HESI A2 Anatomy & Physiology flashcards
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How to describe any location on the human body
- In anatomy, whose right and left do directional terms describe?
- The subject's own right and left, not the viewer's as they face the subject.
- Which body plane divides the body into front and back parts?
- The frontal (coronal) plane. A sagittal plane makes right and left parts; a transverse plane makes upper and lower parts.
- Is the elbow proximal or distal to the wrist, and why?
- Proximal. It is closer to where the arm attaches to the trunk.
- A person lies face up. Which side of the wrist is still anterior?
- The palm side. Terms are always used as if the body were in anatomical position, however it actually lies.
- Which structure separates the thoracic cavity from the abdominopelvic cavity?
- The diaphragm, which forms the floor of the thoracic cavity.
- Which serous membrane layer covers the organ, and which lines the cavity wall?
- The visceral layer covers the organ; the parietal layer lines the cavity wall. Fluid between them reduces friction.
The four tissue types, what they do, and where to find them
- What are the four primary tissue types?
- Epithelial, connective, muscle and nervous tissue.
- Why does epithelium get nutrients by diffusion?
- Epithelium has no blood vessels (it is avascular). Nutrients diffuse in from the connective tissue below it.
- Which muscle tissue is striated, involuntary and joined by intercalated discs?
- Cardiac muscle, found in the heart wall.
- Is blood epithelial or connective tissue?
- Connective tissue. Blood is a fluid connective tissue, because its matrix is liquid.
- Why does cartilage heal slowly?
- Cartilage has no blood vessels, so nutrients must diffuse through its matrix. Bone, by contrast, has a rich blood supply.
- Which epithelium lines the lung alveoli and capillary walls, and why?
- Simple squamous epithelium. It is thin, which allows fast diffusion and filtration.
How one cell becomes two, or four
- In which phase is DNA copied, and what does each chromosome look like afterward?
- S phase of interphase. Each chromosome becomes two sister chromatids joined at a centromere.
- Give the order of mitosis, and name the step that follows.
- Prophase, metaphase, anaphase, telophase. Cytokinesis then divides the cytoplasm.
- How do the cells made by mitosis and by meiosis compare?
- Mitosis makes 2 genetically identical diploid cells. Meiosis makes 4 genetically different haploid cells.
- What does meiosis I separate?
- Homologous chromosomes. Sister chromatids stay joined until meiosis II.
- When does crossing over happen, and why does it matter?
- In prophase I of meiosis. Nonsister chromatids swap segments, which helps make the four cells genetically different.
- A cell with 2n = 8 finishes meiosis. Chromosomes per new cell?
- 4. Meiosis halves the chromosome number, so each new cell is haploid.
How your skin is layered and what each layer does
- Which epidermal layer is deepest, and what happens there?
- The stratum basale. Its cells divide, and new keratinocytes are pushed toward the surface.
- Does the epidermis contain blood vessels?
- No. Blood vessels are in the dermis and hypodermis.
- What do dermal arterioles do when the body is too hot, and why?
- They dilate. More warm blood flows near the surface and loses heat, and sweat also increases.
- A person's skin looks pale in the cold. What did the dermal arterioles do?
- They constricted, keeping warm blood in the core so internal organs stay warm.
- Why can a third-degree burn hurt less than a second-degree burn?
- It destroys nerve endings. Less pain does not mean a shallower burn.
- How does sunlight help the body absorb calcium and phosphorus?
- UV light lets the epidermis make vitamin D, which the liver and kidneys activate. Vitamin D is needed to absorb them.
How bones are built, remodeled, and joined
- How many bones does an adult skeleton have, and how are they divided?
- 206 bones: 80 in the axial skeleton and 126 in the appendicular skeleton.
- Which bone cells build bone, and which break it down?
- Osteoblasts build bone. Osteoclasts resorb (break down) bone. Osteocytes maintain the matrix.
- What happens to blood calcium if osteoclasts become much less active?
- Less calcium leaves bone, so blood calcium tends to fall. PTH normally raises it by increasing osteoclast activity.
- Which hormone lowers blood calcium, and which gland makes it?
- Calcitonin, from the thyroid. It inhibits osteoclasts. PTH from the parathyroid glands raises blood calcium.
