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This 8 page Class Notes was uploaded by Falyn Ruby on Tuesday February 23, 2016. The Class Notes belongs to BIO 1004 at Mississippi State University taught by Jeffery Echols in Spring 2016. Since its upload, it has received 56 views. For similar materials see Anatomy & Physiology in Biology at Mississippi State University.
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Date Created: 02/23/16
Anatomy and Physiology Chapter 7 Notes The Muscular System Muscle groups to know: o Frontalis, trapezius, deltoid, pectoralis major, triceps, brachii, latissimus dorsi, abdominal muscles, gluteus maximus, Sartorius, biceps femoris, rectus femoris, gastrocnemius There are three types of muscle tissue: striated cardiac muscle, striated skeletal muscle, and smooth muscle. o The only thing a muscle cell can do is contract and relax. Calcium and an electrical stimulation is necessary for muscle contraction. o Smooth muscle Smooth muscle cells are spindle shaped and taper towards the end. Smooth muscle is found in hollow internal organs such as the digestive tract, stomach, esophagus, veins and arteries, reproductive system, etc. The muscle contracts to move materials through hollow internal organs. Characteristics of smooth muscle: Form sheets One nucleus per cell Lacks striations Involuntary Contracts slowly Fatigues slowly o Cardiac Muscle Cardiac muscle is the only muscle that will completely rest after a contraction. It is only found in the heart. Characteristics: Branched structure Deeply striated Involuntary (not controlled by the brain) o Pacemaker cells cause contractions Non-fatiguing Individual muscle cells are fused together o Skeletal Muscle Characteristics: Cylindrical Striations Multinucleated Cells occur in bundles Attached to bone Functions of skeletal muscle Supports the body Allows for movement of the bones Maintains a normal body temperature o Produces heat during contractions shivering: uncontrolled muscle contraction o Moves blood in veins Can provide some insulation to protect Protects internal organs Stabilizes joints (along with ligaments) Moves lymph in lymphatic vessels Structure: A muscle is covered by a layer of connective tissue called the fascia, which tapers to form tendons. Tendons connect muscles to bones. Ligaments connect bone to bone. Muscle bundles are fibers enclosed in connective tissue. A muscle fiber is a group of myofibrils surrounded by connective tissue. (Groups of muscle fibers form a muscle bundle.) o A myofibril is the functional unit of a muscle that contains actin and myosin. When actin and myosin slide past one another, the myofibrils contract. There are two types of proteins associated with muscles: o Actin o Myosin During a muscle contraction, actin and myosin fibers form temporary chemical bonds causing the myofibrils to shorten and the muscle to contract. o Temporary chemical bonds form only when an electrical impulse, calcium, and ATP are present. ATP is the energy source needed for a chemical bond to form. (formed in mitochondria) Muscle tissues contain a lot of mitochondria. The temporary bonds are broken when the electrical impulse disappears which allows the myofibrils and the muscle to relax. The energy from breaking the temporary bond between actin and myosin is released as heat and distributed by the blood. Muscle contraction is the contraction of numerous myofibrils, which depends on the frequency of electrical impulses from the nervous system. Contraction requires an electrical stimulation, calcium, and ATP. Myoglobin stores oxygen in the muscle tissue. Glycogen is a carb that provides the glucose necessary to make ATP. Creatine Phosphate aids in regeneration of ATP. o Quickly replaces the phosphate that is broken off. Fermentation is the process of making ATP without oxygen, which leads to a buildup of lactic acid near the joints. o Lactic acid makes nerve endings more sensitive which can cause pain. o Athletics Atrophy is the shrinkage of muscles due to not using them. If you do not use your muscles over a long period of time, the muscle is replaced with connective and adipose tissue. o May lead to contortion of body parts. Hypertrophy is the enlargement of muscles due to increased use and increased number of myofibrils. o Muscles must be worked to 75% of maximum and worked on a continuous basis. Steroids o The good aspects: promote healing and allow muscles to recover faster during injury. o The bad aspects: Men: Develop enlarged muscles, increased body hair, reduced scalp hair, persistent acne, shrinkage of testicles, mood swings. Most symptoms disappear after ceasing use. Women: Decrease in breast tissue, deepening of the voice, facial features become masculinized, reproductive cycle stops, external genitalia become enlarged. None of the symptoms are reversible. o Types of myofibrils: Slow twitch – provide endurance, slow to fatigue, darker in color (myoglobin,) greater blood supply, aerobic Females have more slow twitch fibers than males. AKA females have more endurance. Fast Twitch – provide explosive strength, quick to fatigue, light in color, less blood supply, anaerobic (energy from ATP.) o Basic Terminology Origin – muscle ties into a non-moving bone Insertion – muscle ties into a moving bone Prime-mover – large muscle group that provides most of the power. Synergists – small muscles that provide additional power during a movement and provide stability during a movement. Antagonists - muscles occur in pairs. EX: Biceps and triceps – opposite movements In order to function effectively, one member of the pair must relax while the other contracts. Cerebellum controls antagonistic pairs. Anatomy and Physiology Chapter 8 Nervous System Nervous System o The function of the nervous system is communication through electrical impulses. o The nervous system