Notes, summaries, assignments, exams, and exercises for Biology for Baccalaureate

Fundamental Properties of Muscle Tissue

Muscles possess unique characteristics that allow them to function effectively within the body:

• Excitability: They can receive and respond to stimulation from the brain.
• Contractility: They can contract (shorten) following stimulation.
• Extensibility: They can expand (stretch) through the application of force.
• Elasticity: They return to their original shape and length after being contracted or extended.

Structural Hierarchy of Skeletal Muscle

The connection from bone to the functional unit of the muscle follows a specific hierarchy:

Bones → Muscles (via Tendons) → Fascicle → Muscle Fiber → Myofibrils (containing Sarcomeres)

Neural Control of the Knee-Jerk Reflex

During a reflex action, such as a knee tap,...

Cell Structure and Membrane Transport

9) Which component is a microfilament (actin filament) of the cytoskeleton?

C

10) Which component is a glycolipid?

B

11) Which of the following most accurately describes selective permeability?

Only certain molecules can cross a cell membrane.

12) Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?

CO2

13) Which of the following allows water to move much faster across cell membranes?

Aquaporins

14) Diffusion _____.

Is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.

15) Which of the following is true of osmosis?

In osmosis, water moves across a membrane from areas of lower solute concentration to areas

Applications of Proteins

Rubisco

• Catalyzes the CO₂ fixation reaction in the Calvin cycle.
• Full name: ribulose bisphosphate carboxylase.
• One of the most abundant and important enzymes.

Insulin

• Hormone produced by pancreatic beta cells.
• Reduces blood glucose levels by promoting glucose absorption.
• Binds reversibly to cell membrane receptors.

Immunoglobulins (Antibodies)

• Y-shaped proteins produced by plasma B cells.
• Identify and neutralize foreign pathogens.
• Act as markers for pathogen destruction by phagocytes.
• Each antibody is specific to a particular pathogen.

Rhodopsin

• Biological pigment in retinal photoreceptor cells.
• Consists of a retinal molecule surrounded by an opsin polypeptide.
• Light absorption changes its shape, sending a nerve impulse to the brain.

Cardiovascular System: Key Definitions

Cardiovascular Disease

It can be caused by smoking, poor diet, stress, physical inactivity, or hereditary factors.

Atherosclerosis

It is the hardening of artery walls caused by the buildup of cholesterol and lipids.

Hypertension

It is abnormally high blood pressure.

Heart Attack

It occurs when an artery that supplies blood to the heart becomes blocked.

Stroke

It occurs when a blood vessel in the brain becomes blocked or bursts.

Respiratory System Anatomy

The main parts of the respiratory system include:

• Nasal Cavities
• Mouth
• Pharynx
• Larynx
• Trachea (Windpipe)
• Bronchus
• Bronchiole
• Alveoli
• Lungs
• Diaphragm

Respiratory System Part Identification

1. It is the organ that produces the sense of smell: Nose/Nasal Cavity
2. It is also known as the

Challenges in Cartilage Repair

Chondral defects represent a challenging clinical problem, aggravated by the increase in the elderly population in developed countries. Consequently, many strategies—including arthroplasty, the stimulation of reparative tissues through arthroscopic abrasion, drilling, or microfracture¹—have been developed to treat injured cartilage. However, these procedures cannot successfully reproduce the tissue characteristics of hyaline cartilage^{2, 3}.

New biologically based strategies, such as the replacement of damaged surfaces with healthy tissue (osteochondral grafts)⁴ or the implantation of cultured expanded autologous chondrocytes, have been used for cartilage repair⁵. Nevertheless, the difficulty in obtaining sufficient...

Diffusion

Diffusion is the net movement of molecules from a region of high concentration to a region of low concentration. This is a passive cell movement, meaning cells do not need to use energy for it.

Concentration Gradient

The concentration gradient is the difference in the concentration of molecules between two places.

Factors Affecting Diffusion

• Distance molecules travel (shorter distances enhance diffusion)

• Concentration gradient (a steeper gradient increases the rate)

• Surface area (larger areas facilitate more diffusion)

• Temperature (higher temperatures increase kinetic energy, speeding up diffusion)

• Size of molecule (smaller molecules diffuse more rapidly)

Osmosis

Osmosis is a special type of diffusion, specifically the passage of water molecules...

The Cardiac Cycle

The heartbeat is the movement that pumps blood through the body. It consists of two primary states:

• Systole: Coordinated rhythmic contraction.
• Diastole: Relaxation involving all four chambers of the heart.

Phases of the Cardiac Cycle

1. Atrial Systole: Both atria contract, mitral and tricuspid valves open, and both ventricles fill.
2. Ventricular Systole: Both ventricles contract, semilunar valves open, and blood is pushed through the aorta and pulmonary artery while mitral and tricuspid valves close.
3. Diastole: Atria and ventricles relax, semilunar valves close, and ventricles fill with blood.

The Double Circulatory System

This system keeps oxygenated and deoxygenated blood separate:

• Pulmonary Circuit: Pumps blood between the heart and lungs

Essential Nutrients

Carbohydrates, proteins, and lipids are needed in significant amounts, while vitamins, minerals, and water are also crucial. Most foods are concentrated sources of one or two nutrients.

Food Groups

Foods are typically classified into five main groups:

• Grains
• Vegetables
• Fruits
• Milk
• Meat and Beans

Calories represent energy.

Carbohydrates

Carbohydrates provide us with ATP (energy).

• Two most important types: fructose (easy to absorb because it is a monosaccharide) and glucose (also a monosaccharide and the main carbohydrate in the blood).
• Other types: sucrose, maltose, and lactose. These are more difficult to absorb because they are disaccharides (two molecules linked).

Polysaccharides (Hard to Digest)

Polysaccharides are composed of many...

Understanding and Managing Stress

Concept of Stress

Stress, an uneasy experience of pressure, can stem from various sources: yourself, others, and the environment. Modern life's fast pace creates numerous pressures, leading to frequent stressful situations. Effective stress management starts with understanding its sources and how to address them.

Self-Inflicted Stress

Sometimes, we create our own stress. This isn't always negative. Eustress, or positive stress, can produce beneficial results. Its counterpart, distress, is the negative dimension of stress.

Environmentally Caused Stress

External factors can also induce stress. Imagine your crops are ready for harvest, but continuous rain creates worry and helplessness. This stress originates from...

Carbohydrates

• Monosaccharides: Glucose, ribose, fructose.
• Disaccharides: Maltose (two glucose molecules), sucrose (glucose and fructose).
• Polysaccharides: Cellulose and glycogen (chains of glucose).

Fatty Acids

• Cis-unsaturated fatty acids: Bended structure, loosely packed, low melting point, hydrogen atoms on the same side, liquid at room temperature, common in nature.
• Trans-unsaturated fatty acids: Straight structure, strongly packed, high melting point, hydrogen atoms on opposite sides, solid at room temperature, rare in nature.

Amino Acids and Proteins

Amino acids consist of an amino group (-NH2) and a carboxyl group (-COOH).

Common Amino Acids

Serine, glutamic acid, alanine, and glycine.

Amino Acid Structure

Amino acids linked together share identical...