Biology 3 Flashcards

Question

* Musculoskeletal System * Skeletal Muscle anatomy * Diagram the following: * fasciculi * muscle fibers * sarcolemma * myofibrils * sarcomeres * sarcoplasmic reticulum

Answer 1

* **All** erythrocytes and leukocytes are made in the red bone marrow via hematopoiesis * Yellow bone marrow is primarily adipose tissue and does **NOT** produce blood cells. * B lymphocytes mature in the bone marrow * T lymphocytes migrate to the **thymus** to mature.

Answer 2

1. Blood vessels closer to the surface of the skin **dilate** when heat needs to be **released** and **constrict** when heat needs to be **retained**. * Blushing is the result of the dilation of these superficial blood vessels. 2. Arrector pili muscles cause erection of hair follicles (resulting in “goose bumps”), that **traps an insulating layer of air next to the skin** * Contraction of Arrector pili muscles can also generate a small amount of heat. 3. Subcutaneous fat provides **insulation**. 4. Sweating, followed by evaporation of that sweat, **carries away a significant amount of heat** due to the high heat of vaporization of water and its high specific heat capacity.

Answer 3

* Physical support and movement * Protection of vital structures * Mineral storage * Regulation of: * blood mineral concentration * blood cell formation

Answer 4

* WHEN YOU SEE “CELL-MEDIATED” THINK: * **self-attack of diseased cells** * WHEN YOU SEE “HUMORAL” THINK: * **antibodies and primary/secondary response**

Answer 5

* Skeletal muscles store large amounts of glycogen * They also require a lot of oxygen and thus have ***THEIR OWN*** oxygen storage molecule, **_myoglobin_**. * Myoglobin is basically one subunit of a hemoglobin molecule, capable of holding one O2 molecule. * Mature (differentiated) skeletal muscle cells are frozen in G_o phase and do not divide (similar to neurons)

Answer 6

* Hydroxyapatite is an inorganic compound of: * calcium * phosphate * (PO₄^3-) * hydroxide * (OH^-) * Is the mineral matrix responsible for a bone’s **strength** * Is the form in which most all of the body’s **calcium is stored**.

Answer 7

* **“water absorption”** or **“vitamin absorption”** * In addition to absorbing vitamins from food, the large intestine also absorbs some vitamins produced by beneficial symbiotic E. Coli bacteria that live in the large intestine * (e.g., vitamin K, thiamin, riboflavin, and B12).

Answer 8

* Mutualism * Recall that mutualism is a form of symbiosis where **both participants benefit.** * The bacteria benefit by consuming the food in our intestines * We benefit because the bacteria produce vitamins that we absorb.

Answer 9

* **Colon** * rises upward along the right wall of the abdomen * **ascending** colon * traverses across the abdomen * **transverse** colon * descends along the left wall * **descending** colon * The final segment of the colon is somewhat twisted * **sigmoid** colon. * The primary function of the colon is: * the **absorption of water and vitamins.** * The colon contains resident commensal bacteria that secrete: * vitamin K * thiamin * riboflavin * vitamin B12 * **Rectum** * the *final segment of the large intestine* * Functions: * connects to the anus * stores feces.

Answer 10

* In response to low blood glucose levels alpha cells in the pancreas secrete glucagon. * Glucagon **stimulates glycogenolysis** in the liver—the breakdown of glycogen stored in the liver **to form free glucose** for release into the blood. * In contrast, high blood glucose levels stimulate beta cells in the pancreas to secrete insulin. * Insulin **stimulates glycogenesis** in the liver—the synthesis of glycogen for storage in the liver. * Insulin also stimulates the **uptake of glucose from the blood** into the cells. * Finally, the liver also makes glucose out of lactate, glycerol, amino acids, and some TCA cycle intermediates. * Liver producing new glucose=**GLUCONEOGENESIS**

Answer 11

* **Pepsin** catalyzes the hydrolysis of proteins. * The partially digested food mix, now referred to as chyme, passes through the **pyloric sphincter** and into the *upper portion of the small intestine* * called the **duodenum**. * The common bile duct and the pancreatic duct both dump into the duodenum. * As a result, the duodenum receives: * bile from the liver/gallbladder * a bicarbonate rich solution * six digestive enzymes from the pancreas * The chyme progresses through the small intestine to its middle section, * called the **jejunum**, * ...and then to the final section, * called the **ileum**. * There are **no distinct boundaries** marking these three sections * Most digestion occurs in the **duodenum** * most absorption (of food molecules, not water) occurs in the **jejunum** and **ileum**

