HESI A2 Anatomy and Physiology: Comprehensive Study Notes

Histology and Tissue Overview

• histology = the study of tissues
• tissue = a group of cells that act together to perform a specific function
• fundamental tissues = Epithelial, Connective, Muscle, Nerve (Elephants Can Make News) mnemonic
• function of epithelial cells = cover, line, and protect the body and the internal organs
• function of connective tissue = framework of the body; provides support and structure to organs
• neuroglia = the neurons and connective tissue cells that compose nerve tissue
• muscle tissue = ability to contract and shorten
• muscle tissue classification = Voluntary (skeletal muscles) and Involuntary (smooth & cardiac)
• meiosis = the cell division that takes place in the gonads, i.e. the ovaries and testes
• skin has two layers = Epidermis and Dermis
• epidermis = outermost protective layer of dead keratinized epithelial cells
• dermis = underlying layer of connective tissue with blood vessels, nerve endings, and associated skin tissues
• layers of the epidermis = Corneum, Lucidum, Granulosum, Germinativum (basale & spinosum)
  • Mnemonic: Candy Lions Growl Great
• melanin function = protects against radiation from the Sun
• dermis composition = fibrous connective tissue with nerve endings, blood vessels, sensory nerve endings, hair follicles, and glands
• sweat glands = two types: eccrine (often misspelled ecrine) & apocrine
• eccrine sweat glands produce = sweat; regulate body temperature
• apocrine sweat glands produce = secretions containing bits of cytoplasm from cells, attracting bacteria that produce body odor
• sebaceous glands secrete = sebum through hair follicles; lubricates the skin and prevents drying
• secretion that produces oil = holocrine secretion
• sebaceous glands during adolescence = prone to becoming clogged and attracting bacteria
• keratin = the protein that composes hair and skin
• body framework = bone, cartilage, ligaments & joints
• functions of the skeletal system = support, movement, blood cell formation, protection of internal organs, detoxification, muscle attachment, mineral storage
• bone classification by shape = long, short, flat, irregular, sesamoid
• osteoblasts = the cells that compose compact bone
• osteocytes = osteoblasts when embedded in dense bone matrix; they stop dividing but continue to maintain body tissues
• axial skeleton bones = 28 bones of the skull (14 facial, 14 cranium)
• facial skeleton bones = 2 nasal, 2 maxillary, 2 zygomatic, 1 mandible, 2 palatine, 1 vomer, 2 lacrimal, 2 inferior nasal
• cranium bones = occipital, frontal, ethmoid, sphenoid; paired parietal, temporal
• ossicles (ear bones) = malleus, incus, stapes
• skeletal column bones = 33
• cervical vertebrae = 7
• thoracic vertebrae = 12
• lumbar vertebrae = 5
• sacral vertebrae = 5
• coccygeal vertebrae = 1
• final part of the axial skeleton = the thorax comprising the sternum and 12 pairs of ribs
• appendicular skeleton = the bones of the girdle and limbs
• upper appendicular skeleton = pectoral & shoulder girdle; clavicle; scapula; upper extremities
• arm bones = humerus, radius, ulna, carpals, metacarpals, phalanges
• os coxae = fused ilium, ischium, pubis
• lower extremities = femur, tibia, fibula, tarsals, metatarsals, phalanges

Muscular System and Movement

• how muscles make movement = contraction in response to nervous stimulation
• muscle fiber contraction = myosin & actin filaments slide together within sarcomeres
• muscle cells = myofibrils made up of sarcomeres
• requirements for muscle contraction = calcium and ATP
• nervous stimulation effect = release of calcium ions from the sarcoplasmic reticulum
• role of calcium in contraction = binds to inhibitory proteins on actin filaments, moving them aside; forms cross-bridges between actin and myosin
• skeletal muscles = voluntary; under conscious control
• how skeletal muscles work = in pairs: the prime mover and the antagonist
• prime mover function = the muscle that executes a given movement
• antagonist function = the muscles that execute the opposite movement of the prime mover
• synergists = muscles that work together with the prime mover
• muscle classification = according to movements they elicit; two classifications: flexors and extensors
• flexors = reduce the angle at the joint
• extensors = increase the angle at the joint
• abductor = draw a limb away from the midline
• adductor = return the limb back toward the body

