💎 The three major salivary glands are:

1. Parotid glands – located in the cheeks, just in front of the ears.
2. Sublingual glands – found under the tongue.
3. Submandibular glands – located beneath the jawbone (mandible).

💎 These glands produce saliva that aids in digestion, lubrication, and oral hygiene.

💎Each gland contributes to the overall volume and enzyme content of saliva, particularly amylase for starch breakdown.

✓ Renin is an enzyme secreted by the kidneys in response to low blood pressure, low sodium levels, or sympathetic nervous stimulation.

✓ It plays a key role in the renin-angiotensin-aldosterone system (RAAS), which helps regulate blood volume and systemic blood pressure.

✓ Renin converts angiotensinogen (from the liver) into angiotensin I, which is then converted into angiotensin II, a potent vasoconstrictor that increases blood pressure and stimulates aldosterone release for sodium and water retention.

✓ "m" stands for meters, the SI (International System of Units) unit for length.

✓ It is used to measure distances or the size of objects, from microscopic levels to astronomical scales.

✓ Other units listed are for different measurements:

1. kg = kilograms (mass)
2. L = liters (volume)
3. s = seconds (time)

◈ The researcher is specifically collecting quantitative data on the number of cars passing through an intersection at different times of day.

◈ This information is directly suited for analyzing traffic patterns, especially to identify peak congestion times or rush hour trends.

◈ While vehicle count may indirectly relate to air or noise pollution, it does not directly measure those variables.

◈ The focus and most useful application of this data is in traffic flow analysis.

💧 The chemical formula for water is H₂O, indicating that each molecule contains two hydrogen atoms and one oxygen atom.

💧 These atoms are bonded through polar covalent bonds, creating a molecule with unique properties like high surface tension, cohesion, adhesion, and a high specific heat, all essential for life.

🍃 The skin is the largest organ in the human body by surface area and weight, covering approximately 1.5 to 2 square meters in adults and weighing around 3.6 kilograms (8 pounds).

🍃 It is part of the integumentary system and serves vital functions such as protection, temperature regulation, sensory perception, and vitamin D synthesis.

🍃 Its layered structure (epidermis, dermis, and hypodermis) allows it to act as a barrier against pathogens and environmental damage.

💎 Ligaments are strong, fibrous connective tissues that connect one bone to another at joints, providing stability and support.

💎 They help guide joint movement and prevent excessive motion, reducing the risk of injury.

💎 Ligaments are especially important in joints such as the knee, elbow, and shoulder, where complex motion occurs.

💎 In contrast, tendons connect muscles to bones, allowing movement when muscles contract.

✳️ Transfer RNA (tRNA) is the molecule responsible for carrying specific amino acids to the ribosome during translation, the second phase of protein synthesis.

✳️ Each tRNA has an anticodon that pairs with a complementary codon on the mRNA strand, ensuring the correct amino acid is added to the growing polypeptide chain.

✳️ This process takes place in the cytoplasm and is essential for building proteins according to the genetic code.

💎 The diaphragm is a dome-shaped muscle located at the base of the lungs, and it plays a central role in controlling the rate and depth of breathing.

💎 When the diaphragm contracts, it flattens and increases the volume of the thoracic cavity, causing inhalation. When it relaxes, it decreases the volume, leading to exhalation.

💎 Breathing rate and depth are also regulated by the brainstem (medulla oblongata and pons), which sends signals to the diaphragm in response to CO₂ levels in the blood.

💎 Thus, while the brain regulates the signals, the diaphragm physically carries out the adjustments in breathing.

🔹 Transcription is the process by which a segment of DNA is used as a template to synthesize RNA, specifically messenger RNA (mRNA).

🔹 This occurs in the nucleus of eukaryotic cells and is the first step in gene expression.

🔹 The mRNA strand then exits the nucleus and is used during translation to build a protein.

🔹 Replication copies DNA into DNA, translation builds proteins from RNA, and mutation refers to changes in the DNA sequence.