Answer 12

* Antigen presentation * the process by which a cell that has engulfed an antigen or microbe, (via receptor-mediated endocytosis or phagocytosis) takes protein portions of that microbe or antigen and “presents” them on MHC (Major Histocompatability Complex) proteins embedded in its own cell membrane for other cells to “see.” * Macrophages, dendritic cells, and B-cells can all “present” antigens * (Note: Other cells types can also “present” to a small extent, but they do not play a major role in immune system function)

Answer 13

1. Long bones * (e.g., femur, humerus) 2. Short bones * (e.g., tarsals, carpals) 3. Flat bones * (i.e., skull, sternum) 4. Irregular bones * (e.g., hip, vertebrae)

Answer 14

* The non-specific attack of pathogens. * All forms of innate immunity are **present at birth** * NOT acquired in ***ANY WAY***

Answer 15

* **_Unitary (or single-unit) smooth muscle_** * is group of smooth muscle fibers that are innervated by a **single** nerve and contract **simultaneously** as a single group. * These are the ***most common*** smooth muscle unit * Are found in : * most organs * around most blood vessels * the digestive tract, etc. * **_Multi-unit smooth muscle_** * innervated by **multiple** nerves and does **not** act as a single unit. * This allows for **more precise control** * ****remember, however, that all smooth muscle is involuntary, so it is **not conscious control** * Multi-unit smooth muscle is quite rare. * It is found in some of the larger vessels such as: * the aorta * in the retina of the eye

Answer 16

* **Secrete HCl** (into gastric pits/stomach lumen). * HCl is responsible for the **extreme acidity** (pH = 2) of the stomach **and for the conversion of pepsinogen to pepsin**, the *ACTIVE FORM* of the enzyme.

Answer 17

* Around day 14 of the menstrual cycle high ***estrogen* levels stimulate** a rapid **increase** in ***luteinizing hormone (LH)***, a good example of a *_positive feedback_* mechanism. * This does not happen during other stages of the cycle where LH stimulates estrogen, and estrogen provides negative feedback to the hypothalamus inhibiting further LH secretion (i.e., classic negative feedback loop). * However, as mid-cycle approaches estrogen levels provide positive feedback to the hypothalamus, stimulating it to secrete more LH, which in turn stimulates the production of more estrogen. * This causes the “LH surge,” which results in ovulation.

Answer 18

* The lining cells of the stomach are protected by a **thick layer of mucus** secreted by the mucus cells that line the gastric pits (one of four cells found there)

Answer 19

* Trypsin and chymotrypsin * are both proteases. * Each enzyme cuts proteins at its own specific amino acid sequence. * Pancreatic amylase * catalyzes the hydrolysis of carbohydrates. * Lipase * catalyzes the hydrolysis of fats. * Ribonuclease * catalyze the hydrolysis of RNA * Deoxyribonuclease * catalyzes the hydrolysis of DNA * Some students find this (ribo & deoxyribonucleases) odd, thinking “Who eats DNA and RNA?” * While its true we don’t think of either as a food group, anything made of living cells—plant, fungi, animal, etc.--will contain both of these polynucleotides

Answer 20

* ***CALCITONIN*** * Remember that “calcitonin tones your bones.” * When blood levels are above normal calcitonin **inhibits osteoclast activity** * Osteoblast activity continues and thereby a net increase in bone structure results. * The calcium used by osteoblasts to build new bone matrix comes from the blood ∴ blood calcium levels **decrease** * ***PARATHYROID HORMONE (PTH)*** * Parathyroid hormone has the opposite effect * Parathyroid hormone stimulates osteoclast activity * resulting in the breakdown of bone matrix and **release of calcium into the blood** * As a result, **blood calcium levels rise** * The two hormones also have predictable impacts on the **absorption of calcium at the gut** and the **reabsorption of calcium in the kidney**

