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

Overview of the Nervous System

Cervical Plexus

Supplies the skin of the neck and a deep one that supplies most of the muscles of the neck and the diaphragm muscle.

Brachial Plexus

Three primary trunks:

• 1^st primary trunk: C5-C6
• 2^nd primary trunk: C7
• 3^rd primary trunk: C8-T1

Three secondary trunks:

• External anterior trunk
• Internal anterior trunk
• Posterior trunk

Lumbar Plexus

Gives side branches to the psoas muscle.

Terminal branches:

• Obturator nerve, which serves the thigh.
• Femoral nerve, which extends the knee (quadriceps).

The innervation of this plexus territory does not pass the knee.

Sacral Plexus

Gives collateral branches to the muscles of the hip.

Delivers a single terminal branch, the thickest nerve, called the sciatic nerve.

Innervates the hamstrings and... Continue reading "Overview of the Nervous System Development" »

Orthopedic Surgical Instruments

Cutting Bone Instruments

• Hand and Power Saws: Used for precise bone cutting.
• Gouges: For scooping out bone.
• Hammers and Osteotomes: Used together for bone shaping and cutting.
• Periosteal Elevators: For lifting the periosteum from bone.
• Shears: For cutting tissue or bone.
• Tweezers: For grasping and holding tissues.
• Drill Bits: For creating holes in bone.

Gynecological Instruments

Valves, Retractors, and More

Common gynecological instruments include valves, retractors, and other separators used during examinations and procedures.

Otolaryngology (ENT) Instrumentation

Exploration and Surgical Instruments

• Instruments for the Ear:
  • Otoscopes: For examining the ear canal and eardrum.
  • Drills: Used in ear surgery.
  • Angled Forceps: For precise

Nervous System Anatomy

The nervous system is a complex network responsible for coordinating actions and transmitting signals throughout the body. It can be broadly divided into several key components:

Somatic Nervous System

The Somatic Nervous System is composed of mixed nerves, containing both sensory and motor axons. These nerves innervate somatic effectors, primarily skeletal muscles.

Central Nervous System (CNS)

The Central Nervous System has a sensory or afferent division that brings information from sensory receptors in the periphery. This includes visual, auditory, somatosensory, and chemoreceptor information. This information is transmitted to higher levels, reaching the motor cortex. The motor or efferent division carries information towards... Continue reading "Nervous System Anatomy: Somatic, Central, and Spinal Components" »

Sensory Receptors: Gateways to Perception

Sensory receptors are specialized nerve cells that capture and transform stimuli into nerve impulses. These vital structures allow the body to perceive and react to its environment.

Classification of Receptors by Stimulus

According to the stimulus to which they are sensitive, receptors are classified as:

• Chemoreceptors: Sensitive to chemical substances.
• Mechanoreceptors: Sensitive to mechanical stimuli such as sound, pressure, friction, or gravity.
• Thermoreceptors: Sensitive to temperature variations.
• Nociceptors: Sensitive to intense pressure, pain, and potentially damaging stimuli.

Location of Sensory Receptors

Sensory receptors are found throughout the body and can be broadly categorized by their location:... Continue reading "Understanding Sensory Receptors and Human Senses" »

Plant Photosynthesis: C3, C4, and CAM Pathways

C4 Plants

C4 metabolism has a higher energy cost than C3, requiring 5 ATP and 2 NADPH per CO2 fixed. C4 plants are adapted to tropical, subtropical, relatively dry environments with bright illumination and can withstand high and low relative humidity. They fix CO2 using PEP carboxylase and then pump it to the bundle sheath cells.

C3 Plants

C3 plants use 3 ATP and 2 NADPH and are adapted to temperate climates with moderate temperatures and high relative humidity.

Exogenous Factors Affecting Photosynthesis

• Light
• Concentration of CO2 and O2
• Temperature
• Availability of water and nutrients

Endogenous Factors Affecting Photosynthesis

Type of plant (C3, C4, or CAM), stomatal density, leaf area, leaf age, hormone... Continue reading "Photosynthesis: C3, C4, and CAM Pathways, Pigments, and Factors" »

Exception to the Cell Theory: Viruses

Is a self-replicating biological entity capable of using cellular machinery. It is a potentially pathogenic agent composed of a capsid protein surrounding the nucleic acid, which can be DNA or RNA. This structure can, in turn, be surrounded by the viral envelope, a lipid layer with different proteins, depending on the virus's life cycle. A virus always needs the metabolic machinery of an invaded cell to replicate its genetic material, producing many copies of the original. This process underlies the destructive power of viruses because they can damage or destroy the cell.

Features of Viruses:

• Size: Extremely small.
• Crystallization Structure: Having a volume and identical form, viral particulates tend to order

Angiosperms: The Flower

1. Floral Peduncle: The peduncle is the stalk that connects the flower to the plant.

2. Floral Receptacle: The receptacle is the expanded end of the peduncle where the floral parts (whorls) are attached. These include the calyx, corolla, androecium, and gynoecium.

Calyx

3. Sepals: The calyx consists of sepals, which are modified leaves that protect the developing flower bud.

Gynoecium (Female Reproductive System)

4. Ovary: The ovary contains one or more ovules (seminal primordia). Each ovule is attached to the ovary wall by a short stalk called the funiculus. The region where the ovule is inserted is called the placenta.

5. Carpels: The gynoecium is composed of one or more carpels, which are fused, bottle-shaped structures.... Continue reading "Understanding Angiosperm Flower Anatomy and Reproduction" »

Male Reproductive System

Glands Attached

• Seminal Vesicles: These two glands produce 60% of the seminal fluid, which contains fructose. They generate peristaltic contractions in the ejaculatory ducts. The clotting proteins in the semen form a weak coagulum in the vagina, keeping the semen in the deeper regions.
• Prostate: Nut-shaped, it surrounds and is traversed by the urethra. Prostatic fluid contributes 13-22% of semen volume and contains calcium, phosphate ions, and a clotting enzyme. The prostate's volume can increase with age (benign prostatic hyperplasia). Symptoms include increased prostate volume, difficulty urinating, and post-urination dribbling.
• Cowper's Glands: These glands clear the urethra of residual urine before sperm ejection. They

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

Pelvis and Leg Bone Anatomy Q&A

1. Which bones form the pelvic girdle?
   The pelvic girdle is formed by the two innominate bones (hip bones), the sacrum, and the coccyx.
2. What is the pubic symphysis?
   It is the cartilaginous joint connecting the left and right pubic bones.
3. Which bones fuse to form the innominate (hip) bone?
   The ilium, ischium, and pubis fuse to form each innominate bone.
4. What is the function of the iliac crest?
   It serves as an important attachment point for abdominal and hip muscles.
5. Where does the femoral head articulate with the innominate bone?
   The head of the femur articulates within the acetabulum, a socket on the innominate bone formed by the fusion of the ilium, ischium, and pubis.
6. What is the function of the greater and lesser trochanters