Physiology Practical Report 2022

Running head: PHYSIOLOGY PRACTICAL REPORT
Title
Name of the Student
Name of the University
Author’s Note

1
PHYSIOLOGY PRACTICAL REPORT
1 A. Skeletal movements are based on proper contraction of muscle followed by its
relaxation. The skeletal muscles are made of muscle fibers which are composed of
sarcomeres, the main functional units of skeletal muscles. These sarcomeres
contain several overlapping parallel thin units known as actin filaments and thick
overlapping parallel units known as myosin filaments. The sliding of these filaments
on each other leading to the reduction of the sarcomere length results in muscle
contraction (Lau et al. 2015). This movement causing muscle contraction is called
cross-bridge cycling (Matusovsky, Mayans and Szczesna-Cordary 2015). The cross-
bridge cycling consists of four vital steps.
a. First is the nervous activation of the skeletal muscle, thereby releasing the
neurotransmitter.
b. Secondly, this neurotransmitter increases the calcium concentration around
the actin and myosin filaments.
c. Thirdly, this increased calcium promotes the muscle contraction.
d. Finally, when the nerve stimulus is removed, the calcium level reduces, thus
ending the muscle contraction
1 B. The molecular basis of muscle contraction lies in the sarcomeric cross bridge
contraction cycling (Matusovsky, Mayans and Szczesna-Cordary 2015).
 Nerve stimulation releases neurotransmitter which triggers the muscular
contraction and this neurotransmitter increase the calcium concentration
around the actin and myosin filaments.
 Actin myofilaments consist of troponin, which are bound by this calcium. This
binding of calcium with the troponin, causes displacement of tropomyosin,
placed along myofilaments.
 This displacement leads to the exposure of the binding sites on the myosin
filaments, which at that point of time is bound to ADP molecule and a
remaining phosphate molecule from prior contraction.
 Now, post displacement of the tropomyosin, the myosin discharges the
remaining phosphate and the exposed myosin binds with the actin, via the
recently uncovered myosin binding spots, forming a crosslink between the two
myofilaments.

2
PHYSIOLOGY PRACTICAL REPORT
 The gliding movement, past the two myofilaments is propelled by the
movement which is head-first basic and this movement is power driven by the
ATPs stored in the myosin heads.
 As the movement progresses, ATP is utilized to form ADP. These generated
ADP molecules then bind to the myosin heads and disconnects the crosslink
between the actin and the myosin. Now, the filaments are ready for new
muscular contraction.
2 A. Hypothesis for the work conducted in experiment one:
H1: The muscle force output based on grip is more in male as the males have
greater higher forearm diameter as compared to females.
H0: The muscle force output based on grip is not more in male as the males have
same forearm diameter as compared to females.
2 B. Aim of the experiment two is to test the effect of Drug X, which is a calcium
channel inhibitor on cardiac myocyte and calculate the contractile force thereby
determining the force output.
3 A. In experiment one, the column consisting of the age of the participants may be
excluded
In experiment two, the column highlighting the electrical stimulation may be excluded
3B. In the first experiment, the age of the participants in this excel does not add any
extra information regarding the forearm size on muscle force output attributed by the
grip force. Ages included in the study are all adults from the age of 19 to age 57 and
muscle force output does not alter much over this age span. Change of muscle
output might be noted in children and old seniors.
In experiment two, the electrical stimulation data is not consistently present for every
concentration of Drug X used, thus making the column redundant. In addition,
electrical stimulation is always required for triggering a nerve impulse which leads to