Answer 21

* **Myosin** filaments contain **bead-like heads** * also called arms or cross-bridges * The default, low-energy position for these heads is ***BENT*** * In between contractions, ATP hydrolysis (ATP ⇒ ADP + Pi) is used to provide the energy to straighten-out, or “**cock**”, these myosin heads into the high-energy, **straight position**. * **_Regardless of which position the myosin heads are in_** (straight or bent): * they are **attracted** to, and **bind readily** with, their neighboring actin filaments. * The only reason they are not bound **continuously** is a protein molecule called ***TROPOMYOSIN***, * which **covers the myosin binding site** on the actin filament. * Tropomyosin is “clamped” into position by another protein, * **troponin** * When calcium is released from the sarcoplasmic reticulum it **binds to troponin** * releasing the “clamp” and freeing the binding site. * Myosin will then immediately bind to actin. * Recall that the myosin heads are still in their high-energy, **straight** position. * After binding, the myosin heads release ADP and Pi * ATP is NOT hydrolyzed into ADP and Pi. * This already occurred as the heads were cocked into the straight position * The small amount of energy linked to this dissociation is **enough to “pull the trigger,”** allowing the heads to **relax** back to their **bent** position. * Because they are still bound, **they drag the actin filaments with them** * This is the "***POWER STROKE***" associated with contraction * After the power stroke, ATP binds to the myosin head again * facilitating its **release from the actin filament.** * Tropomyosin immediately **re-covers the myosin binding site**. * Finally, the attached ATP is hydrolyzed * providing the necessary energy to push the head back into the high-energy straight, or “**cocked**,” position.

Answer 22

* Digestion begins in the mouth * with salivary amylase * Digestion is complete **by the end of the small intestine.** * In the small Intestine: * Carbohydrates are broken down entirely to their monomers (e.g., glucose, fructose, etc.) **before absorption** * They enter the ***blood stream*** (NOT the lacteal) and * Travel to the ***liver*** via the hepatic portal vein.

Answer 23

* **Vas deferens** * is a duct that **connects each testicle with the urethra.** * Beginning at the **epididymis**, it leads up the inside of the scrotum, into the pelvic cavity, past the **seminal vesicles**, and **prostate gland**, and dumps into the **urethra** before the urethra enters the penis.

Answer 24

* Movement * support and stabilization * generation of heat * aide to circulation * maintenance of homeostasis.

Answer 25

* **Penis** * is the male copulatory organ. * It can also be thought of as playing a structural role in excretion and ejaculation because the urethra runs through it. * **Testicles** * serve the primary functions of *making, nurturing and storing sperm.* * **Scrotum** * is the thin sack of skin in which the testes are located. * The external location of the scrotum allows the testicles to exist at a temperature a few degrees lower than the normal human body temperature of 37°C. * The optimum temperature for spermatogenesis is 35°C. * Sperm cells are the male haploid gametes. * **Seminiferous Tubules (of the testes)** * Sperm cells are produced in the STs of the testes and move to the epididymis, where they are nurtured, fully matured, and stored until ejaculation

Answer 26

* **Dendritic cells** * are *_professional antigen-presenting cells._* * phagocytize pathogens and present those antigens on their surface * to **stimulate** other immune cells. * are white blood cells (leukocytes), **but are not lymphocytes.** * They can form from: * monocytes * which also differentiate into macrophages * independently in their own cell line * from a blood cell precursor. * There are three kinds of lymphocytes: 1. T cells, 2. B cells, and 3. natural killer cells * recognize infected or cancerous cells and release cytotoxic granules that destroy the cell. * **T cells** * are lymphocytes that mature in the thymus * participate in **cell-mediated** immunity. * **B-cells** * are lymphocytes that mature in the bone marrow and lymph tissues * Participate in **humoral** immunity. * B-cells produce antibodies, **T-cells do not.** * T-cells recognize and bind antigens via a “Tcell Receptor” (TCR) **not** found on B-cells. * **Plasma cells** * are formed when: * a B-cell binds its matching antigen and is * Are activated when: * with the help of helper T-cells (T helps B) * to undergo **mitosis**. * This mitosis produces mostly plasma cells making and secreting soluble **copies of that antibody.**

Answer 27

1. **Protect** the body from infection and disease 2. **destroy** pathogens invading the body.

Answer 28

* Characteristics * voluntary, striated, and multinucleate. * Attachments * Tendons attach muscle to bone * ligaments attach bone to bone * The joints formed by most muscles and bones in the human body are examples of hinges with a **poor** lever system that work at a mechanical **disadvantage**. * For example, for the biceps brachii, the resistance is six times farther from the fulcrum than the force * meaning the muscle must create a force equal to six times the weight of the object in the hand.

Answer 29

1. Hot flashes 2. Vaginal dryness 3. Atrophy of breast tissue * All of these are the result of **decreased estrogen and progesterone levels**

Answer 30

* All pancreatic secretions empty into the **upper end of the duodenum** * *Just before emptying into the duodenum,* the pancreatic duct is joined by the **bile duct.**

Answer 31

* Make and secrete mucus (into gastric pits, which lead to the stomach, lumen) * The secreted mucous is alkaline, thus **providing protection from corrosion** due to the extreme acidity of the stomach. * Stomach ulcers are from a lack of mucous neck cells * NOTE: “Goblet cells” are mucous-secreting cells found in the linings of the intestines and respiratory tract. * Don’t confuse them with mucous cells.

