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

Viral Morphology

The morphology of the virion capsid is defined by its composition of multiple copies of a single protein or several different proteins, each encoded by a viral gene. A capsid, along with the nucleic acid it contains, is called a nucleocapsid. Virions exhibit two primary types of symmetry: helical and icosahedral.

Symmetry Types

Helical Symmetry

This is a helical protein structure with RNA or DNA protected inside it.

Icosahedral Symmetry

An icosahedral virus is a polyhedron composed of 20 identical, equilateral triangular faces.

In some viruses, the nucleocapsid is coated by an outer shell, or envelope, which is a fragment of the host cell's plasma membrane acquired as the virus emerges through a process called budding.

Complex Structures

Some... Continue reading "The Fundamentals of Virus Morphology and Replication" »

Staphylococcus

• Easily develops antimicrobial resistance
• Gram-positive cocci
• Catalase-positive
• Facultative anaerobes
• Not demanding in their nutritional requirements
• Grow in normal media
• Some pathogenic species are generally opportunistic pathogens, commensals
• Important in animal and human infections

Natural Habitat

Widespread in nature; found on human and animal skin, surfaces of objects, air, soil, water, and milk.

S. aureus

Main pathogen associated with infections; colonizes nasal passages and pharynx.

S. epidermidis

Produces skin lesions, wound infections; microbiota found in the skin, respiratory tract, and gastrointestinal tract.

S. saprophyticus

Associated with urinary tract infections.

Immunogens

• Polysaccharide A (specific for S. aureus)
  • Antiphagocytic
  • Antiplatelet
  • Activator

Forensic Aspects of Asphyxia

Carotid Artery Occlusion

Loss of consciousness typically occurs within 10-15 seconds of complete occlusion of the carotid arteries. This timeframe allows for the implementation of restraint mechanisms.

Differential Diagnosis at the Scene

Differential diagnosis is crucial and is made at the scene, considering:

• The victim's clothing state.
• Presence of extracervical lesions indicative of control or struggle.
• Severity of neck injuries.

The diagnosis of accidental etiology is based on a meticulous examination of the scene. A high blood alcohol level may explain the victim's low resistance or the possibility of accidental strangulation.

Forensic Pathology of Submersion (Drowning)

Definition and Types of Submersion

Death or pathological... Continue reading "Forensic Pathology: Asphyxia and Drowning Investigations" »

The Nervous System

Consisting of two types of cells:

• Neurons: consist of neuronal bodies, Dendrites (extensions where the nerve impulse enters the body), and axons.
• Glia (or Neuroglia): Made by the supporting structure of the nervous system, they collaborate in nutrition and feeding of neurons.

Nervous System Division

Central Nervous System (CNS), peripheral nervous system, autonomic (or vegetative) nervous system.

Central Nervous System

Comprising:

• Brain: Located in the skull, it consists of an internal gray substance and an external white substance. Surrounded by 3 membranes called meninges: Piamater, Arachnoid, Dura mater.

Parts:

• Cerebrum: Divided into hemispheres (left and right), weighing between 1200 and 1600g. It includes frontal, parietal, occipital,

Lung Cancer Impact: Eastern Europe and North America have the highest lung cancer incidence rates. Men are disproportionately affected, with rates 76% higher in men than in women in Eastern Europe and 69% higher in North America. However, incidence in women is increasing. The 5-year survival rate remains very low.

Risk Factors: Smoking accounts for a substantial portion of lung cancer deaths: 80% in men, 75% in women, and contributes to 17% of lung cancer cases in non-smokers. Smoking is also linked to 28% of all cancer deaths. Other risk factors include asbestos, radon exposure (mining or environmental), a diet low in vitamins A, C, E, and beta-carotene, as well as genetic and familial factors.

Lung Cancer Control: Effective control strategies... Continue reading "Lung Cancer: Incidence, Risks, and Diagnosis" »

The Nervous System

The nervous system is responsible for detecting and responding appropriately to stimuli that reach the organism. Receptor neurons are specialized to detect stimuli, while effectors carry out the nervous system's commands.

Sensory Organs

The Eye: Structure and Function

The eye is a complex sensory organ responsible for vision. Its primary components include:

• Sclera: The outermost, tough, protective white layer of the eye.
• Choroid: A thin, vascular membrane located between the retina and the sclera, rich in blood vessels that supply nutrients to the eye.
• Retina: The innermost layer at the back of the eye, containing photoreceptor cells (rods and cones) that convert light into neural signals.

The Ear: Functions and Regions

The ear performs... Continue reading "Human Body Systems: Anatomy and Key Functions" »

Understanding Health and Well-being

Health is a state of complete physical, mental, and social well-being, and not merely the absence of disease.

Health depends on individual lifestyle and personal behavior, including physical activity, environmental and social factors such as climate and pollution, and genetic information.

Myocardial Infarction (Heart Attack)

When blood flow through a vessel of the heart is blocked, blood stops flowing to an area of heart muscle, halting the supply of oxygen and nutrients. This leads to muscle tissue death and permanent heart damage. If the blockage is partial and reduces blood flow, it causes a sharp pain known as angina.

Symptoms of a Heart Attack

Symptoms start with pain or discomfort in the center of the chest,... Continue reading "Understanding Health, Heart Attacks, and Risk Factors" »

How Infectious Diseases Spread

Infectious diseases can spread through various means:

• Water: Consuming water contaminated with feces from humans or animals.
• Food: Eating fruits and vegetables irrigated with contaminated water or improper food handling.
• Animals: Through disease vectors. For example, the Anopheles mosquito transmits malaria.

Stages of Infectious Disease Development

The development of infectious diseases involves several stages:

• Infection: The organism enters the body.
• Incubation Period: The time from infection to the appearance of symptoms.
• Period of Manifestation: The disease is fully manifested, with symptoms like fever and pain.
• Period of Decline: Symptoms subside due to the immune system and medications.
• Convalescence: The patient recovers

Understanding Circulation and Blood Disorders

Pulmonary and Systemic Circulation

Pulmonary Circulation: Circulation through the lungs.

Systemic Circulation: Circulation to the rest of the body.

Vena Cava: Carries deoxygenated blood.

Coronary Heart Disease

Coronary Heart Disease: Refers to any disease that results in blockage of the coronary blood supply to part of the heart's muscular wall. The blockage causes partial deprivation of oxygen to the affected part and may result in the death of muscle cells.

Effects of Coronary Heart Disease

If a large part of the heart is affected, the person may die instantly. If a small region is affected, it may recuperate.

Atherosclerosis

Atherosclerosis: The most common form of hardening of the arteries. It begins... Continue reading "Understanding Pulmonary and Systemic Circulation & Blood Disorders" »

Occupational Hazards

Hearing Loss

Occupational hearing loss, or deafness, is the functional deficit that occurs when an individual experiences a partial or complete loss of hearing. This is determined by the hearing threshold, which is the weakest sound stimulus that a particular ear can perceive. While the terms "deafness" and "hearing loss" are often used interchangeably, they are distinct conditions.

Pneumoconiosis

Pneumoconiosis encompasses a group of lung diseases caused by inhaling and accumulating inorganic dust particles, and the subsequent reaction within lung tissue. Disease development depends on the dose of inhaled and retained particles, the particles' biological activity, the induced tissue reaction, and individual sensitivity.

Drug