Treppe Contraction

The treppe contraction is the staircase effect. Graded contractions acummulate because calcium hasn't been absorbed , this causes a graded response . A single stimulus that produces a twitch and the stimulus gets greater ; muscles are warmer and enzymes are more efficient ;  calcium remains in the sarcoplasm and is not all taken up into the sacoplasmic recticulum.

Events That Occur During Each Phase of a Muscle Twitch

Lag Phase : 1] An action potential is progated to the presynatic terminal of the motor neuron.. 2] The action potention causes the permeability of the presynaptic terminal to increase. 3] Calcium ions diffuse into the presynaptic teminal , causing acetylcholine contained within several synaptic vesicles to be released by exocytosis intso the synaptic cleft. 4]Acetylcholine released from the presynaptic terminal diffuses across the synaptic sleft and binds to acetylcholine receptor molecules in the postsynaptic membrame  of the sarcolemma . 5] The binding of acetylcholine to its receptor site causes ligand-gated Na+ channels to open ,and the postsynaptic membrane becomes more permeable to Na+. 6 ] Sodium ions difuse into muscle fiber ,causing a local depolarization that exceeds threshold and produces an action potential .7] Acetycholine is rapidly degraded in the synaptic cleft to acetic acid and choline by acetylcholinesterase , thus limiting the length of  time acetylcholine is bound to its reptor site .The result is that one presynpatic action potential produces one postsynaptic action potential in each muscle fiber . 8] The action potentia produced in a muscle fiber is progated from the postsynaptic membrane near the middle of both ends and into the T tububles .9] The depolarization that occurs in the the T tubule in response to the actio potential causes Ca+ channels of the membrane of the membrane of the sarcoplasmic recticulum to open ,and the membrane of the sarcoplasmic recticulum becomes very permeable to Ca2+. 10] Calcium ions diffuse from the sacroplasplasmic recticulum into the sacrcoplasm. 11] Calcium ions bind troponin ; The troponin -tropomyosin complex changes its postionand exposes the active site on the on the acttin myofilaments.
Contraction Phase
12 ]Cross- bridges  between actin molecules and myosin molecules form, move , release ,and reform many  times , causing the sarcomeres to shorten . Energy stored in the head of the myosin molecule allows cross-bridge formation and movements. After cross-bridge movement has occurred  ,ATP must bind to myosin head . The ATP is broke down to ADP , and some of the energy is used to released the cross-bridge  and cause the head of the myosin molecule to move back to it's resting postion , where its ready to form another cross-bridge . Some of the energy from the ATP is stored in the myosin head and is used for the next cross-bridge formationand monement.
Relaxation Phase
13] Calcium ions are actively transported into the sacoplasmic reticulum .
14] The trponin-tropomyosin complexes inhibit cross-bridge formation.
15] The muscle fibers lengthen passively .

The Skeletal System

I learned in the skeletal system that the bone cells osteocytes  maintain matrix within the lucunae.Osteoblasts deposit matrix , and when they get caught  become osteocytes. Osteoblasts come from osteochondral progenitor cells  , which comes from mesenchymal cells  all cells resposible for making connective tissue. Osteoclasts break down nbone , secrete water , make hydrochloric acid , breaks down collagen fibers . Precursor cells are monocytes ,which phagocyte , andand become become" big eaters" nacrophages. Cells that produce cartilage are chondoblasts ,and are trapped inside and become chondrocytes .The job of the chondrocytes is to maintain cartilage . In the bone matrix the inorganic material consists primarily of hydroxyapatite . The organic molecules has two things C02 ,and H2 .Collagen is a lipid , a big molecule, subunit protein anino acid is 20.Collagen -amino acids are all organic.The function of the skeletal system is to support , to hold the body up ,prtection of all major organs , movement , and storage . I learned there are two types of cartilage ; hyaline  , and fibrocartilage . Fibrocartililage is found in the intervebral discs ,sympyhsis ,balland socket / glenoid cavity . The hyaline cartilage can be found in in the synovial joints , slick surfaces , epephyses paltes , long bones ,synchondroses ,bends ,ribs to sternum . We grow cartilage byinterstitial and appositional growth .Interstitial , catilage replicates, , appositional  , chondroblasts add new cartilage to the outside of the cartilage .I learned the two tyoes of bone growth , intramembranous ossification , and endochondral ossification . Intramembranous growth takes palce within the connnective tissue membrane , while the endochondral ossification takes palcein the cartialage .Both methods produce woven bone , which is then remodeled .

