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

Nerve Impulse Transmission Across a Synapse

The nerve impulse which has been transmitted along the membrane of the transmitter neuron reaches the end of its axon. At the end of the axon, the arrival of the nerve impulse causes neurotransmitters to be released into the synaptic cleft. Neurotransmitters bind to the membrane of the receptor neuron and generate a new nerve impulse. The new nerve impulse is transmitted along the membrane to the axon, where the whole process is repeated.

The Autonomic Peripheral Nervous System

The autonomic PNS consists of motor nerves which regulate the activity of the internal organs and control involuntary movements. The autonomic nervous system is divided into the sympathetic nervous system and the parasympathetic... Continue reading "Understanding Nerve Impulse Transmission and the Endocrine System" »

Key Characteristics of the Animal Kingdom

• Multicellular with differentiated tissues and organs
• Eukaryotic cells
• Heterotrophic: Feed on other living things
• Motile: Capable of active movement
• Sensitive to environmental changes
• Possess an internal or external skeleton
• Found in aquatic and terrestrial environments

Invertebrates and Vertebrates

• Invertebrates: Do not possess a spinal column (e.g., butterflies, sea urchins).
• Vertebrates: Possess a spinal column (e.g., cats, frogs).

Types of Body Symmetry

• Radial Symmetry: Body parts arranged around a central axis (e.g., starfish).
• Bilateral Symmetry: Body can be divided into two mirror-image halves (e.g., insects, vertebrates).

Animal Feeding Strategies

Dietary Classifications:

• Carnivores
• Herbivores
• Omnivores

Specific

Trigeminal Nerve (V3) Anatomy

The trigeminal nerve (V3), also known as the mandibular nerve, has an anterior trunk (mainly motor) and a posterior trunk (sensory). It supplies taste sensory innervation to the anterior part of the dorsum of the tongue via fibers of CN7. Before dividing into two terminal trunks, there are two lateral branches:

• Meningeal branch: Sensory, supplies the dura mater of the middle cranial fossa.
• Medial pterygoid muscle nerve: Motor nerve, supplies the medial pterygoid muscle from the deep side. It also innervates the tensor veli palatini and tensor tympani muscles.

Anterior Trunk Branches

• Buccal nerve: Sensory, supplies the skin of the cheek, mucosa of the posterior and inferior portion of the vestibule, and the buccal side

The Endocrine System: Signals and Outcomes

The endocrine system consists of signal senders, the chemical signals they transmit, and the resulting outcomes. The main signal senders are the endocrine glands, which include:

• Hypothalamus
• Pituitary gland
• Thyroid gland
• Parathyroid glands
• Adrenal glands
• Pancreas
• Gonads (Ovaries and Testicles)

Endocrine glands specifically send chemical signals (hormones) to different parts of the body. These hormonal signals generally cause slower, subtler changes compared to the nervous system, which uses electrical signals.

Hormones travel through the body via the bloodstream, but only the intended target cells respond. These cells are keyed with receptors that fit the hormone—much like matching puzzle pieces. The hormone... Continue reading "Essential Medical Terminology: Endocrine, Blood, and Heart Systems" »

Nervous System: The Body's Control Center

The Nervous System controls, processes, and responds to information, coordinating the body's activities.

Neuron: The Basic Unit of the Nervous System

The neuron is the basic structural unit of the nervous system. Neurons conduct impulses throughout the nervous system and consist of three regions:

• Axon
• Dendrites
• Cell Body

Dendrites and Axons: The Neuron's Extensions

Dendrites are extensions of the neuron that receive impulses and carry them toward the cell body.

The axon is an extension of the neuron that carries impulses away from the cell body toward other neurons, muscles, or glands.

Three Categories of Neurons

Neurons are categorized into three types:

1. Sensory Neurons: Carry impulses from the body to the spinal

MICROEVOLUTION

Changes that lead to the appearance of new species and groups that are closely related to each other.

MACROEVOLUTION

Leads to large groups of organisms after drastic change.

