles are named for their size, shape, location, direction of fibers, number of attachments, and action.
12.2 – Skeletal Muscle Fiber Contraction
Muscle fibers contain myofibrils, and myofibrils contain actin and myosin filaments. Muscle contraction occurs when sarcomeres shorten and actin filaments slide past myosin filaments.
• Nerve impulses travel down motor neurons and stimulate muscle fibers at neuromuscular junctions.
• The sarcolemma of a muscle fiber forms T tubules that almost touch the sarcoplasmic reticulum, which stores calcium ions.
• When calcium ions are released into muscle fibers, actin filaments slide past myosin filaments.
• At a neuromuscular junction, synaptic vesicles release acetylcholine, which diffuses across the synaptic cleft.
• When acetylcholine is received by the sarcolemma, impulses begin and lead to the release of calcium.
• Calcium ions bind to troponin, exposing myosin binding sites.
• Myosin filaments break down ATP and attach to actin filaments, forming cross-bridges.
• When ADP and P are released, cross-bridges change their positions.
• This pulls actin filaments to the center of a sarcomere.
12.3 – Whole Muscle Contraction
Muscles Have Motor Units
• A muscle contains motor units: several fibers under the control of a single motor axon.
• Motor unit contraction is described in terms of a muscle twitch, summation, and tetanus.
• The strength of muscle contraction varies according to recruitment of motor units.
• In the body, a continuous slight tension is maintained by muscle motor units that take turns contracting.
Energy for Muscle Contraction
A muscle fiber has three ways to acquire ATP for muscle contraction.
• Creatine phosphate transfers a phosphate to ADP, and ATP results. This CP pathway is the most rapid.
• Fermentation also produces ATP quickly. Fermentation is associated with an oxygen debt because oxygen is needed to metabolize the lactate that accumulates.
• Cellular respiration provides most of the muscle’s ATP, but takes longer because much of the glucose and oxygen must be transported in blood to mitochondria. Cellular respiration occurs during aerobic exercise and burns fatty acids in addition to glucose.
Fast-Twitch and Slow-Twitch Muscle Fibers
• Fast-twitch fibers, for sports like weight lifting, rely on an anaerobic means of axquiring ATP; have few mitochondria and myoglobin, but motor units contain more muscle fibers; and are known for explosive power, but fatigue quickly.
• Slow-twitch fibers, for sports like running and swimming, rely on aerobic respiration to acquire ATP; and have a plentiful supply of mitochondria and myoglobin, which give them a dark color.
12.4 – Muscular Disorders
Muscular disorders include spasms and injuries, as well as diseases such as muscular dystrophy and myasthenia gravis.
12.5 – Homeostasis
• The muscles and bones produce movement and protect body parts.
• The bones produce red blood cells and are involved in the regulation of blood calcium levels.
• The muscles produce the heat that gives us a constant body temperature.
Leech Neurons Lab Write-Up
1. What is the electrode measuring?
The electrode is measuring the action potential of a neuron cell as it is being stimulated by a feather, a probe and forceps.
2. Why use leeches in neurophysiology experiments?
Leeches have very large neuron ganglia that are easy to work with.
3. What is the difference between a sensory and a motor neuron?
A sensory neuron brings information from the skin or extremity to the brain. It allows the brain to interpret feeling and pain. A motor neuron brings information from the brain to an extremity telling it to function.
4. Do you think a leech experiences pain? What is pain?
Leeches must feel pain. In the beginning of the lab, we anesthetized the leech. There would be no reason to do this if it did not feel pain. Pain is the brain’s interpretation of information being brought to it by sensory neurons. It protects us by allowing us to know when something is wrong.
5. What were the two most interesting things about doing this lab?
I like the dissection. I wish I could have done the lab in real life. I also like injecting dye into the cell to see what it looked like under UV light.
6. Anything you found confusing or didn't like about the lab?
I didn’t like the fact that I couldn’t actually control the tools. I was only able to click and let the computer do the work.
Ethical Issue Essay – Exercise in our Nation
Exercise is a real problem in this country. Our bodies were designed to work hard, but due to the way our race has evolved, there are less and less opportunities to use our bodies for physical labor. After researching websites for other countries, it seems that the problem is world-wide. Transportation, elevators, computers, even air conditioning has contributed to our decline of health. The question is though, should we rid ourselves of these achievements to gain in health? I believe the answer is no. The answer should be more education.
I liked Hong Kong’s website (silly as it was) on nutrition and exercise. They even had a page that provided education on breast-feeding. Our society has become so liberal about alternative choices, that we neglect what nature has provided us.
Instead of reverting back to a low-tech society, we should be teaching our children a smarter way to live. Exercise as a family and set limits on television time. Don’t allow your children to sit in a stupor in front of video games for hours on end. Try not to purchase many food products that are filled with chemicals and words that are not easily pronounced. These foods are normally junk foods and frozen meals.
In elementary school, Health class should be more comprehensive and it should follow into high school. If good habits can be built in our children, those habits are more likely to follow as adults.
Model of a Limb
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