Answer 32

1. Mouth 2. Epiglottis 3. Stomach 4. Liver 5. Pancrease 6. Gallbladder 7. Small Intestine 8. Large Intestine

Answer 33

* During ejaculation, sperm leave the epididymis via the vas deferens. * The vas deferens arches back up into the pelvis and then back down toward the penis. * Along the way, the seminal vesicles, prostate gland and bulbourethral gland (a.k.a. Cowper’s gland) all secrete various lubricants and nutrients into the ejaculate. * The vas deferens empties into the urethra at the base of the urinary bladder. * The urethra then travels down the penis * SPLOOSH!

Answer 34

* Proteins in the stomach undergo ***HYDROLYSIS***, a reaction catalyzed by the enzyme ***PEPSIN*** * This enzyme begins as ***PEPSINOGEN***, which is an example of a zymogen * A zymogen is an **inactive** enzyme precursor

Answer 35

* Characteristics * involuntary, striated, one nucleus * Contraction * Cardiac muscle cells contain sarcomeres the same as those found in skeletal muscle and therefor use the same sliding filament mechanism outlined above.

Answer 36

1. Fibrous * (skull bones) 2. Cartilaginous * (ribs to sternum) 3. Synovial * (knee, elbow, etc.)

Answer 37

* Is both an **endocrine** ***_AND_*** an **exocrine** gland * exocrine * because of the digestive enzymes listed below * endocrine * because of insulin and glucagon * Secretes a **bicarbonate** rich solution, which **neutralizes the stomach acid,** decreasing the acidity of the intestine to pH = 6 * Secretes the following digestive enzymes: * trypsin * chymotrypsin * pancreatic amylase * lipase * ribonuclease * deoxyribonuclease

Answer 38

* **Stores and concentrates** bile, but does **NOT** produce bile. * Bile is produced ***IN THE LIVER*** * Bile *emulsifies fats* * i.e., separates fat molecules from each other * increasing the surface area available for enzymatic digestion * Bile emulsifies fats, **but it does not break any bonds** * therefore it is an example of **physical** rather than chemical digestion

Answer 39

* The acid in the stomach denatures proteins * Remember: acid is a protein denaturing agent

Answer 40

* the immune system’s first **exposure** and **reaction** to a pathogen

Answer 41

* Fix carbon. * The ability to “fix” carbon is the ability to **capture carbon dioxide** and **integrate that carbon into larger macromolecules.** * Plants, algae and some bacteria can do this, humans and animals generally cannot. * We must eat the carbon we need to build macromolecules

Answer 42

* The ***MAJORITY*** of all **digestion** and **absorption** occurs in the small intestine * digestion occurs primarily in the *duodenum* * absorption primarily in the *jejunum* and *ileum*

Answer 43

* **Vagina** * The vagina serves as: * the female copulatory organ * the birth canal * an exit route for menstrual fluid. * **Cervix** * is the conical-shaped bottom portion of the uterus that projects into the rear, upper wall of the vaginal canal. * It contains a small opening that allows for exchange of fluids, but **must dilate** significantly **during child birth** to allow for delivery. * **Uterus** * is an elastic, muscular pouch that : * receives a fertilized egg via implantation * **provides nourishment** for the developing fetus. * *Muscle contractions* of the uterine wall, stimulated by ***_oxytocin_***, facilitate the process of childbirth. * **Fallopian Tubes** * are ducts that utilize ciliated epithelium to transport the egg from the ovary to the uterus. * Fertilization usually occurs in one of the two fallopian tubes. * **Ovaries** * are the female gonads, homologous to the testes in males. * The ovaries develop and release ovum (i.e., eggs) on a regular 28-day cycle (on average). * They also function as **endocrine** glands * that secrete both **estrogen** and **progesterone**.

Answer 44

* Make and secrete **gastrin** * Gastrin is released **into the blood** (NOT into the gastric pits/stomach lumen) where it circulates back to the parietal and chief cells **stimulating them to release HCl** and **pepsinogen** * thus furthering enhancing digestion

Answer 45

* Either a vitamin deficiency or problems with water balanc * either **too little** water absorption (**diarrhea**), or * **too much** water absorption (**constipation**) * These are logical assumptions because the two primary functions of the large intestine are water absorption and vitamin absorption

Answer 46

* **Ectoderm** * epidermis, nails, tooth enamel, lens of the eye, pituitary gland, central, peripheral and autonomic nervous systems. * **Mesoderm** * dermis, muscle, bone, connective tissues, kidneys, genitalia and most internal organs *_EXCEPT the liver and pancreas._* * **Endoderm** * the entire digestive tract, thyroid, parathyroid, urinary bladder, the lining ONLY of the lungs, and the liver and pancreas.