Nervous System and Neurons

• nervous system composition = the brain, spinal cord & nerves
• functional units of the nervous system = the neuron
• main parts of the neuron = cell body, axon, dendrites
• dendrites = transmit impulses toward the cell body
• axon = transmits impulses away from the cell body
• CNS = Central Nervous System; PNS = Peripheral Nervous System
• PNS composition = all the nerves that transmit information to and from the CNS
• sensory (afferent) neurons = transmit information to and from the CNS
• motor (efferent) neurons = transmit nerve impulses away from the CNS toward effector organs (muscles, glands, digestive organs)
• 3 major parts of the brain = Cerebrum, Cerebellum, Medulla Oblongata
• cerebrum = function in movement & sensory input
• cerebellum = muscular coordination
• medulla oblongata = controls vital functions such as respiration and heart rate
• spinal cord length = 18 inches
• spinal cord nerve exits = 31 pairs
• simple (spinal) reflexes = nerve impulses travel through the spinal cord only and do not reach the brain

Endocrine System and Hormones

• endocrine system function = assists the nervous system in maintaining homeostasis and plays important roles in sexual maturation
• where the endocrine and nervous systems meet = hypothalamus and pituitary gland
• hypothalamus governs = the pituitary gland and is controlled by hormone feedback in the blood
• which system has longer-lasting effects = endocrine system
• hormones = chemical messengers that control growth, differentiation, and metabolism of cells
• two major hormone groups = steroid and nonsteroid
• steroid hormones = enter the cell and have a direct effect on the DNA of the nucleus
• nonsteroid hormones = serve as protein hormones; act on cell surface through second messenger
• usual second messenger for protein hormones = AMP (adenosine monophosphate) or cAMP in common texts; here noted as AMP
• how hormones affect cell activity = alters the rate of protein synthesis

The Pituitary and Master Gland

• pituitary gland = considered the master gland
• location = attached to the hypothalamus by a stalk called the infundibulum
• two major portions = Anterior lobe (adenohypophysis) and Posterior lobe (neurohypophysis)
• why adenohypophysis called tropic = hormones act mainly on other endocrine glands
• tropic hormones = STH, GH, ACTH, TSH, FSH, LH
• STH or GH = Growth Hormone
• ACTH = Adrenocorticotropic hormone
• TSH = Thyroid-stimulating hormone
• FSH = Follicle-stimulating hormone
• LH = Luteinizing hormone
• hormones released from the posterior pituitary = Oxytocin (labor hormone) and ADH (Antidiuretic hormone)
• other important endocrine glands include = Thyroid, Parathyroid, Adrenals, Pancreas, Gonads (ovaries & testes)
• where the endocrine and nervous systems meet = the hypothalamus and pituitary
• which system has long-lasting effects = endocrine system
• how hypothalamus governs the pituitary = via feedback from hormones in the blood; infundibulum connects hypothalamus and pituitary
• summary of tropic hormones = regulate other glands; STH GH, ACTH, TSH, FSH, LH
• summary of posterior pituitary hormones = Oxytocin and ADH

Quick Reference: Key Terms and Concepts

• Histology, tissue, epithelial, connective, muscle, nerve
• Epithelial functions, dermis vs epidermis, melanin, keratin
• Skin glands: eccrine, apocrine, sebaceous; holocrine secretion
• Skeleton: axial vs appendicular; skull counts; facial vs cranium bones; ossicles; vertebral counts
• Muscle physiology: sarcomere, calcium role, ATP, cross-bridges, prime mover, antagonist, synergists
• Nervous system: neurons, dendrites, axons, CNS vs PNS, afferent vs efferent
• Brain anatomy: cerebrum, cerebellum, medulla oblongata
• Spinal reflexes and autonomic connections
• Endocrine vs nervous system integration, hypothalamus pituitary axis, tropic hormones, posterior pituitary hormones

Key LaTeX style references used in this set:

• Numbered counts and measurements expressed in math mode: $7, 12, 5, 33, 28, 18, 31, 12, 14, 14, 12, 2, 1, 3, 4, 9, 15, 24, 36$ (examples of how counts could be formatted; adapt as needed for specific items)
• Hormone acronyms and equations use standard forms, e.g., $AMP$ as a second messenger in the nonsteroid hormone pathway
• Major organ and bone groupings are described with plain numbers where appropriate, e.g., $28$ skull bones, $14$ facial bones, $14$ cranium bones, $33$ vertebrae in the skeletal column, $31$ spinal nerves pairs, etc.