is divided into two parts: the central and peripheral. The central nervous system consists of the brain and spinal cord. The peripheral nervous system consists of everything else that is a neuron and neuroglial cells. The PNS is more extensive than the CNS. o A neuron is capable of generating and conducting an electrical impulse. Parts of the neuron: The cell body contains the nucleus and most of the organelles. Dendrites (cytoplasmic extensions) form a connection with neighboring neurons and they receive an electrical impulse. o Can connect to numerous other neurons. Axons are cytoplasmic extensions from the cell body that conduct electrical impulses to the dendrites of neighboring neurons. o They can connect to numerous other neurons. The flow of electricity through a neuron starts at the dendrites and flows through the cell body and into the axons. Types of Neurons: Sensory neurons are associated with the special senses and are capable of generating an electrical impulse and conducting that impulse toward the brain. Motor Neurons are incapable of generating an electrical impulse. They normally conduct electrical impulses from the brain to the muscle. (supply the electrical impulse for muscle contraction) o Serve both skeletal and smooth muscle Interneurons are found mainly in the brain, receive inpulses from the sensory neurons then perform integration, and send impulses to the muscles through the motor neurons. o Neuroglial cells provide protection, physical support, and nutritional support. Schwann cells are smaller than neurons and attach to the axons. They produce a protein called myelin which speeds up electrical impulses. Oligodendrocytes attach to the axons and produce a protein called myelin. o Nerve impulses The synaptic cleft is a gap where axons connect to the adjacent neuron. Impulses do not cross empty gaps. Chemicals are released from the axons of one neuron. They briefly fill the synaptic gap, which allows the electrical impulse to pass. They are quickly reabsorbed by the receiving neuron. Neurotransmitters are absorbed into vesicles and transported to the axons of the receiving neuron. o The spinal cord is a hollow tube that is open at both ends and made up of mostly motor neurons which serve skeletal muscle. The spinal cord does not contain some sensory neurons. It is made up of gray matter that is concentrated in a central region made up of cell bodies and neurons. White matter is made up of axons and dendrites and surrounds the outer region. The spinal cord has numerous connections to the peripheral nervous system. It is also surrounded by a protective covering called meninges. Surround the brain and spinal cord Meningitis – infection in the meninges. (can be deadly) Cerebrospinal fluid is produced in the brain and travels through the central opening forming a protective area between the spinal cord and the meninges. Should be sterile because it protects the brain and spinal cord. o The brain stem is made up of 3 parts: The medulla regulates heartbeat, breathing rate, blood pressure, vomiting, coughing, sneezing, hiccups, and swallowing. The pons is the enlarged area of the brain stem that is a connecting point between the cerebellum and the spinal cord. It is also involved in breathing rate and controls head movements in response to visual and auditory stimulation. The midbrain is part of the brainstem that shares some of the same function as the pons. o The diencephalon is the central core of the brain. It is located below the cerebrum and above the brain stem. Divided into 2 parts: The thalamus is a central relay station for the rest of the brain. The hypothalamus maintains homeostasis and serves as the link between the nervous system and endocrine system. o Homeostasis consists of water balance in the blood, hunger, thirst, body temperature, influences blood pressure, and produces hormones. o The cerebellum is responsible for muscle coordination, posture, muscle tone, and controls which member of an antagonistic pair relaxes and which member contracts. Divided into hemispheres. o The cerebrum is in control of conscious thought and memory. It is divided into hemispheres. Contains hills and valleys in physical appearance. Gyri are the raised areas in the cerebrum. Sucli are the shallow areas in the cerebrum. Contains fissures, which are deep cracks that almost completely divide the brain. A comparison of brain size to body mass is a good indicator of intelligence in different species. The limbic system is in control of memory based on emotions, and it is often poorly understand. o Ventricles are filled with cerebrospinal fluid, which protects the brain from concussion and helps maintain the brain’s shape. There are four ventricles that produce cerebrospinal fluid, are interconnected, and connected to the central canal of the spinal cord. The two largest ventricles are: o Right ventricle o Left ventricle The third ventricle is smaller and located in the diencephalon. The fourth ventricle is the smallest and is located in the brain stem. o Peripheral nervous system The somatic nervous system contains cranial nerves, connects the sense organs directly to the brain, and does not connect to the spinal cord. Cranial nerves are connected to the brain and come in pairs. Spinal nerves are generally connected to the skeletal muscle and connects to the spinal cord. Cranial nerves consist of optic nerves, olfactory nerves, facial motor nerves, and the vagus nerve. o The vagus nerve is a cranial nerve that branches to all of the internal organs and controls them. Autonomic Nervous System Sympathetic division controls your body during times of stress, causes muscle to contract more forcible, and release hormones. o vision and hearing becomes more acute o stops the action of smooth muscle Parasympathetic controls body functions during times of low stress.