Bio Notes

Excretory System

• Function: To remove wastes from the body.

  • Wastes include undigested food and byproducts of chemical reactions.

• Influence of Water on Blood Concentration:

  • High water intake:

    • More water absorbed from the large intestine.

    • Kidneys produce greater volume of dilute urine.

  • Low water intake:

    • Less urine produced.

    • More concentrated urine.

• Related Systems:

  • Endocrine System

  • Nervous System

Nervous and Endocrine Systems Comparison

• Speed of Message:

  • Endocrine: Slow

  • Nervous: Fast

• Speed of Response:

  • Endocrine: Usually slow

  • Nervous: Immediate

• Duration of Response:

  • Endocrine: Long lasting

  • Nervous: Short

• Spread of Response:

  • Endocrine: Usually slow

  • Nervous: Very localized

• How Messages Travel:

  • Endocrine: Through circulatory system (in bloodstream)

  • Nervous: Along nerves and across synapses

• Types of Message:

  • Endocrine: Hormones (chemicals)

  • Nervous: Electrical impulses and neurotransmitters (chemicals)

Nervous System Composition

• Composed of:

  • Central Nervous System (Brain and Spinal Cord)

  • Peripheral Nervous System (Nerves connecting CNS to the body)

• Neurons:

  • Building blocks of the nervous system.

  • Axons group to form nerves.

  • Types of Neurons:

    • Sensory Neurons: Carry impulses generated by stimuli to CNS.

    • Interneurons: Relay impulses within CNS.

    • Motor Neurons: Carry impulses to effectors (muscles or glands).

Complex Actions and Conscious Response

• More complex actions involve many interconnecting neurons and specialized brain parts.

• Messages interpreted in the spinal cord:

  • Decisions about responses can be made during thinking.

• Conscious Response:

  • Impulses sent along motor neurons to effectors.

• Automatic Actions:

  • Actions become automatic with repeated pathways (e.g., musical instruments, sports).

Reflex Arcs

• Reflex Action:

  • Detects stimulus via receptors.

  • Message sent via sensory neuron -> interneuron (spinal cord) -> motor neuron -> effector.

  • Bypasses the brain.

• Sense Organs and Stimuli Detection:

  • Sight: Eye; Stimulus: Light; Receptors: Rods and cones (Photoreceptors)

  • Hearing: Ear; Stimulus: Sound; Receptors: Hairs in cochlea (Mechanoreceptors)

  • Touch: Skin; Stimuli: Heat, cold, pressure, movement; Receptors: Separate types (Thermoreceptors, Mechanoreceptors)

  • Taste: Tongue; Stimuli: Chemicals; Receptors: Tastebuds (Chemoreceptors)

  • Smell: Nose; Stimuli: Chemicals; Receptors: Olfactory nerves (Chemoreceptors)

Endocrine System

• Composed of endocrine glands that secrete hormones into the bloodstream.

• Hormones act as chemical messengers transporting responses to target cells throughout the circulatory system.

Hormones and Their Functions

• Hormones:

  • Adrenaline (Adrenal): Increases blood pressure, heart rate, metabolism in stress.

  • Aldosterone (Adrenal): Regulates salt and water balance.

  • Cortisol (Adrenal): Stress response.

  • DHEA (Adrenal): Aids in body odor and hair growth during puberty.

  • Estrogen (Ovary): Regulates menstrual cycle, pregnancy maintenance, and female characteristics.

  • FSH (Pituitary): Produces eggs and sperm.

  • LH (Pituitary): Controls estrogen/testosterone production and ovulation.

  • Oxytocin (Pituitary): Lactation, childbirth, mother-child bonding.

  • Prolactin (Pituitary): Promotes breast milk production.

  • Glucagon (Pancreas): Increases blood glucose levels.

  • Insulin (Pancreas): Decreases blood glucose levels.

  • Melatonin (Pineal): Regulates sleep/wake cycles.

  • Parathyroid Hormone (Parathyroid): Controls calcium levels.

  • Progesterone (Ovary): Prepares body for pregnancy.

  • Testosterone (Ovary, Testes, Adrenal): Contributes to sex drive/body density & male characteristics.

  • Thyroid Hormone: Controls metabolic rate and energy levels.

Hormonal Diseases

• Hyperthyroidism: Excess thyroid hormone.

  • Symptoms: Fatigue, nervousness, weight loss, diarrhea, heat intolerance, fast heart rate, sleep issues.

• Hypothyroidism: Insufficient thyroid hormone.

  • Symptoms: Fatigue, weight gain, constipation, cold intolerance, dry skin/hair, slow heart rate, irregular periods, fertility issues.

• Cushing Syndrome: High cortisol levels.

  • Symptoms: Weight gain, facial/abdominal fatty deposits, stretch marks, slow healing, thin skin, irregular periods, decreased sex drive.

• Addison Disease: Low cortisol/aldosterone levels.

  • Symptoms: Fatigue, weight loss, abdominal pain, low blood sugar, nausea, diarrhea, irritability, salt cravings, irregular periods.

• Diabetes: Improper blood sugar regulation; high glucose levels in blood.

  • Symptoms: Fatigue, weight loss, increased hunger/thirst, frequent urination, irritability, infections.

Cellular Respiration

• Process of breaking down glucose for energy;

  • Waste product produced: Carbon dioxide.

• Equation: Glucose + Oxygen → Carbon Dioxide + Water + Energy.

Circulatory System Functions

• Transports oxygen/nutrients to cells; removes wastes (CO2).

• Blood Cell Transport:

  • Arteries: Carry blood away from the heart.

  • Capillaries: Site for material exchange with cells.

  • Veins: Return blood to the heart.

Respiratory System and Circulatory System Interaction

• Alveoli surrounded by capillaries containing red blood cells.

• Haemoglobin: Binds with oxygen to form oxyhaemoglobin.

Nutrients for Survival

• Essential for energy, cell functioning, growth, and repair.

• Five Main Nutrient Groups:

  • Carbohydrates: Immediate energy.

  • Proteins: Bodybuilding and repair.

  • Lipids: Reserve energy.

  • Vitamins: Maintain health and aid reactions; no caloric value.

  • Minerals: Inorganic; essential for health.

Digestive System Overview

• Process: Ingests, digests, and egests food.

• Begins in the mouth:

  • Salivary glands secrete enzymes (e.g., amylases) for chemical digestion of carbohydrates.

  • Teeth facilitate mechanical digestion; tongue forms bolus.