Answer 47

_Villi_ * finger-like projections of the wall of the small intestine * The villi dramatically **increase the surface area** available for absorption * They are hollow and contain both blood vessels and a single lymphatic vessel called a **lacteal** **_LACTEAL_** **FATS** are absorbed into the **LYMPH** system via the lacteals **Carbohydrates** and **proteins** ****are **absorbed** into the **BLOOD** **_Microvilli_** * Each epithelial cell **lining a villus** contains fingerlike projections of the cell membrane called microvilli (villi within a villi) * To be clear, a villus is an undulation of the lining of the small intestine, while a microvillus is an undulation of the cell membrane of a single cell. **_Brush border_** *Microvilli+Mucus+Digestive Enzymes* is a name given to: * the **microvilli** and the collection of: * **digestive enzymes** * **mucus** ...intermingled **WITHIN** the microvilli

Answer 48

* Macrophages * engulf microbes and present antigens from those microbes on MHC proteins in their cell membranes to be recognized by B-cells and T-cells.

Answer 49

* Involves **B-cells** (i.e., B-lymphocytes)

Answer 50

* Think of the liver as the “metabolic brain” of the human body. * It regulates the blood concentrations of many different solutes * Plays key roles in the metabolism of: * proteins * fats * carbohydrates * detoxifies chemicals * recycles metabolites * manufactures several key biomolecules

Answer 51

* Shivering is an involuntary response to cold. * At sufficiently low temperatures a specific location within the hypothalamus receives signals from the skin and spinal cord. * The hypothalamus sends signals to core muscle groups to undergo rapid **contractions** that **generate heat.**

Answer 52

* The acrosome is a membrane-bound structure on the **tip of the head of each sperm**. * The acrosome contains hydrolytic enzymes that breakdown the **otherwise impenetrable** coating around the ovum

Answer 53

1. Mucous Neck Cells 2. Chief Cells 3. Parietal Cells 4. G-cells

Answer 54

* **Cleavage** * mitosis **without** change in size * **Morula** * 8-cell zygote * **Gastrulation** * at about week 2 cells migrate to form the three germ layers * **Neurulation** * ****at about week 3, the notochord forms from the mesoderm * Induces the overlying ectoderm to form the neural plate, * which becomes the neural tube * and eventually the spinal cord

Answer 55

Role of the **mouth** in digestion is: * to physically breakup food particles * via chewing * mix the food with **saliva** and the **alpha-amylase** enzyme it contains * Amylase begins carbohydrate digestion * The **lubricating** properties of saliva aide in ease of movement * There are also specific classes of ***antibodies** found in saliva.* The **pharynx** * ****ensures the bolus is delivered to the esophagus **without** entering the nasal cavities or the larynx ***NO DIGESTION** of any kind occurs here and **nothing** is added to the bolus* **epiglottis** * ****is an upward-oriented cartilaginous flap * folds down over the opening to the larynx during swallowing * to _prevent food from entering the larynx_. **esophagus** * ****utilizes **peristalsis** to *push the bolus down and into the stomach.* **Peristalsis** * ****the **rhythmic contraction of smooth muscle** in the wall of the gastrointestinal track that moves food forward. * Once again, **no digestion occurs** in the esophagus and **nothing** is added*

Answer 56

* If hormone levels go up unexpectedly, high levels could cause _unexpected menstruation_ if— ***AND ONLY IF***—that increase was **followed by a sudden decrease.** * It is the drop in hormone levels that causes menstruation. * Unexpected menstruation of this type can sometimes be seen in elderly women given estrogen/progesterone therapy for treatment of osteoporosis

Answer 57

* Smooth muscle is NOT arranged in sarcomeres * Smooth muscle does NOT contract via the same sliding filament mechanism described previously for skeletal and cardiac muscle. * It is similar—actin and myosin still slide past one another—but several different proteins are involved and the steps are NOT identical. * As an example, in skeletal muscle it is calcium binding to troponin that initiates contraction, but in smooth muscle **contraction is initiated by the calcium-dependent phosphorylation of the myosin head.** * Smooth muscle contraction is sometimes referred to as the “calcium-calmodulin cascade"

