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

Week 1: The Heart

Purpose of the Cardiovascular System

To provide adequate blood flow to all tissues/organs according to immediate needs.

Heart Contractions

• Systole: Periods of contraction
• Diastole: Periods of relaxation

Note: The atria contract simultaneously, followed by simultaneous ventricular contraction.

Blood Vessels

• Arteries: Carry blood away from the heart.
• Veins: Carry blood towards the heart.

Intrinsic Conduction System

1. Sinoatrial (SA) Node (Pacemaker): Generates impulses in the right atrial wall. Depolarizes 80-100 times per minute, modified by the autonomic nervous system to approximately 75 times per minute.
2. Atrioventricular (AV) Node: Impulses pause here for 0.1 seconds, allowing the atria to complete contraction. Generates impulses 40-60

Osmosis

Osmosis is the diffusion of water through a selectively permeable membrane. Water molecules move from an area of higher concentration to an area of lower concentration.

Isotonic Solutions

Isotonic means "same strength" and refers to the solute concentration. In isotonic solutions, water moves equally in both directions. For example:

• Animal cells: Water goes in and out.
• Plant cells: Water goes in and out.

Hypertonic Solutions

Hypertonic means "stronger." In hypertonic solutions, there is a net movement of water molecules out of the cell, causing it to shrink. For example:

• Animal cells: Water goes out.
• Plant cells: Water goes out.

In a hypertonic environment, the outside is more concentrated than the inside of the cell. The cell shrinks because...

Endocrine, Exocrine, and Mixed Glands

The endocrine system is composed of glands that secrete hormones. Hormones are chemical messengers that travel through the blood and exert specific actions on certain organs, known as target organs.

• Endocrine glands discharge hormones directly into the bloodstream.
• Exocrine glands discharge substances onto the body's surface through excretory ducts.
• Mixed glands combine the features of both endocrine and exocrine glands.

Endocrine System Functions

Hormones are key regulators of metabolism, reactions, and responses to states of alarm.

Endocrine Gland Characteristics

• Lack excretory ducts
• Generally small in size
• Act in small doses
• Can be formed as independent bodies, arranged in clusters, or within other organs

Pituitary

Human Reproduction

Sexual Reproduction

• Egg + sperm = zygote
• Viviparous development inside the mother

Sexual Reproduction includes:

• Gamete production methods
• Fertilization: zygote
• Development of the zygote: embryo
• Childbirth
• Child Development: Adult

Stages of Sexual Maturity

Children: Birth-10 years

• Primary sex characteristics

Puberty: 10-11 years

• Develop secondary sexual characteristics
• First menstruation
• Production of sperm

Adolescence

• The body prepares for reproduction

20-23 years

• Adult: end of development

Female Reproductive System and Gametes

Female internal organs:

• Ovaries: matures the egg
• Fallopian tube: connects ovary and uterus
• Vagina: connects the uterus to the outside
• Clitoris: sensitive due to a high number of nerve endings
• Labia minora: lines the external

Respiration: Concepts and Types

There are two types of respiration:

• A) Cellular or Internal Respiration: This is the use of oxygen by cells. It involves oxidizing complex organic molecules to obtain energy. This process produces CO2 and water as byproducts. Cellular respiration occurs in the mitochondria of the cell.
• B) External Respiration: This is the intake of oxygen and the output of carbon dioxide from the body. It occurs due to gas exchange across specialized respiratory surfaces. These surfaces must be very thin to allow for gas passage. They must also be wet, as gases dissolve in liquid before crossing. These surfaces are typically coated with a network of blood capillaries to facilitate the entry of oxygen and the exit of carbon dioxide.

Stem cells (or stem cells) are cells that have not completed their differentiation, either by being part of an embryo a few days old, or by being part of nature's reserves of immature cells in the adult organism.

Characteristics of Stem Cells

The key characteristics of stem cells are:

1. Self-renewal: The ability to produce more stem cells.
2. Differentiation: The origination of daughter cells of various types, which are converted by differentiation into specialized cell types.

Different Types of Stem Cells

Stem cells can be classified into the following types:

Totipotent Cells

There are about two hundred types of specialized cells, and all of them originate from unspecialized stem cells or differentiated cells. The first cell of every living thing, the...

Echinoderms

Phylum: Echinodermata

• Sea stars (starfish)
• Sea urchins
• Sand dollars
• Sea cucumbers
• Brittle stars

Key Features:

• Symmetry: Larvae: Bilateral; Adults: Pentaradial
• Body Covering: Spiny skin, endoskeleton made of calcium carbonate
• Movement: Tube feet powered by water vascular system
• Nervous System: No brain; nerve ring with radial nerves
• Circulation: Water vascular system (no true circulatory system)
• Respiration: Diffusion via tube feet or skin gills
• Reproduction: Mostly external fertilization; can regenerate lost parts
• Habitat: Marine only (no freshwater/terrestrial species)

Water Vascular System

A hydraulic system for movement, feeding, and respiration.

Frequently Asked Questions

1. What type of symmetry do adult echinoderms have? Pentaradial symmetry
2. Which

Core Concepts in Biology

Biodiversity

Species that inhabit or have ever inhabited the Earth.

Adaptation

The accumulation of changes in a living being to suit the environment in which it lives.

Types of Adaptation

• Structural: Affects organs and allows for specific functions, e.g., birds' beaks.
• Physiological: Affects the organism's function and metabolism.
• Behavioral: Actions that provide advantages, e.g., migration.

Evolutionary Theories

Biodiversity and Evolution

Slow changes in living beings over millions of years.

Fixism (Georges Cuvier)

Organisms were created through divine creation and became extinct due to catastrophes. This theory posited that species could not change, a view contrasted by later evolutionary theories.

Lamarckism (Jean-Baptiste de

Understanding Shigellosis: Causes and Treatment Challenges

What is Shigellosis?

Shigellosis is a significant public health threat in both developed and developing countries. It is an infectious disease caused by a group of bacteria known as Shigella. The genus Shigella includes four pathogenic serogroups: Shigella dysenteriae, Shigella flexneri, Shigella sonnei, and Shigella boydii. Shigellosis typically causes symptoms such as diarrhea, fever, and stomach cramps.

How is Shigellosis Contracted?

Individuals can contract shigellosis by ingesting contaminated food or water, or through direct contact with the stool of an infected person. This highlights the ease of transmission and the importance of hygiene.

Current Treatments and Emerging Resistance

Antibiotic...