PHATFIT

Mr. Edjel Fabian

Cardiovascular Anatomy
The human heart is a complex muscular organ that plays a central role in the circulatory system,
facilitating the flow of blood throughout the body. Its anatomy, the associated blood vessels, and
the pathway of blood flow are essential for maintaining homeostasis.
The anatomy of the human heart, with its four chambers, valves, and associated blood vessels, is
intricately designed to facilitate the efficient circulation of blood. This structure is essential for
delivering oxygen and nutrients to tissues, removing waste products, and supporting overall
physiological functions.
Blood from the body returns to the right atrium through two large veins: the superior vena cava
(which drains blood from the upper body) and the inferior vena cava (which drains blood from the
lower body).When the right atrium fills, it contracts, pushing blood through the tricuspid valve
into the right ventricle.The right ventricle then contracts, sending blood through the pulmonary
valve into the pulmonary arteries. These arteries carry the deoxygenated blood to the lungs.In the
lungs, blood travels through tiny capillaries surrounding the alveoli, where carbon dioxide is
exchanged for oxygen. This oxygenation process is crucial for replenishing the blood's oxygen
content.The newly oxygen-rich blood returns to the left atrium via the pulmonary veins (two from
each lung).As the left atrium fills, it contracts, pushing blood through the mitral valve into the left
ventricle.The left ventricle contracts powerfully, propelling the oxygenated blood through the
aortic valve into the aorta, the largest artery in the body. From here, blood is distributed to the
rest of the body through various arteries.
The circulatory system ensures that oxygen is efficiently delivered to tissues throughout the
body, which is vital for cellular respiration and energy production. Blood carries essential
nutrients (like glucose, amino acids, and vitamins) from the digestive system to cells, facilitating
growth, repair, and overall function.Blood transports metabolic wastes (such as carbon dioxide
and urea) to the lungs and kidneys for elimination, preventing toxicity and maintaining pH
balance. Blood flow helps regulate body temperature by redistributing heat. Vasodilation
(widening of blood vessels) allows for heat loss, while vasoconstriction (narrowing) helps retain
heat. The circulatory system transports hormones from endocrine glands to target organs,
regulating various physiological processes and maintaining homeostasis. · Blood carries white
blood cells and antibodies throughout the body, enabling a rapid immune response to infections
and injuries. The circulatory system works alongside the lymphatic system to maintain fluid
balance, preventing edema and ensuring proper hydration of tissues.
The pathway of blood flow through the heart is integral to the body’s ability to maintain
homeostasis. By ensuring that oxygen, nutrients, and hormones are delivered to cells, while
efficiently removing waste products, this circulatory system supports the overall health and
stability of the organism. Any disruption in this pathway can lead to significant health issues,
highlighting the importance of a well-functioning cardiovascular system in maintaining balance
within the body.

Romili B. Macapas
DHMT-1
 PHATFIT
Mr. Edjel Fabian
Respiratory System Mechanics
The lungs, diaphragm, and associated airways are essential components of the human
respiratory system. Together, they facilitate the intake of oxygen and the removal of carbon
dioxide, ensuring that the body’s cells receive the necessary gases for metabolism and function.
This intricate system works continuously to maintain respiratory efficiency and overall
homeostasis.

The lungs are two large, spongy organs located in the thoracic cavity, protected by the rib
cage.
The right lung has three lobes (upper, middle, lower), while the left lung has two lobes (upper and
lower) to accommodate the heart.Each lung is surrounded by a double-layered pleural membrane
(pleura) that provides lubrication and reduces friction during breathing.The primary function of
the lungs is to facilitate gas exchange. Oxygen is absorbed into the bloodstream, while carbon
dioxide is expelled.At the end of the bronchioles are tiny air sacs called alveoli. Each lung
contains millions of alveoli, which provide a large surface area for gas exchange.Alveoli are
surrounded by a network of capillaries, allowing for efficient diffusion of oxygen into the blood
and carbon dioxide out of the blood.

The diaphragm is a dome-shaped muscle located at the base of the thoracic cavity,
separating it from the abdominal cavity.It is composed of skeletal muscle and connective
tissue.The diaphragm plays a crucial role in respiration. During inhalation, the diaphragm
contracts and flattens, increasing the volume of the thoracic cavity and drawing air into the
lungs.During exhalation, the diaphragm relaxes, returning to its dome shape, which decreases the
thoracic cavity volume and pushes air out of the lungs.