Answer 58

* It's its own thing, completely **separate*** * from the rest of the body* A **CONNECTIVE** tissue composed mostly of **COLLAGEN** ***_Experiences NO:_*** * ***PERFUSION*** * *Perfusion=* * *the process of a body delivering blood to a capillary bed in its biological tissue (see pic)* * ***INNERVATION*** * *Innervation= to arouse or stimulate (a nerve or an organ) to activity*

Answer 59

1. Physical Digestion * = chewing (mastication) * churning in stomach * breaking of food into smaller pieces * including emulsification of fats by bile 2. Chemical Digestion * = all breakdown of food that involves the **breaking of bonds** through the use of **digestive enzymes**

Answer 60

1. ***_Produces_*** Bile * which is then **stored** and **concentrated** in gall bladder 2. Filters the blood * to remove toxins, drugs, metabolites, bacteria, etc. 3. Produces blood plasma proteins, including: * albumin * prothrombin * fibrinogen 4. Regulates amino acid levels in the blood. 5. **Produces** cholesterol and lipoproteins and **packages** them for transport * (LDL, HDL, etc.)

Answer 61

1. Osteo**cytes** *("-Cyte"* * **Mature** bone cells surrounded by a mineral matrix 2. Osteo**clasts** * Bone cells that **break down** *("-Clast")* and **resorb** bone matrix * ...releasing the component minerals **(Ca²⁺ and P)** back into the blood. 3. Osteo**blasts** *("-blast"=IMMATURE cell)* * Immature bone cells that secrete collagen, organic compounds, and minerals * **forming** a bone matrix around themselves. * Once they are completely enclosed by matrix, they differentiate into osteocytes.

Answer 62

* B-cells that bind their specific antigen engulf it via receptor-mediated endocytosis and present a portion on MCH proteins in their cell membranes. * Helper T-cells recognize and **bind** this antigen * which causes the helper T-cell to release chemicals that stimulate other B and T cells and—most importantly—**stimulates the B-cell that presented it with the antigen to divide into** * **** a plasma cell, and * a memory B cell * In other words, it is through *antigen presentation* that a Helper T-cell **“helps” (i.e., activates) a B-cell** to perform its function. * A B-cell can either: * bind to a free-floating antigen, or * it may have an antigen “presented” to it by a **macrophage**

Answer 63

* **Memory B cells** * **** Allow the immune system to mount a more efficient secondary immune response if there is a later infection by the same pathogen

Answer 64

* Two epiphyses (bulbous ends) cushioned by cartilage * the ends are filled with spongy bone * the shaft in between is made of compact bone * the center is a hollow cavity * filled with yellow bone marrow

Answer 65

* All of the cells/fibers in a skeletal muscle ***DO NOT*** fire simultaneously during a contraction. * A **group** of muscle cells innervated by a **single** motor neuron is called a “motor unit” . * Motor units come in all different sizes from large to small.

Answer 66

**_A band_** * is the length of the **myosin** filaments * The length of the myosin filaments **DOES NOT CHANGE** during contraction* **_I band_** * is the distance between the **ends** of the myosin filaments * It is also the **lightest** band when viewed under a microscope * because only the **thin** actin filaments are present in this region *The I band will **SHORTEN** during a contraction.* **_H zone_** * is the distance between the ends of the actin filaments. * The H zone **SHORTENS** during a contraction* **_Z lines (a.k.a. Z discs)_** * are zigzag lines that define the ***edges** of each* **INDIVIDUAL sarcomere unit** The _actin filaments are anchored here_ by the protein ***CONNECTIN*** ...and stretch out in **both** directions. * During a contraction the distance between Z lines* **DECREASES** * (since the* **SARCOMERE SHORTENS!**) _**M** **line**_ * is the **VERY *CENTER* OF THE MYOSIN FILAMENTS** The distance between the _M lines of **NEIGHBORING** sarcomeres_ will ***DECREASE*** during a contraction (again, because the **SARCOMERE** is **SHORTENING**)

Answer 67

* If no ATP is present * the myosin heads cannot detach from actin and the muscle will be **stuck in a contracted position** called “rigor.” * This is what occurs during “rigor mortis” * If no Ca2+ is present * we do NOT get rigor, but the **inability to contract** (a.k.a., “flaccidity”)

Answer 68

* Delicate movements = **very small** motor units * Gross movements = **larger** motor units * The strength of a given contraction depends on: 1. number of motor units being used 2. size of the motor units being used 3. frequency of action potentials * (i.e., stimulation)

Answer 69

* Characteristics * involuntary, non-striated, one nucleus * Smooth muscle is what **controls the gut, viscera, blood vessels, etc.**

Answer 70

* The breakdown of all nutrient macromolecules into their monomers is accomplished via **hydrolysis**

Answer 71

* Saliva provides lubrication & the first example of a digestive enzyme * **Chemical** digestion of ***Carbohydrates only*** * via α-amylase

Answer 72

* High concentration of B- and T-lymphocytes * **Filters blood** for pathogens * Other Lymphatic Tissues: * Lymph tissue similar to the contents of a lymph node is spread throughout the body, being particularly common in the respiratory and gastrointestinal tracks.

