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

Laryngeal Skeleton and Hyoid Bone

The hyoid bone is located in the skeleton of the larynx and is formed by various cartilages.

Key Laryngeal Cartilages

• Hyoid Bone: An irregular bone featuring two processes on each side.
• Thyroid Cartilage: Shaped like an "open book" with a prominent thyroid notch. It features superior and inferior prolongations on its side plates.
• Cricoid Cartilage: An unpaired cartilage that articulates posteriorly with the arytenoid cartilage.
• Epiglottic Cartilage: Shaped like a bicycle saddle.

These structures are reinforced by membranes, tendons, and laryngeal muscles, all covered by the laryngeal mucosa.

Hyoid Muscle Groups

The hyoid muscles are located in the anterior neck and are divided into suprahyoid and infrahyoid groups.

Infrahyoid

Mutated Acetylcholine Receptors and Muscle Function

If a child is born with a mutated acetylcholine receptor in a muscle cell, the depolarization of the muscle cell membrane will not be initiated, resulting in no intracellular calcium release.

Excitation-Contraction Coupling Mechanism

Excitation-contraction coupling occurs because intracellular calcium is released, allowing myosin to bind to actin, which in turn permits the shortening of myofibrils.

Impact of Spinal Cord Ventral Horn Damage

Damage to the medial ganglion of the ventral horns of the spinal cord primarily affects the movement of the limbs.

Effect of Intracellular Calcium Depletion in Muscle

If intracellular calcium is removed from a muscle fiber, it blocks the excitation-contraction...

Centrioles: Anatomy and Cellular Role

The centriole is a small organelle situated in the middle of an ill-defined area known as the centrosphere, existing in all cells capable of dividing. They are identical to the basal corpuscles of cilia and flagella.

Structure

Most cells contain two centrioles located near the nucleus or within a notch of the Golgi apparatus. This perpendicular pair is called a Diplosoma. Each centriole has a cylindrical shape, distinguished by a proximal end (near the center of the cell) and a distal end, which features a cartwheel complex.

• Wall Composition: Formed by nine triplets of microtubules.
• Microtubule Arrangement: The three tubules (A, B, and C) are closely associated, with the virtual axis passing through the center

The Endocrine System

Function: Responsible for metabolic regulation.

Hormones: Chemical substances secreted into internal body fluids that exert physiological control over target cells throughout the body.

Types of Hormones

• Local Hormones: Acetylcholine, which is secreted by nerve endings, and secretin, which stimulates the duodenal wall to produce aqueous pancreatic secretion.
• General Hormones: Secreted by specific endocrine glands and carried by the blood throughout the body to produce various reactions.

Chemistry of Hormones

1. Steroid Hormones (Derived from Cholesterol)

• Adrenal Cortex: Cortisol, aldosterone.
• Ovaries: Estrogen, progesterone.
• Testicles: Testosterone.
• Placenta: Estrogen, progesterone.

2. Tyrosine Amino Acid Derivatives

• Thyroid Hormones:

Acrylic Resins: Polymerization Stages and Properties

Polymerization Stages

Plastic Stage (Pastoso Period)

The Plastic Stage (Pastoso Period) is the interval between Period 1 and Period 3 of the monomer-polymer physical interaction.

Working Time (D-Time)

The Working Time (D-Time) is the time elapsed between the end of Period 2 and the beginning of Period 4. This is the duration during which the material maintains a plastic consistency suitable for manipulation.

Factors Modifying Working Time

Key factors that modify the working time include:

• Temperature
• Polymer particle size
• Polymer molecular weight

Monomer-Polymer Interaction: Chemical Periodicity

The chemical periodicity of polymerization involves the following steps:

1. Activation: Formation of free radicals

Physiological Adjustments to Regular Physical Exercise

Cardiovascular System Adaptations

• Increased coronary flow, capillary permeability, and capillary density.

Adaptive Responses of Blood Pressure to Exercise

• Increased blood pressure during exercise and decreased resting blood pressure.

Adaptations in the Respiratory System to Exercise

• Increased frequency and depth of respiration.

Blood Flow Distribution During Exercise

• Increased blood flow in active muscles at the expense of inactive organs.

Cardiac Adaptations: Concentric Hypertrophy

• Corresponds to concentric hypertrophy of the heart, often induced by strength training.

Functions of Respiratory System Adaptations

• To meet O2 demands, eliminate excess CO2, and regulate pH.

Cardiac Output Responses to Exercise

• Trained

Anthropometry: Measuring the Human Body

Anthropometry is a branch of anthropology focused on the measurement of different human body parts. It provides crucial data for understanding human variation, growth, and development.

Human Body Types: Sheldon's Classification

William Sheldon classified human body types based on the predominance of three fundamental components, known as somatotypes:

• Endomorph: Characterized by a predominance of curves and significant visceral development.
• Mesomorph: Defined by the dominance of muscle and bone, indicating a robust and athletic build.
• Ectomorph: Marked by weak muscular and visceral development, typically featuring long and slender limbs.

Growth and Development of Body Systems

Nervous System Growth

The nervous system...

Nuclear Ultrastructure and Morphology

1. Nuclear Irregularity: Through electron microscopy (EM), it is observed that the morphology has a more irregular contour than seen in optical microscopy (OM). These irregularities are related to:

• Aging and cellular maturation
• Nuclear metabolism and exchange with the cytoplasm

The Nuclear Envelope Structure

2. Nuclear Envelope: The nucleus is surrounded by a double membrane formed by an inner and outer nuclear membrane that bind at the nuclear pore level.

• External Membrane: It has a thickness of 60 Å. It is in continuity with the cisternae of the MPU (Endoplasmic Reticulum) and, like it, is covered by ribosomes.
• Internal Membrane: It has a thickness of 60 Å. It relates to the chromatin and proteins or the nuclear

Cerebral and Basilar Arteries

The carotid artery supplies 80% of the oxygen to the cerebral hemispheres. The two internal carotid arteries branch into the middle cerebral arteries, which provide 60% of the brain's oxygen supply. The anterior communicating artery connects the right and left middle cerebral arteries.

Two vertebral arteries (left and right) ascend along the spinal cord and merge at the base of the skull to form the basilar artery. This artery supplies the medulla, pons, and other brainstem structures.

Circle of Willis

1. Frontal lobes
2. Temporal lobes
3. Middle cerebral artery (right and left)
4. Anterior cerebral artery
5. Posterior cerebral artery
6. Basilar artery
7. Vertebral arteries (right and left)
8. Spinal cord
9. Internal carotid artery
10. Anterior communicating

Periodontitis

Definition: Infectious destruction of the periodontal ligament and alveolar bone.

Classification

• Early
• Adult
• Refractory
• HIV-associated
• Periodontal lateral abscess
• Systemic pathology

Developing Periodontal Lesion

The process begins with an initial injury and cellular activity in the attached gingiva, causing inflammation. Early lesions and further cellular activity ignite connective tissue collagen destruction, initiating the lesion. The lesion sets, and a pocket epithelium is formed.

Host Factors

The immune system (lymphocytes B and T, macrophages, and others) plays a key role.

Bacterial Factors in Periodontitis

Bacterial factors include adhesion, multiplication, evasion of host defenses, enzymes, endotoxins, leukotoxins, proteases, IgA and...