- Is the sacrum axial or appendicular?
- Axial. It is part of the vertebral column even though it sits in the pelvis.
- How do ligaments and tendons differ?
- Ligaments join bone to bone. Tendons attach muscle to bone.
How muscles contract, from nerve signal to sliding filaments
- Which muscle type is striated but involuntary?
- Cardiac muscle. Striated does not mean voluntary.
- What does calcium bind to in a muscle fiber, and what does that uncover?
- Calcium binds troponin, which moves tropomyosin off the binding sites on actin.
- Why is a muscle with no ATP stiff instead of relaxed?
- Myosin needs ATP to let go of actin. Without it, cross-bridges stay locked, as in rigor mortis.
- During contraction, do the actin and myosin filaments get shorter?
- No. They slide past each other. The sarcomere shortens as Z-discs move closer, while the A band stays the same width.
- What does acetylcholinesterase do at the neuromuscular junction?
- It breaks down ACh in the synaptic cleft so the signal does not keep firing.
- When you straighten your knee, which muscles are agonists and which are antagonists?
- The quadriceps are agonists and the hamstrings are antagonists. The roles switch when you bend the knee.
How the nervous system sends and sorts signals
- Which ion movement causes depolarization, and which causes repolarization?
- Na+ rushing into the neuron depolarizes it. K+ flowing out repolarizes it.
- Does a stronger stimulus produce a bigger action potential?
- No. Action potentials are all-or-none: they fire fully if threshold is reached, or not at all.
- What does calcium do at the axon terminal?
- Ca2+ entering the terminal makes vesicles release neurotransmitter into the synaptic cleft.
- Which autonomic division slows the heart and favors digestion?
- The parasympathetic division (rest-and-digest). The sympathetic division raises heart rate and turns digestion down.
- Which brain region would you suspect in clumsy, uncoordinated walking?
- The cerebellum. It compares motor commands with feedback and corrects them to keep movement coordinated.
- What are the five parts of a reflex arc, in order?
- Receptor, sensory neuron, spinal cord (processing), motor neuron, effector.
How hormones and negative feedback keep blood glucose steady
- Which pancreatic hormone raises blood glucose, and which islet cells release it?
- Glucagon, from alpha cells. It makes the liver break glycogen into glucose and build new glucose.
- How does insulin lower blood glucose?
- It helps cells, mainly muscle and fat, take glucose out of the blood. The liver also stores extra glucose as glycogen.
- T3 and T4 levels are rising. What happens to TSH, and why?
- TSH secretion decreases. Rising T3 and T4 slow the chain, which is negative feedback.
- Which hormone shows positive feedback during labor?
- Oxytocin. Contractions stretch the cervix, which triggers release of more oxytocin.
- Where are ADH and oxytocin made, and where are they released?
- They are made in the hypothalamus. The posterior pituitary stores and releases them.
- Is the pancreas an exocrine or an endocrine gland?
- Both. Digestive juice leaves through ducts; insulin and glucagon go into the blood.
How blood flows through the heart
- Do arteries always carry oxygen-rich blood?
- No. Arteries carry blood away from the heart. The pulmonary arteries carry oxygen-poor blood to the lungs.
- In order, which four valves does blood cross as it passes through the heart?
- Tricuspid, pulmonary, mitral, then aortic.
- Why is the left ventricle wall thicker than the right?
- It must generate far more pressure to push blood through the whole body, not just the lungs.
- Where do the pulmonary veins empty, and what blood do they carry?
- They empty into the left atrium and carry oxygen-rich blood back from the lungs.
- What does the AV node do to the heart's electrical signal, and why?
- It holds the signal about a tenth of a second so the atria finish emptying into the ventricles first.
- What causes the first heart sound, "lub"?
- The AV valves closing as the ventricles start to contract. The second sound, "dub," is the semilunar valves closing.
How the body defends itself: innate and adaptive immunity
- How do innate and adaptive immunity differ in speed and specificity?
- Innate is fast and nonspecific. Adaptive is slower on first exposure but specific and has memory.
- Which cells secrete antibodies?
- Plasma cells, which come from activated B cells. T cells do not secrete antibodies.
- Is a vaccine active or passive immunity?
- Artificially acquired active immunity. Your own body makes the antibodies and memory cells.