Answer 73

* These cells are **antigen presentation experts** * They are specialized to do so efficiently and are found in the highest concentration *near membranes* (such as the skin) *that interface with the external environment* * *--*where they are most likely to **encounter antigens**

Answer 74

* To have menstruation, or the sloughing off of the uterine lining, we must first have a **buildup of that lining.** * * Build-up and maintenance of the uterine lining is one of the normal functions associated with estrogen/progesterone * ***Do NOT confuse menstruation with ovulation.*** * Ovulation requires a **surge** in hormone levels. * Menstruation requires a **chronic** decline. * Persistent low levels of estrogen/progesterone **lead to the symptoms of menopause**

Answer 75

Includes all immune responses that are NOT specific to one particular virus, bacteria, pathogen, etc. * skin * stomach acid * enzymes in the mucus and saliva * digestive enzyme, * blood chemicals * fevers * inflammation * non-specific phagocytosis

Answer 76

**BEGINS** in the **stomach** Is **COMPLETE** by the end of the **small intestine** _BEFORE BEING ABSORBED:_ Proteins are **broken down** to small peptides and amino acids They enter the **bloodstream** (NOT the lacteal) and travel to the **liver**

Answer 77

Sperm are the male **GAMETES** * **Plural** form: * "**spermatozoa"** * **Singular** form: * **"spermatozoon"** (Not a mix up. Thats really it) **_Produced_:** * by the **TESTICLES** * in the **ST's** _**Stored** and **nurtured:**_ * in the **EPIDIDYMIS** They are a **single**, **HAPLOID** cell _consisting of a:_ head (cell **body**) tail (**flagellum**) They contain lots of **mitochondria!**

Answer 78

**THICK** Filaments * ****Are made from **MYOSIN** fibers * Recall that myosin is a motor protein **THIN** Filaments * **** consist of mostly **ACTIN** fibers * also known as **microfilaments** * thin filaments also contain * **troponin** and **tropomyosin** **Actin** * **** is a protein * ...of which **microfilaments** are polymers **Myosin** * protein has both a **head** moiety and a **tail** moiety * A **dimer** is formed between **TWO** myosin proteins with their **tails intertwined*** * Large numbers of these dimers **combine** to create the long **myosin filaments** seen in the sarcomere. The globular **heads**, also called “**crossbridges**,” stick out from the myosin filament **at an angle**—which is the **RELAXED** conformation referred to as “**BENT**” in the sliding filament mechanism * Myosin heads have a high affinity for actin and will bind to it **unless** tropomyosin blocks the binding site

Answer 79

* The respiratory and gastrointestinal tracks would both be “front line” locations—if you will—in the battle against foreign invaders. * ***Both locations are interfaces between the internal and external environments.*** * For this reason, it would be an advantage for any organism to have lymph tissue, and therefore a concentration of immune cells, at these locations.

Answer 80

* Begins with FSH, which stimulates the maturation of ovum and the follicle in the ovary * FSH also stimulates **maturation of sperm** in males * LH then stimulates cells in the ovaries to secrete estrogen (estradiol), which signals the uterine wall to proliferate and prepare for a potential pregnancy. * Just before ovulation, a surge in the level of estrogen released causes a subsequent surge in levels of LH (luteal surge), which signals ovulation and the development of the corpus luteum. * The corpus lutem will begin secreting estrogen and high levels of progesterone to signal the uterine lining to prepare for implantation. * If **no** fertilization occurs the **corpus luteum degrades** and the menstrual lining sloughs off. * If implantation **does** occur, the corpus luteum **continues to secrete** estrogen and progesterone, **maintaining pregnancy**.

