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

Homeostasis and Environmental Response

All living things interact with their environment, including their surroundings and other organisms.

The environment is constantly changing. To survive and reproduce, living organisms must detect these changes and respond appropriately.

Responding to Stimuli

1. A stimulus is detected by receptors (structures or organs).
2. The stimulus is relayed to coordination systems, which interpret the signal and produce a response.
3. The organism responds using effectors (organs or structures).

Maintaining Internal Balance

To survive, living organisms must regulate their internal conditions.

Examples of internal conditions include temperature, water content, and concentrations of mineral salts and glucose in the blood.

Changes in... Continue reading "Homeostasis and Stimuli in Living Organisms" »

Blood: Composition and Vital Functions

Blood Composition

• Blood Plasma: The liquid component of blood.
• Blood Cells:
  • Red Blood Cells (Erythrocytes): Primarily responsible for oxygen transport.
  • White Blood Cells (Leukocytes): Key components of the body's immune and defense system.
  • Platelets: Essential for blood clotting and preventing excessive bleeding.

Key Functions of Blood

Blood serves as an effective transport system for various substances throughout the body:

• Oxygen Transport: Carries oxygen gas, primarily bound to hemoglobin. When hemoglobin is highly saturated with oxygen, it is called oxyhemoglobin.
• Nutrient and Waste Transport: Moves nutrients to cells and carries metabolic waste products away for excretion.
• Heat Distribution: Helps regulate and

Heart Anatomy and Function

Chambers and Valves

The heart is a muscular, hollow organ divided into four chambers:

• Upper Chambers (Atria): Left atrium and right atrium.
• Lower Chambers (Ventricles): Left ventricle and right ventricle.

Between the atrium and ventricle, the atrioventricular valve allows blood flow from the atrium to the ventricle but prevents backflow. The valve between the left atrium and ventricle is bicuspid, while the valve between the right atrium and ventricle is tricuspid.

Blood Circulation

Cardiac Cycle

• Atrial Systole: Atria contract, pumping blood into the ventricles through open atrioventricular valves.
• Ventricular Systole: Ventricles contract, sigmoid valves open, and blood flows into the pulmonary artery and aorta. Atrioventricular

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Endocrine Functions § Pancreatic islets § Secrete hormones insulin and glucagon into blood Exocrine functions § Secretes pancreatic juice into duodenum § Alkaline fluid introduced with enzymes neutralizes chyme from stomach Pancreatic Juice

• Water, bicarbonate solution, enzymes
• Bicarbonate solution: neutralizes gastric HCL & shift pH of duodenum to 8
• Enzymes: § Pancreatic amylase: digests salts § Trypsinogen - digests proteins § Lipase - digests triglycerides

Agriculture:

Deliberate land modification through plant cultivation and raising animals for food or profit Dominant economic activity Requires physical and demographic contributions in regions

Hemoglobin:

Globin combined with 4 iron atoms • 280 million molecules... Continue reading "Endocrine Functions of the Pancreas and Other Organ Systems" »

Menstrual Cycle

Pre-menstrual phase: the lining of the uterus begins to break down, progesterone decreases. Menstruation: the endometrium is detached, loss of blood and it is caused by progesterone. Usually it lasts 4 days. Repair phase: the lining of the uterus starts to thicken and becomes more stable. Increase in the concentration of estrogen. Ovulation: occurs around day 14, the ovum is released, there is a peak of estrogen and they are the most fertilized days. Receptive phase: the lining of the uterus is well developed if the ovum has been fertilized it implants itself in the tissue. Hormones: FSH: stimulates the follicle (brain) LH: produces ovulation (brain). Estrogen: creates new endometrium (ovary). Progesterone: makes the endometrium... Continue reading "Understanding the Menstrual Cycle, Pregnancy, and Reproduction" »

Chapter 7 (Sections 1, 2, and 3)

Nutrition: The Science or Study of Food and the Ways in Which the Body Uses Food

Nutrients: Substances in Food that Provide Energy or Help Form Body Tissues and Are Necessary for Life and Growth

Carbohydrates: Class of Energy-Giving Nutrients that Includes Sugar, Starches, Fiber, and Glycogen

Fats: Class of Energy-Giving Nutrients and Are the Main Form in Which Energy Is Stored in the Body

Proteins: Class of Energy-Giving Nutrients Made Up of Amino Acids Which Are Needed to Build and Repair Body Structures and to Regulate Processes in the Body

Glycogen: Made in the Body Which Is Made of Many Glucose Units Linked Together Stored in the Muscle and Liver of Human and Animals Can Be Broken Down to Provide a Quick Source

• In the case of partial injuries, some sensation and movement may be retained below the level of the injury.

• In complete injuries, there is a loss of sensation and total muscular paralysis below the level of the injury

• Depression is a mental illness that often takes the form of low mood and an inability to lead a normal life

Essential Nutrients: A Comprehensive Guide

1. Six Classes of Nutrients

• Carbohydrates (provide energy)
• Fats (provide energy)
• Proteins (provide energy)
• Vitamins (do not provide energy)
• Minerals (do not provide energy)
• Water (does not provide energy)

2. Functions of Carbohydrates, Proteins, and Fats

Carbohydrates

Carbohydrates are broken down into glucose, which is the body's main source of energy. They are important for the brain, nervous system, kidneys, and muscles. Carbohydrates are stored in the liver and muscles for later use as energy. Fiber, a type of carbohydrate, promotes bowel health by allowing waste to move more quickly through the gut. Carbohydrates are found in grains, fruits, milk, nuts, seeds, beans, and vegetables.

Proteins

Proteins build... Continue reading "Essential Nutrients: A Comprehensive Guide to Macronutrients, Micronutrients, and Their Functions" »

Essential Biological Definitions: Blood, Systems, and Pathology

Blood Components and Characteristics

Chordae Tendineae: "Heart Strings"

These are fibrous cords that connect the papillary muscles to the cusps of the atrioventricular valves (mitral and tricuspid valves) in the heart.

Erythrocytes (Red Blood Cells)

The primary function of erythrocytes is oxygen transport.

Leukocytes (White Blood Cells)

Leukocytes are crucial components of the immune system, defending the body against infection and disease.

Granulocytes

Their cytoskeleton contains visible granules.

Agranulocytes

The cytoskeleton lacks granules. There are two main kinds:

• Lymphocytes: Possess large spherical nuclei.
  • T Lymphocytes: Found primarily in the lymph; they attack tumor cells.
  • B Lymphocytes:

Components of the Alpha-Ketoglutarate Dehydrogenase Reaction

1. CoA (Coenzyme A)
2. NAD⁺
3. α-Ketoglutarate Dehydrogenase Complex
4. NADH + H⁺
5. CO₂
6. α-Ketoglutarate
7. Succinyl CoA

Identifying the Reaction

The following components are involved in the reaction catalyzed by Citrate Synthase:

1. Oxaloacetate
2. Citrate
3. Acetyl CoA
4. Citrate Synthase (Enzyme)

The Acetyl Radical of Acetyl-CoA

What is the role of the acetyl radical of Acetyl-CoA?

The Role of Acetyl CoA in the Krebs Cycle

Acetyl CoA is essential for the Krebs cycle (Tricarboxylic Acid Cycle) to occur. It reacts with Oxaloacetate to start the cycle.

During the cycle, 2 CO₂ and 3 NADH + H⁺ are produced (per Acetyl CoA molecule entering the cycle). Specifically, the production of NADH and CO₂ occurs:

• 1 CO₂ and 1 NADH + H⁺ are