PUNCTUATED EQUILIBRIUM

The appearance of major groups of organisms took place as a result of drastic changes and the accumulation of gradual variations.

PHYSIOLOGICAL TREES

Visual representation of the evolutionary history of a group of organisms. A simplified diagram that, using a series of branches, shows the relationship between organisms.

SPECIATION

Two or more distinct species.

GEOGRAPHICAL BARRIERS

Examples are lakes, mountain ranges, and seas.

SEXUAL BARRIERS

Caused by anatomical changes that prevent mating from occurring.

PHYSIOLOGICAL BARRIERS

Incompatibilities... Continue reading "Evolutionary Processes and Theories: A Comprehensive Overview" »

Introduction

Humans are heterotrophs, meaning they cannot create their own organic matter. They obtain energy by ingesting substances from other organisms.

Food: Substances from other living things that are ingested.

Nutrients: Simple molecules contained in foods, necessary for life.

Eating: Conscious, voluntary process by which foods are taken from the outside environment.

Nutrition: Complex, unconscious, and mostly involuntary process by which foods are transformed into nutrients.

Carbohydrates (Glucides)

Energy-providing nutrients.

Monosaccharides

Formed only by one molecule.

• Examples: Glucose (cane sugar), fructose (fruit sugar)

Disaccharides

Formed by two molecules.

• Examples: Sucrose (cane sugar), lactose (sugar of milk)

Mono and disaccharides are sweets,... Continue reading "Nutrients: Essential Substances for Life" »

Describe the sources, targets, and primary effects of the hormones of calcium metabolism

The parathyroid gland is the hormone that affects Ca2+ concentration. When Ca2+ concentration is too low in the plasma, the parathyroid hormone secretion is stimulated, and vice versa. This parathyroid hormone can have several effects. It can send a signal to the bones and the osteoblasts will break down and more Ca2+ enters the blood. It can also stimulate the formation of 1,25 (OH)₂D to reabsorb Ca2+ in the intestines and kidneys so less Ca2+ is excreted, it also increases the excretion of phosphate ions. It also stimulates the reabsorption of Ca2+ in the GI tract. Calcitonin is a peptide hormone secreted by parafollicular cells in the thyroid gland. Calcitonin... Continue reading "Hormones of Calcium Metabolism and Stress Response Pathways" »

Infectious Diseases

Pathogenic Bacteria and Associated Diseases

Compare and contrast the morphological characteristics of various pathogenic bacteria given below and explore their role in human diseases.

• Bacillus anthracis: Anthrax
• Clostridium botulinum: Botulism
• Clostridium tetani: Tetanus
• Corynebacterium diphtheriae: Diphtheria
• Haemophilus influenzae: Influenza (flu); Bacterial Meningitis
• Mycobacterium tuberculosis: TB (Tuberculosis)
• Neisseria gonorrhoeae: Gonorrhea
• Salmonella Typhi: Typhoid Fever
• Shigella Dysenteriae: Dysentery
• Staphylococcus aureus: Boils and Pimples
• Streptococcus pneumoniae: Pneumonia
• Streptococcus pyogenes: Strep Throat; Scarlet Fever; Rheumatic Fever

Microbiology Concepts and Tests

Hemolytic Activity

Describe how hemolytic activity is... Continue reading "Key Pathogenic Bacteria and Tests" »

Pollination and Fertilization in Plants

Pollination is the mechanism to achieve the objective of transferring pollen grains, shed from the anther, to the stigma of a pistil. This transfer is termed pollination.

Kinds of Pollination

Depending on the source of pollen, pollination can be divided into three types:

• Autogamy
• Geitonogamy
• Xenogamy

Double Fertilization

After entering one of the synergids, the pollen tube releases two male gametes into the cytoplasm of the synergid. One of the male gametes moves towards the egg cell and fuses with its nucleus, thus completing the syngamy. This results in the formation of a diploid cell, the zygote. The other male gamete moves towards the two polar nuclei located in the central cell and fuses with them to produce... Continue reading "Pollination, Fertilization, and Reproduction in Plants and Humans" »