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Human and Plant Biology: Homeostasis, Thermoregulation, Blood Sugar, and Tropisms

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Still the Eye

Cornea Lens: More spherical lens with shorter focal length
Thinner lens with longer focal length (requires less refraction)
Suspensory Ligaments: Distant = flat; Near = round/thick

Homeostasis

Homeostasis: Maintenance of a constant internal environment despite changes in surroundings.
Control Center: The hypothalamus in the brain decides on the appropriate response. Receptors: In the skin and brain, detect changes in the body. Effectors: E.g., sweat glands, body hair, and thyroid glands change to increase/decrease body temperature.

Thermoregulation

Thermoregulation: If the body is too cold or hot, body temperature is adjusted to what it should be (negative feedback mechanism). It involves receptors linked to the hypothalamus, which
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Zika Virus: Transmission, Symptoms, and Prevention

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Zika is a mosquito-borne disease transmitted by the same mosquito that carries the dengue virus. There have also been cases of transmission through sexual intercourse.

Transmission

Most people get Zika from a mosquito bite. Mosquitoes become infected when they feed on the blood of a person already infected with the virus, and when they bite others, they can transmit the virus. Other forms of transmission include:

  • A pregnant woman can pass the Zika virus to her fetus during pregnancy or at the time of birth.
  • Zika can also be transmitted through sexual intercourse and blood transfusion.

Symptoms

Zika can cause incomplete brain development in fetuses. Common symptoms include fever, rash, joint pain, and conjunctivitis.

Prevention

To reduce the risk of

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Woman called Donna Truhana

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SPERMATOZOA 

Spermatozoa, or male gametes, are small, mothie cells (capable of movement). They carry the hereditary information from the father.
-The head, which contains the cell nucleus with the hereditary material
-A mid-piece, the many mitochondria of which generate the enrgy required for movement.
-The tail, which is called flagellum, enables them to move.
THE FORMATION OF SPERMATOZOA
The formation of spermatozoa, takes place in the seminiferous tubules, which include the interstitial cells that segretate testosterone. The walls of these tubules contain cells called germ cells, which are constantly multiplying themselves. As they multiply, the cells move towards the end of the tube and gradually mature until they become spermatozoa. The process
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Essential Nutrients and Their Role in Health

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Food and Essential Nutrients

Food is our source of nutrients. Nutrients are biomolecules our body needs to sustain vital functions. They are the chemical components of food, the building blocks and energy sources our cells require to live.

Basic Nutritional Requirements

  • Energetic: Some nutrients are broken down in mitochondria to extract energy.
  • Structural: Some nutrients are building blocks of body structures.
  • Regulatory: Some nutrients are necessary in small quantities to regulate body metabolism.

Carbohydrates (Glucids)

Biomolecules present in bread, cereals, potatoes, pasta, etc. They provide energy to cells, and some of them must be consumed on a regular daily basis.

Simple and Complex Glucids

Simple Glucids (Sugars)

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Sensory Systems and Nervous Coordination

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Receptors

Internal receptors perceive changes inside the body, such as a rise in blood pressure. External receptors perceive stimuli in the external environment.

Types of Receptors

  • Mechanoreceptors: Perceive mechanical stimuli (pressure).
  • Thermoreceptors: Perceive changes in temperature.
  • Chemoreceptors: Detect chemical substances in the air, water, etc.
  • Nociceptors: Perceive pain stimuli.
  • Photoreceptors: Light sensitive.

Nervous System

The nervous system analyzes internal and external stimuli perceived by receptors, generating responses. It carries out this function through nerve impulses transmitted by cells called neurons. This system coordinates fast, short-lived responses (e.g., muscle contraction).

Endocrine System

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Internal leakage in

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Sensory receptors are responsible for perceiving infortion, which they convert into a nerve impulse. The nerve impulse travels to the brain and produces a feeling.

Photoreceptors: they detect light stimuli and are located in the eye. Some of them respond to dim light conditions and produce black and white vision; others respond to bright light and produce colour images.
Mechanoreceptors: they are stimulated by mechanical changes such as pressure, contact or sound waves. They are several receptors in the skin, muscles and joints. Auditory receptors are included in this group.
Chemoreceptors: they respond to chemical changes. Taste and smell receptors belong to this group.
Thermoreceptors: they detect temperature changes. Some skin receptors are
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Exercise Physiology: Antioxidants, Fatigue, and Body Composition

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Antioxidants and Exercise

Key antioxidants include Vitamin C, Vitamin E, Carotenoids, Glutathione (GSH), and Coenzyme Q10 (Q10).

Enzymatic Antioxidant Systems

  • Superoxide Dismutase (SOD)
  • Catalase
  • Glutathione Peroxidase

Functions of Antioxidants

  • Neutralize free radicals by donating electrons (e-) and hydrogen ions (H+).
  • Decrease lipid peroxidation both at rest and after exercise.
  • Note: Supplementation may not necessarily decrease overall oxidative stress markers.
  • Note: Vitamin E supplementation does not appear to decrease neutrophil count after exercise.

Benefits and Roles of Oxidative Species

  • Reactive Oxygen Species (ROS) and Reactive Nitrogen Species (RNS) are important for cellular development, function, and as stimuli (cellular messaging) – involved
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The Cardiovascular System: Pulmonary and Systemic Circulation

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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

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Orthodontic Malocclusion: Crossbites, Crowding, and Treatment Approaches

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Orthodontic Malocclusion: Crossbites, Crowding, and Treatment Approaches

Types of Crossbite

A crossbite occurs when the upper teeth fit inside the lower teeth. It can be classified based on its origin:

  • Dentoalveolar Crossbite

    Also known as compressed, inclined, or altered crossbite. In this type, the dental arch is narrowed even though the skeletal width is correct. If the base of the palatal vault is wide, but the dentoalveolar process leans inward, the crossbite is DENTAL, caused by a distortion of the dental arch itself.

  • Basal Crossbite

    Also known as compression, inclined, or symmetric crossbite. If the palatal vault is narrow and the maxillary teeth lean outward but are nevertheless in crossbite, the crossbite is SKELETAL. There can be dental

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Endocrine and Musculoskeletal Systems: Functions and Anatomy

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The Endocrine System

The endocrine system is a set of organs and tissues responsible for secreting hormones. It is distributed throughout the body, similar to the nervous system. However, the endocrine system uses chemical substances instead of nerve impulses.

Types of Hormones and Glands

  • Pituitary: Located in the head.
    • Growth hormone: Stimulates the growth of all body tissues, especially the skeleton.
    • Thyroid-stimulating hormone: Regulates the production of thyroid hormones.
  • Testes: Male gonads.
    • Testosterone: Stimulates the production of sperm and the development of secondary sexual characteristics.
  • Thyroid: Located in the neck, in front of the trachea.
    • T3 and T4: Increase cell metabolism, oxygen consumption, protein synthesis, and glucose utilization.
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