Tisssues and Muscles

I've learned in lab regarding the tissues that the simple squamous epithelium is located in the kidney glomeruli , it's job is to line , cover , filter , and produce serous fluid. It .lines the mesothelium cavity that encloses the organs such as the heart , abdomen and lung . The  simple cuboidal epithelium is located in the kidney tubules , it's function is secretion and absorption. The simple columnar epithelium lines the intestines , job is secretion and absorption . The pseudostratified columnar epithelium moves stuff out of trachea , secretes particularly mucous .The transitional epithelium  tissue is ballooned shaped ,streches to accomadate storage of urine . It lines the ureters , urinary bladder,and part of the urethra .The loose areolar connective tissue consists of looose collection of cells with lots of space .This tissue anchors dermis , epidermis papillary layer .The hyaline cartilage covers the end of long bones ,chronoblasts produce the matrix and when mature chrondrocytes lie in the lucunae .Elastic cartilage supprts the external ear , maintaining the structure while allowing flexibility .The fibrocartilage is located between the interverbral discs , cushions between bones .The compact bone supports , and protects , the osteocytes lie in the lucunae. The pacinian corpuscles lie in the hypodemis ,it's function is deep cutaneous pressure , and vibration. Arranged like leaves of an onion .The integumentary is the skin which has several layers , including the luciden . The scalp  which consists of the hair follicles , with the arrector pili muscle, sebacous glands and sweat glands . The multipolar cell , the nervous tissue consists of motor neurons ,glia cells and other large cells .The retina consisted of the fibrous coat ,sclera ,cornea ,the cell body , rods ,and cones , and ganglion cells .The skeletal muscle  is elongated contiuous fibers , with nucleated striations . The cardiac muscle has a hugh number of thin cells , spindled shaped with overlapping ends . It contracts , and propels blood into circulation .

The Classes of Joints

I learned in class on yesterday from Chap. 8 ,the concept of the classes of joints . An ex. of an fibrous joint is sutures of the skull . Cartilaginous joints have cartilage , and are in the ribs .The synovial joints contains synovial fluid covered with hyaline cartilage called articular cartilage which provides smooth surface where the bone surface . The function of the synarthroses =no movement. Amphiathroses =little movement ,and diathroses =means free movement .

Action of an Odorant Binding to Menbrame of Olfactory Hair /Chap 15

I learned the concept of that airborne molecules enter the nasal cavity and are dissolved in the fluid covering the olfactory epithelium .These molecules are are odorants . The plasma membrane of the olfactory hair , unstimulated , the gate stys closed . An odorant binds to a receptor ,activating the "G" protein . The a ,B,and y come aloose , the" a"  subunit binds to and activates adeny;late cyclase.Adenylate cyclase catalyzes the conversion of ATP to AMP[cAMP] .cAMP opens the ion channels , such as sodium and calcium . Ions cause depolarization of the nueron . This is what causes us to be able smell so many different things.

The Location of the ANS receptors

When you had the class to break off into groups and help each other to learn the location of the ANS receptors , was very helpful .The drawing on the board demostrated that 1] the somatic nerve which the skeletal is the target has one synaspe releases ACH ,which binds to a nicotinic receptor. 2] The autonomic nerve releases ACH to the adrenal gland  , then releases epinephrine and norepinephrine into the bloodstream. 3] The sympathetic division releases ACH causes NE , which relaeases norepinephrine into the adrenal glands . 4] Then there's the parasympathetic division that releases ACH muscarinic is released into the heart . I've learned that  the sympathetic and parasympathetic  neve endings one of the two transmitters. If it secretes ACH it 's a cholinergic , if it secretes norepinephrine it's an adrenergic neuron . I see how they play the neurotransmittor role .