- What causes the swelling during inflammation?
- Histamine from mast cells makes capillaries leaky, so fluid seeps into the tissue.
- What happens when the body meets the same pathogen a second time?
- Memory B and T cells give a secondary response that is faster and stronger, often before symptoms appear.
- Where do B cells mature, and where do T cells mature?
- B cells mature in the bone marrow. T cells mature in the thymus.
How air reaches the alveoli and how oxygen and CO2 trade places
- Does gas exchange happen in the trachea, the bronchi, or the alveoli?
- The alveoli, in the respiratory zone. The conducting zone only moves, cleans, warms and humidifies air.
- What is the main everyday signal to breathe faster and deeper?
- Rising blood CO2, which lowers pH. Falling oxygen becomes a strong signal only when it gets very low.
- Why does air flow into the lungs during inhalation?
- The diaphragm contracts, chest volume grows, alveolar pressure drops below atmospheric pressure, and air flows in (Boyle's law).
- Which way does carbon dioxide move in the lungs, and why?
- From blood (about 45 mm Hg) into the alveoli (about 40 mm Hg), down its partial pressure gradient.
- How is most carbon dioxide carried in the blood?
- As bicarbonate, about 70 percent. About 20 percent binds hemoglobin and 7 to 10 percent is dissolved.
- What does surfactant do in the alveoli?
- It lowers surface tension in the watery film lining each alveolus. Without it, alveoli would collapse when you breathe out.
How food is broken down and absorbed, from mouth to colon
- Where does protein digestion begin, and which enzyme starts it?
- In the stomach, with pepsin. Pepsin is activated from pepsinogen by hydrochloric acid.
- Does bile chemically break down fat?
- No. Bile salts emulsify fat into tiny droplets so lipase has more surface. Pancreatic lipase does the chemical splitting.
- Which organ makes bile, and which organ stores it?
- The liver makes bile. The gallbladder stores it, concentrates it, and releases it when fatty chyme arrives.
- Why does pancreatic juice contain bicarbonate?
- Bicarbonate neutralizes the acidic chyme that enters the duodenum from the stomach.
- How do long-chain fat products leave the villi differently from glucose?
- Fat products enter lacteals (lymphatic vessels). Glucose and amino acids enter the villus capillaries.
- What would happen to nutrient absorption if the villi were flattened?
- Absorption would drop. Folds, villi and microvilli give the small intestine its huge surface area for absorbing nutrients.
How the kidneys filter blood and make urine
- After urine leaves the collecting duct, what path does it take out of the body?
- Calyces, renal pelvis, ureter, urinary bladder, urethra, then outside the body.
- Which nephron part reabsorbs the most, and what does it reclaim almost completely?
- The proximal convoluted tubule. It reclaims nearly all glucose and amino acids, plus about 67 percent of filtered water and sodium.
- What happens to urine volume if ADH secretion stops?
- Less water is reabsorbed in the collecting duct, so a large volume of dilute urine results.
- What does aldosterone do to sodium and potassium?
- It increases sodium reabsorption, and water follows. It also increases potassium loss in urine.
- Why can glucose appear in urine in uncontrolled diabetes?
- Glucose transporters in the PCT have a top speed. Very high blood glucose overwhelms them, so glucose spills into urine.
- How do reabsorption and secretion differ?
- Reabsorption moves substances from the tubule back into the blood. Secretion moves them from the blood into the tubule.
How the male and female reproductive systems make gametes and new life
- Which testis cells make testosterone, and which support developing sperm?
- Leydig cells make testosterone, responding to LH. Sertoli cells support sperm development, responding to FSH.
- Where are sperm made, and where do they mature?
- They are made in the seminiferous tubules and mature in the epididymis.
- What triggers ovulation in a typical 28-day cycle?
- An LH surge around day 14, set off by very high estrogen from the dominant follicle.
- What does the corpus luteum secrete after ovulation, and why?
- Progesterone, which prepares the endometrium for implantation.
- What happens to the endometrium if no pregnancy occurs?
- The corpus luteum breaks down, progesterone falls, and the functional layer of the endometrium is shed (menses).
- Where does fertilization usually happen?
- In the uterine tube, most often the ampulla. It does not usually happen in the uterus or ovary.
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