Notes, summaries, assignments, exams, and problems for Biology

Digestive Phases

Cephalic Phase

The cephalic phase initiates digestion before food even reaches the stomach. Sensory cues like taste, smell, or even the thought of food trigger the central nervous system to stimulate gastric juice production.

Gastric Phase

Once food enters the stomach, receptors signal the brain, which in turn promotes further gastric juice secretion to break down the ingested food.

Intestinal Phase

As food moves into the duodenum, receptors detect its presence and signal the brain to increase the production of digestive juices for further processing.

Enterogastric Reflex

When the duodenum is full, the enterogastric reflex is activated, causing the pyloric sphincter to close and regulate the passage of chyme from the stomach to the... Continue reading "Digestive System Processes: A Comprehensive Guide" »

Lower First Premolar

Prominent Elevations & Depressions/Snake-Snail Eye Lingually

Chronology

• Enamel: 5-6 years old
• Eruption: 10-11 years old
• Root: 12-13 years old

Geometry

• Lingual/Buccal: Trapezoid; short side cervical
• Mesio-Distal: Rhomboidal
• Occlusal: Diamond

Buccally

• Cervical Ridge
• Buccal Ridge
• Mesio-Distal Buccal Developmental Groove

Lingually

• Mesio-lingual Developmental Groove

Mesially

• Mesio-lingual Developmental Groove

Mesial Contact Area

• Junction between buccal and middle thirds

Distal Contact Area

• Middle third

Occlusally

• 2 well-developed cusps
• Each cusp: triangular ridge
• Mesial/Distal Marginal Ridges
• Triangular Fossae
• Developmental Pits
• Central Developmental Groove
• Transverse Ridge
• Mesio-lingual Developmental Groove

Lower Second Premolar

3-Cusp Type has 5 Lobes

ACTIVITIES

Trasplant: is a surgical procedure in which diseased or injured organs, tissues, cells are replaced with healthy one from a donor.

|The donor can be another person, the same person or an animal|

Types of transplant:

-Autotrasplant: the recipient and donor are the same person

-Allogeneic transplant:  the donor is another person

-Xenotrasplant: the donor is an animal

Organ donation: is voluntary. Donors must be in good health, free from mental health problems, of legal age, not receive money in exchange for their organs, and give written consent

Types of donation:

-Cells:... Continue reading "A body is placed in a certain airstream" »

The Skeletal System: The Internal Framework of the Body

The skeletal system is the internal framework (structure) of the body. It is made up of 206 bones and tissue.

Support

Bones hold our body and give us shape. For example, the spinal cord provides support.

Protection

The skeleton protects our vital organs. For instance, the skull protects the brain, and the ribs protect our heart and lungs.

Movement

Bones allow us to move as a whole body or as individual parts.

Blood Production

Certain bones in the skeleton contain red bone marrow, which produces red blood cells, white blood cells, and platelets.

Storage

Our bones can store different minerals, such as calcium.

Endocrine Regulation

Endocrine glands produce hormones, and the skeletal system helps regulate... Continue reading "The Importance of the Skeletal System in the Human Body" »

The Human Eye

Structure and Function

The Retina

The retina is a structure at the back of the eye that contains light-sensitive cells called rods and cones.

• Rods: Detect different light intensities, see in black and white, sensitive to low light levels, used to see in dim light.
• Cones: Different types sensitive to different colors (especially primary colors), need bright light to work, cannot see in dim light.

The central part of the retina has a lot of cone cells and no rod cells. The outer part of the retina has no cone cells and a lot of rod cells.

Blind Spot

The blind spot is the point where the optic nerve leaves the eye. There are no receptor cells in this area.

Cornea

The cornea is the transparent front part of the eye. It protects the eye and... Continue reading "The Human Eye: Structure, Function, and Vision" »

The Nervous System

The nervous system receives information from the receptors, processes and coordinates it, and generates orders to the effectors.

Central Nervous System (CNS)

The central nervous system coordinates all the body's functions. It is formed by the encephalon and the spinal cord.

The Encephalon

The encephalon is protected by the skull or cranium and by three membranes, the meninges, between which a liquid called the cerebrospinal fluid circulates. This liquid protects the encephalon from knocks and blows. The encephalon is divided into three parts: the brain, the cerebellum, and the brainstem.

• The brain is divided into two hemispheres, separated by a fissure. Its surface, called the cerebral cortex, is rough and full of folds and furrows,

Water: Properties and Cycle

Properties of Water

Freshwater: Salinity below 35g/L.

Saltwater (Ocean Water): Salinity over 35g/L.

General Properties: Colorless, odorless, tasteless. Higher density in liquid state than solid state. Universal solvent. High heat capacity. Facilitates many chemical reactions. Exhibits adhesive capacity.

States of Water

• Solid (S)
• Liquid (L)
• Gas (G)

Transitions: S --(fusion)--> L --(vaporization)--> G --(condensation)--> L --(solidification)--> S S --(sublimation)--> G --(inverse sublimation)--> S

Water as a Thermal Regulator

Water's high heat capacity means significant temperature changes require large amounts of energy. This explains why coastal regions experience milder climates compared to inland areas.

The

-Antigen:Molecule that the immune system identifies as foreign and responds to by forming antibodies.

The Discovery of Cells

a) In 1655, scientist Robert Hooke made an observation while examining a dried section of cork tree with a crude light microscope. He observed small chambers and named them "cells."

What are Cells?

b) The cell is known as the basic structural and functional unit of life, as all organisms are composed of cells.

c) Single-celled organisms are called unicellular (e.g., amoeba), while those having more than one cell are called multicellular.

Functions of Cells

d) All basic chemical and physiological functions of living beings - for example, repair, growth, movement, immunity, communication, and digestion - are carried out inside the cells.

Structure of a Cell

e) Cells are mostly round, spherical, or elongated. Some cells are quite... Continue reading "Exploring the Building Blocks of Life: An Introduction to Cells" »