Answer 81

* is a semifluid mass of partly digested * expelled by the **stomach** * ....into the **duodenum** * moves through the intestines during digestion * ***IN THE STOMACH:*** * Partially digested * carbo's & proteins * UNdigested: * fats * Enzymes: * pepsin * amylase

Answer 82

* Are found **within Villi** * which are the finger-like projections that line the Small Intestine * is a **lymphatic capillary** that absorbs: * Fats * Carbohydrates * ...into the Lymph System

Answer 83

* At about week 3, the **notochord** forms from the mesoderm * Induces the overlying ectoderm to form the **neural plate** * which becomes the **neural tube** * and eventually the **spinal cord**

Answer 84

_In order to travel in blood or lymph, all lipids must either:_ 1. Bind to a protein carrier * such as **ALBUMIN** 2. Be formed into a **CHYLOMICRON** or **MICELLE**

Answer 85

* If an antigen binds to a B-cell’s antibody, the B-cell will undergo **differentiation** into:* * a **PLASMA** cell and a **MEMORY** B-cell* _The **plasma** cells:_ * manufacture **free** antibodies * and release them into the **blood** _The **memory** B-cells_ * **multiply** and **REMAIN IN THE BLOOD** * preparing the body for a **secondary** response

Answer 86

**HAPLOID, *"n"*** *"Ha"+"_ploid_"; "one _set_"* * Cells with only **ONE SET** of chromosomes * **ONE** gene for each trait * All **GAMETES** (like sperm & ovum) are haploid * Haploid cells are the result of **MEIOSIS** **DIPLOID, *"2n"*** *"di"+"_ploid_"; "two _sets_"* * Cells having **HOMOLOGOUS** chromosomes * **TWO** genes for each trait * All **SOMATIC CELLS** (aka "body cells"--basically any cell of the body **EXCEPT** for sperm & ovum) are diploid * Diploid cells are the result of **MITOSIS**

Answer 87

**Myosin** * protein has both a **head** moiety and a **tail** moiety * A **dimer** is formed between **TWO** myosin proteins with their **tails intertwined*** * Large numbers of these dimers **combine** to create the long **myosin filaments** seen in the sarcomere. The globular **heads**, also called “**crossbridges**,” stick out from the myosin filament **at an angle**— * which is the "**RELAXED** conformation" * referred to as “**BENT**” in the sliding filament mechanism * Myosin heads have a high affinity for actin* * and will bind to it **unless:*** ***tropomyosin** BLOCKS the **binding site***

Answer 88

The **VAGUS** nerve (**PARA**sympathetic) **SLOWS** the heart rate **SYMPATHETIC** nerves **INCREASE** heart rate

Answer 89

*DIGESTION:* **DUODENUM** ## Footnote *ABSORPTION: **JEJUNUM & ILEUM***

Answer 90

**A** ## Footnote The **RELAXED** state of the myosin head is **BENT** The **HIGH-ENERGY** state is the **STRAIGHT** position **ATP** is used to make this transition-- **priming** the pump (or **cocking** the hammer) * This makes A true * B states the same thing, but mixes up the high and low states * The power stroke, Answer C, does NOT use the splitting of ATP; this utilizes the potential energy stored in the myosin head from the hydrolysis of ATP to “pull the trigger.” * Answer D is also false because the myosin head spontaneously attaches to the actin filament for which it has very high affinity

Answer 91

The **RELAXED** state of the myosin head is in the **BENT** position The **HIGH-ENERGY** state is the **STRAIGHT** position

Answer 92

**C** ## Footnote **Cocked** and **dissociated** from the actin filament Prior to calcium entering the cell to **displace tropomyosin:** * the myosin head is **NOT** attached to the actin It is also **COCKED** * ****so that **after** attaching to the actin head, it **can** relax to its **BENT** position * and **DRAG** **the actin with it**

Answer 93

**Totipotent cells** * can form all the cell types in a body-- **PLUS (!)** the **EXTRAembryonic**, or **PLACENTAL**, **cells** * Embryonic cells within the first couple of cell divisions after fertilization are the only cells that are totipotent **Pluripotent cells** * can give rise to **ALL** of the cell types that make up the body * Embryonic stem cells are considered pluripotent **Multipotent cells** * can develop into **more than one** cell type * but are more **limited** than pluripotent cells * Adult stem cells and cord blood stem cells are considered multipotent

Answer 94

***Cartilage is found in:*** 1. _Appendages such as:_ * the **NOSE** and **EARS** 2. _At the ends of:_ * **LONG** bones (e.g., femur) 3. **_BETWEEN:_** * vertebrae 4. _At almost any:_ * **JOINT** or **ARTICULATION** * "Articulation"= the point of connection between* * two bones or elements of a skeleton* * (especially if the articulation allows motion)*

Answer 95

* To separate food molecules from each other (i.e., physical digestion) and break up those molecules into their monomers for absorption (i.e., chemical digestion). * These monomers are then used for both energy and as a source of carbon chains and amino acids.