BIOL 235 midterm 2 Biology practice exam questions and answers

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Assignment 2 Weight: 5% Minimum Pass Grade: 50% Each question is worth 10 marks. 1. Name the type of joint, and list the movements permitted at the shoulder joint. Under each movement’s name, lis ... t the names of the muscles responsible for each of these movements along with descriptions of their bone insertion. The glenohumoral joint (shoulder joint) is a ball and socket joint formed by the head of the humerus and the glenoid cavity of the scapula, composed of a synovial cavity united by dense irregular connective tissue of an articular capsule and accessory ligaments. This is the most mobile joints in the human body, being the most mobile this comes at the cost of stability. This synovial, diarthodial joint has freedom of movement due to the looseness of the articular capsule and the shallowness of the glenoid cavity in relation to the large size of the head of the humerus. i. Extension – upward movement of the humerus on the glenoid in the sagittal plane towards the rear of the body. a. Latissimus dorsi, inserts on the intertubercular sulcus of humerus b. Deltoid (posterior fibers), inserts on deltoid tuberosity of humerus c. Teres major, inserts on the medial lip of intertubercular sulcus of humerus d. Teres minor , inserts on the greater tubercle of humerus e. Triceps brachii, inserts on the olecranon of ulna ii. Flexion - Forward and upward movement of the humerus on the glenoid in the sagittal plane. a. Deltoid (anterior fibers), insert in deltoid tuberosity b. Coracobrachialis , inserts on the medial surface of shaft of humerus c. Biceps Brachii, inserts on radial tuberosity of radius and bicipital aponeurosis iii. Abduction - Elevation of the humerus on the glenoid in the frontal (coronal) plane. a. Deltoid (lateral fibers), inserts on the deltoid tuberosity of humerus b. Supraspinatus, insert on the greater tubercle of humerus iv. Adduction - Movement of the humerus on the glenoid in a medial direction, usually accompanied with some degree of shoulder flexion a. Pectoralis Major, inserts on the greater tubercle and lateral lip of intertubercular sulcus of humerus b. Latissimus dorsi, inserts on the intertubercular sulcus of humerus c. Teres Major, inserts on the medial lip of the intertubercular sulcus of humerus v. Medial Rotation a. Pectoralis Major, inserts on the greater tubercle and lateral lip of intertubercular sulcus of humerus b. Latissimus dorsi, inserts on the intertubercular sulcus of humerus c. Deltoid (anterior fibers), inserts on the deltoid tuberosity of humerus d. Subscapularis, inserts on the lesser tubercle of humerus e. Teres major, inserts on the medial lip of intertubercular sulcus of humerus vi. Lateral Rotation a. Deltoid (posterior fibers), inserts on the deltoid tuberosity of humerus b. Infraspinatus , inserts on the greater tubercle of humerus c. Teres minor, inserts on the greater tubercle of humerus 1 vii. Circumflexion a. Pectoralis major, inserts on the greater tubercle and lateral lip of intertubercular sulcus of humerus b. Deltoid (anterior, lateral and posterior fibers), inserts on the deltoid tuberosity of humerus c. Supraspinatus, inserts on the lesser tubercle of humerus d. Triceps (long head), inserts on olecranon process of ulna e. Biceps brachii, insert on radial tuberosity of radius and bicipital aponeurosis 2. What are EPSPs and IPSPs, and how are they produced? Explain how these electrical currents are used in spatial and temporal summation to initiate or inhibit the generation of an action potential. ESPSs – Excitatory postsynaptic potential cause the depolarization of a postsynaptic membrane. This is excitatory due to the ESPSs ability to being the membrane of the postsynaptic neuron closer to the threshold, the membrane becomes more positive. Although a single ESPS does not initiate a nerve impulse, the postsynaptic cell does become more excitable, being it is partially depolarized, and is more likely to reach threshold when the next EPSP occurs. IPSPs – Inhibitory postsynaptic potential cause the hyperpolarization of the postsynaptic membrane. It is inhibitory because the generation of an action potential becomes more difficult because the membrane potential becomes more negative, further away from the threshold than in resting potential. Production of ESPSs and IPSPs: Neurotransmitters released from the presynaptic neuron bind to the neurotransmitter receptors in the plasma membrane of a postsynaptic cell. Many excitatory neurotransmitters bind to ionotropic receptors that contains cation channels. Ionotropic receptors are a type of neurotransmitter receptor that contains a neurotransmitter-binding site and an ion channel. EPSPs results from opening these cation channels. When cation channels open, they allow passage of the three cations (Na+, K+, Ca2+) through the postsynaptic cell membrane, but Na+ inflow is greater than either Ca2+ inflow K+ outflow and the inside of the postsynaptic cell becomes less negative (depolarized). Many inhibitory neurotransmitters also bind to ionotropic receptors that contain chloride channels. When Cl- channels open, a larger number of chloride ions diffuse inwards. The inward flow of chloride ions causes the inside of the postsynaptic cell to become more negative (hyperpolarized). Whereas, metabotropic receptors differ from ionotropic because they do not contain ion channels but instead communicate by activating another molecule though G proteins that open or close an ion channel. Spatial and Temporal Summation: Summation of postsynaptic potentials that form in the postsynaptic neuron is the process by which ESPSs and IPSPs generate their electrical currents by adding their graded potentials together, after which an action potential is excited or inhibited. There are two types of summation that can occur: spatial or temporal. Spatial summation of postsynaptic potentials is in response to stimuli that occur at different locations at the same time. For example, spatial summation results from the buildup of neurotransmitters released simultaneously by several presynaptic end bulbs. Temporal summation of postsynaptic potentials in response to stimuli that occur at the same location at different times. This will occur from the buildup of neurotransmitter released by a single presynaptic end bulb two or more times in rapid succession. A typical ESPS lasts about 15 milliseconds, the second and subsequent release of neurotransmitters must occur soon after the first one is temporal summation is to occur. A single postsynaptic neuron receives input from many presynaptic neurons, some of which release excitatory neurotransmitters and some of which release inhibitory neurotransmitters. • EPSP: if the total excitatory effects are greater than the total inhibitory effects but less than the threshold level of stimulation, the result is an EPSP that does not reach threshold. Following an EPSP, subsequent stimuli can more easily generate a nerve impulse through summation because the neuron is partially depolarized. [Show More]

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