Biology Chapter: Integumentary System and Senses

Integumentary and Sensation

• Skin has three layers: epidermis (protective barrier), dermis (contains blood vessels, nerves, and glands), and hypodermis (stores fat for insulation).
• Melanin absorbs harmful UV radiation.
• Sebaceous glands produce sebum for moisturizing.
• Sweat glands regulate body temperature.

Eye Structures and Functions

• Cornea refracts light for focusing.
• Retina converts light signals.
• Iris controls the amount of light entering the eye.
• Optic nerve transmits visual information to the brain.

Hearing Process

• Outer ear captures sound waves.
• Middle ear amplifies sound via ossicles.
• Inner ear converts sound to neural signals (cochlea is key).

Hair and Nails

• Hair is composed of keratin, growing from follicles in the dermis.
• Nails are made of keratin, protecting fingertips and toenails.

Gl System

• Digestion is mechanical (physical breakdown, e.g., chewing) and chemical (enzymatic breakdown, e.g., amylase breaks down carbohydrates).
• Mouth initiates digestion.
• Esophagus transports food.
• Stomach performs acidic breakdown.
• Small intestine absorbs nutrients.
• Large intestine absorbs water and forms stool.
• Liver produces bile for fat digestion and regulates glucose.
• Pancreas regulates glucose via glycogen storage.

Endocrine System

• Hormonal regulation maintains balance (e.g., insulin).
• Positive feedback amplifies changes (e.g., oxytocin in childbirth).
• Hypothalamus controls the pituitary gland.
• Pituitary gland releases hormones (e.g., growth hormone).
• Thyroid regulates metabolism.
• Adrenal glands produce epinephrine and cortisol.
• ADH (antidiuretic hormone) regulates water retention in the posterior pituitary.
• Oxytocin stimulates uterine contractions and milk ejection.
• Thyroid produces T3 and T4 regulating metabolism.
• Parathyroid regulates calcium via PTH.
• Insulin lowers blood sugar; glucagon raises it.
• Epinephrine affects heart rate, blood pressure, and energy.
• Circadian rhythm hormones (e.g., melatonin) are regulated by the pineal gland.
• Aldosterone regulates sodium and potassium levels (secreted by adrenal cortex).

Lymphatic and Immune System

• Immune cells (e.g., neutrophils, lymphocytes, T-cells, B-cells) combat infections.
• Antigens trigger immune responses.
• Lymph nodes filter pathogens.
• Lymphatic fluid transports immune cells.
• Inflammation includes redness, heat, swelling, and pain, for protection and healing.
• Passive immunity is from another source (e.g., breastfeeding); active from infection or vaccine.

Renal System

• Nephrons filter blood, regulate electrolytes.
• Renal cortex/medulla filter and concentrate urine.
• Blood filtration occurs in the glomerulus; urine forms through reabsorption and secretion.
• Micturition reflex coordinates bladder contraction and urethral sphincter relaxation.
• ADH retains water, increasing blood volume.
• Aldosterone promotes sodium reabsorption, raising blood pressure.

Nervous System

• Somatic nervous system controls voluntary actions (e.g., skeletal muscles).
• Autonomic nervous system controls involuntary actions (e.g., heart rate).
• Central nervous system (CNS) is the brain and spinal cord.
• Peripheral nervous system (PNS) consists of nerves outside the CNS.
• Sensory neurons (afferent) transmit information to the CNS.
• Motor neurons (efferent) transmit information from the CNS.
• Neurons have dendrites, cell bodies, and axons.
• Cranial nerves originate in the brain; spinal nerves in the spinal cord.
• Chemoreceptors detect chemicals, osmoreceptors monitor osmotic pressure, nociceptors detect pain, thermoreceptors detect temperature.
• Different brain lobes serve specific functions (e.g., frontal for decision-making, parietal for sensory input).
• Sympathetic ("fight or flight") and parasympathetic ("rest and digest") are autonomic branches.
• Cerebrospinal fluid protects, nourishes the brain/spinal cord.
• Myelin insulates axons speeding up nerve impulses.

Reproductive System

• Uterus supports fetal development.
• Uterine tubes transport ova, site of fertilization.
• Mammary glands produce milk, regulated by prolactin and oxytocin.
• Male reproductive system includes testes, vas deferens, prostate, and penis.
• Shared urethra for semen and urine passage.

Test your knowledge on the integumentary system and sensory functions including skin layers, eye structures, and hearing processes. Understand how these components work together to protect the body and process sensory information. This quiz covers key concepts relevant to biology studies.