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

Perineum Anatomy

Perineum Structures

The perineum is a diamond-shaped space between the pubic symphysis (anteriorly), the coccyx (posteriorly), and the ischial tuberosities (laterally), lying just inferior to the pelvic diaphragm (levator ani and coccygeus).

It is divided transversely into two triangles:

• The anterior is the urogenital triangle, which includes the external genitals.
• The posterior is the anal triangle, which contains the anus.

The perineum is also divided into superficial and deep layers, with some muscles common to men and women.

Muscles of the Perineum and Pelvic Floor

Muscles making up the Urogenital and Anal (Pelvic) triangles/diaphragms include:

• Urogenital diaphragm: Superficial and intermediate planes
• Sphincters: Internal and external

Elastic Fibers

Elastic fibers maintain the position of alveoli and bronchioles. When fibers recoil during exhalation, they reduce the size of alveoli and push air out.

Pneumocyte Type I

Pneumocyte type I cells are squamous epithelial cells that are unusually thin, providing an ideal site for gas diffusion.

Pneumocyte Type II

Pneumocyte type II cells are scattered among the squamous cells and produce surfactant.

Breathing

Deep breathing, also known as diaphragmatic breathing, involves the contraction of the diaphragm to change the volume of the lungs, allowing air to be exhaled passively. Shallow breathing, or costal breathing, occurs when the rib cage alters its shape, changing the thoracic volume.

Dalton's Law

Dalton's Law states that the partial pressure...

Two Main Circuits of the Cardiovascular System

Pulmonary Circulation

Pulmonary circulation refers to the circulation of blood in which deoxygenated blood is pumped from the heart to the lungs and oxygenated blood is returned back to the heart. Pulmonary circulation only occurs between the heart and the lungs.

Systemic Circulation

Systemic circulation refers to the circulation of blood in which oxygenated blood is pumped from the heart to the body and deoxygenated blood is returned back to the heart. Systemic circulation occurs between the heart and the entire body.

Pericardial Sac

The pericardial sac is the outermost layer of the heart. It surrounds the heart and protects it.

Heart Valves

Atrioventricular (AV) Valves

The AV valves prevent backflow into...

Auto or Self Antigens

Antigens present in one's own cells.

Altered by the action of bacteria, viruses, chemicals, or drugs as a non-self.

Auto antibody

Altered cell (Auto Ag) - elicits the production of Antibody.

Autoimmunity (misnomer, alternative = auto allergy)

Immune response of auto Ab against self Ag.

Humoral or cell-mediated immune response against the constituents of the body's own tissues.

There are more than 80 different kinds of diseases caused by autoimmunity.

Causes of Autoimmune Diseases

Sequestered or Hidden antigens

Ag in the secluded places - are not accessible to the immune system.

Neo antigens

Altered or Modified Antigens – by physical (irradiation), chemical (drugs), or microbial agents (intracellular viruses).

Cessation of Tolerance

It...

Glycolysis and the Krebs Cycle

The Krebs cycle (also known as the citric acid cycle or tricarboxylic acid cycle) is named after its discoverer, Hans Krebs, who proposed the key elements of O₂ consumption in an amount disproportionate to the amounts added. Based on experimental observations, Hans Krebs proposed a cyclic pathway and cell reactions. The sequence, being a functional unit of all organisms, has a very coordinated and specific operation of all its organelles. However, within all this perfect machine, it is paramount that it takes energy for all this machinery to work to perfection. Cells use energy in the form of ATP (adenosine triphosphate). This is a molecule consisting of one molecule of adenine, a ribose, and three phosphate groups....

Cell Nucleus: Structure and Function

The nucleus, a defining structure of eukaryotic cells, controls cellular activities and transmits hereditary information across generations.

Morphology

The nucleus can mirror the cell's shape or be irregular.

Size

Nuclear size correlates with cytoplasmic volume and the cell's proliferative capacity; it tends to be larger in actively dividing cells.

Structure

The nucleus exhibits two distinct periods: interphase and mitosis. During interphase, the following are present:

• Nuclear Membrane: A double-layered structure enclosing the nucleus, separating it from the cytoplasm. It regulates the passage of ions and small molecules.
• Nucleoplasm: This consists of nuclear sap, the nucleolus, and chromatin.

Chromosomes

Chromosomes...

DNA and RNA Structure

A nucleoside is formed when a pentose sugar combines with a nitrogenous base (NB). Adding a phosphate group to a nucleoside creates a nucleotide. Nucleotides are linked by O-glycosidic phosphodiester bonds. DNA adopts a right-handed double helix structure, with hydrophobic NBs at the core and hydrophilic pentose and phosphate groups on the exterior. The major groove serves as the interaction site for replication, while the minor groove contributes to structural maintenance. Approximately 10 base pairs span 3.4 nm.

Ribosomal RNA (rRNA)

Ribosomes consist of two subunits: a large subunit (50S in prokaryotes, 60S in eukaryotes) and a small subunit (30S in prokaryotes, 40S in eukaryotes).

DNA Replication

DNA replication must be...

Meiosis and Genetic Variation

Question 58

Which of the following occurs in meiosis but not in mitosis?

B) synapsis of chromosomes

Question 59

Crossing over normally takes place during which of the following processes?

B) meiosis I

Question 60

Homologous pairs of chromosomes align opposite of each other at the equator of a cell during _____.

B) meiosis metaphase I

Question 61

When homologous chromosomes cross over, what occurs?

C) Corresponding segments of non-sister chromatids are exchanged.

DNA Structure and Replication

Question 62

Which of the following people conducted the experiments that demonstrated that DNA is the genetic material of bacteriophages?

B) Avery, Hershey and Chase

Question 63

One type of virus that infects bacteria is called a

A) phage.

Question

Embarrassment:

When something is sudden and unexpected, onlookers are amused. It is a social mistake and makes the person the center of attention. Feeling empathetic for someone else's embarrassment is a display of care. People are often forgiven for their mistakes because they blush, which makes them feel smaller. Embarrassment peaks during teenage years (pregenual ant. cingulate cortex).

Shame:

Shame occurs when a person has failed to live up to expectations or has done something morally wrong. Onlookers are angry, and it often involves poor performance or hurting someone's feelings by failing to meet their expectations.

Guilt:

Guilt is the result of failing to perform one's duty, such as lying, cheating, or stealing (Medial prefrontal, visual...

Complete the statements.

1. There are 206 bones in the skeletal system of an adult.
2. Babies are born with almost 300 bones in their body.
3. The largest bone in the body is the femur.
4. The only floating bone is called the hyoid and it is located under the tongue.
5. The skeletal system has two main jobs: protect and support.

Complete the table with the functions of the skeletal system.

Label the parts of the skeletal system.

• Bones: They