Nasal Cavity Air enters the respiratory system through the nostrils into the nasal cavity,
where it is filtered, warmed, and humidified.
Pharynx, The air then passes into the pharynx, a shared passage for air and food, which directs
air to the larynx.
Larynx, Also known as the voice box, the larynx contains the vocal cords and is
responsible for sound production. The epiglottis prevents food from entering the airway during
swallowing.
Trachea, The trachea, or windpipe, extends from the larynx and divides into the primary
bronchi. It is reinforced with C-shaped cartilage rings to keep it open.
Bronchi and Bronchioles, The trachea bifurcates into the right and left primary bronchi,
which lead to each lung. The bronchi branch into smaller bronchi and eventually into bronchioles,
which end in alveolar sacs.The walls of the bronchi and bronchioles contain smooth muscle and
mucous glands, helping regulate airflow and trap particles.
Romili B. Macapas
DHMT-1
 PHATFIT
Mr. Edjel Fabian
Muscle Physiology
Muscle contraction is a complex process that involves the interaction between two key
protein filaments: actin and myosin. This process is fundamental to muscle movement and occurs
through a mechanism known as the sliding filament theory.
Muscle Cells (Myocytes) Muscle fibers, or myocytes, contain myofibrils, which are long,
thread-like structures that run parallel to the length of the fiber. Myofibrils are composed of
repeating units called sarcomeres, the basic functional units of muscle contraction.
Actin is thin filaments made primarily of the protein actin. Each actin filament is a helical
structure that contains binding sites for myosin.
Myosin is thick filaments made of myosin protein, which has a head that can bind to actin.
Myosin heads have ATPase activity, allowing them to hydrolyze ATP to generate energy for
contraction.
Mechanism of Muscle Contraction
Neuromuscular Junction Activation is Muscle contraction begins with an action potential
(nerve impulse) that reaches the neuromuscular junction, where a motor neuron communicates
with a muscle fiber. The release of neurotransmitter (acetylcholine) from the motor neuron
stimulates the muscle fiber, leading to depolarization and the generation of an action potential in
the muscle cell.
Calcium Release is the action potential travels along the sarcolemma (muscle cell
membrane) and into the T-tubules, triggering the release of calcium ions (Ca²⁺) from the
sarcoplasmic reticulum (SR), a specialized organelle that stores calcium.
Relaxation of Muscle is when the nerve stimulation ceases, calcium ions are pumped back
into the sarcoplasmic reticulum, reducing calcium levels in the cytoplasm. As calcium dissociates
from troponin, tropomyosin shifts back to block the binding sites on actin, preventing further
interaction with myosin. The muscle fiber relaxes as the actin and myosin filaments slide back to
their original positions.
Neuromuscular junctions (NMJs) play a crucial role in facilitating muscle contraction by
serving as the interface between motor neurons and muscle fibers.
Role of Neuromuscular Junctions
Structure of NMJ consists of a motor neuron terminal and the muscle fiber's
postsynaptic membrane (sarcolemma).The synaptic cleft separates these two structures, allowing
for neurotransmitter release and action.
Action Potential Propagation, When a motor neuron is stimulated, an action potential
travels down the neuron to the NMJ. This depolarization opens voltage-gated calcium channels in
the neuron, allowing calcium ions (Ca²⁺) to enter.
Neurotransmitter Release the influx of calcium triggers the release of acetylcholine (ACh)
from synaptic vesicles in the neuron into the synaptic cleft. ACh binds to nicotinic receptors on
the muscle fiber’s sarcolemma, leading to depolarization of the muscle membrane.

Romili B. Macapas
DHMT-1
 PHATFIT
Mr. Edjel Fabian

Muscle Fiber Activation is the binding of ACh generates an action potential in the muscle
fiber, which spreads along the sarcolemma and into the T-tubules.This depolarization leads to the
release of calcium ions from the sarcoplasmic reticulum, initiating the process of muscle
contraction.
Termination of Signal is the action of ACh is terminated by the enzyme
acetylcholinesterase, which breaks down ACh in the synaptic cleft. This prevents continuous
stimulation of the muscle fiber and allows for relaxation.

Physiological Factors Affecting Muscle Performance

Nerve Stimulation is he frequency and intensity of motor neuron firing influence muscle
contraction strength and duration. Higher frequencies can lead to tetanus, where muscle fibers do
not relax fully, resulting in sustained contraction.
Muscle Fiber Type Muscle fibers can be classified into
Type I (slow-twitch): More resistant to fatigue, suited for endurance activities.
Type II (fast-twitch): Generate more force but fatigue more quickly, suited for short bursts of
activity. The composition of muscle fibers affects overall muscle performance.
Calcium Availability is Adequate calcium levels in the sarcoplasm are essential for muscle
contraction. Disruptions in calcium signaling can impair contraction strength.
ATP Availability, ATP is required for both the power stroke of myosin heads and for the
reuptake of calcium into the sarcoplasmic reticulum during relaxation. Insufficient ATP can lead
to fatigue.

Neuromuscular junctions are critical for initiating muscle contraction by facilitating

communication between motor neurons and muscle fibers. Various physiological factors,
including nerve stimulation, muscle fiber types, calcium and ATP availability, pH levels,
temperature, nutrition, and hormonal influences, collectively affect muscle performance.
Understanding these elements is essential for optimizing muscle function and improving athletic
performance.

Romili B. Macapas
DHMT-1
 PHATFIT
Mr. Edjel Fabian

Endocrine System Functions

Endocrine glands coordinate various physiological processes through hormone secretion,

regulating metabolism, growth, reproduction, and overall homeostasis. Understanding their
functions is essential for grasping how the endocrine system affects health and wellness.
Hypothalamus it regulates the pituitary gland and various bodily functions such as temperature,
hunger, thirst, and circadian rhythms. Pituitary Gland referred to as the "master gland," it
controls other endocrine glands. Thyroid Gland it regulates metabolism, growth, and
development. Parathyroid Glands it regulate calcium levels in the blood. Adrenal Glands it
produce hormones for stress response and metabolism. Pancreas it regulates blood glucose levels.
Gonads it produce sex hormones and regulate reproductive functions. Pineal Gland it regulates
sleep-wake cycles.

Hormones produced by the major endocrine glands play critical roles in regulating
various physiological processes throughout the body. Hormones produced by the endocrine glands
regulate a wide range of physiological processes, from metabolism to reproduction. Hormonal
imbalances can have significant consequences on health, leading to various disorders that affect
overall well-being. Proper hormonal function is essential for maintaining homeostasis, and
understanding these relationships helps in diagnosing and managing endocrine disorders
effectively.

Hormonal imbalances can significantly affect overall health, leading to various physical
and mental health issues. Early detection and management are crucial for restoring balance and
preventing complications

Romili B. Macapas
DHMT-1