MCAT: BIO 5

Created by jennifernewwin 

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What makes up the integumentary system?

All of your external features: hair, nails, skin as well as oil and sweat glands within skin.

Function of integumentary system?

thermoregulation, protection, environmental sensory input, excretion, innate immunity, blood reservoir, and Vitamin D synthesis.

Layers of the skin (top to bottom)

Epidermis and dermins

What is the epidermis made up of?

avascular, dead keratinized cells.

What is the dermis made up of?

vascular so it contains blood vessels, hair follicles, sebaceous glands (oil), sudeoriferous glands (sweat), and nerve endings. **Dermis is CT.

How does the skin play a role in thermoregulation?

When we are too hot, blood vessels migrate closer to the surface of the skin and DILATE to release heat. When we are cold and need to conserve heat, blood vessels will migrate down and CONSTRICT.

What is blushing a result of?

dilation of superficial blood vessels

Function of musculoskeletal system

body movement, support and stabilization, generation of heat, and maintenance of homeostasis.

Why do we shiver? What is a shiver physiologically?

Shivering is uncontrolled muscle contractions in order to produce heat.

Characteristics of skeletal muscle

striated, multinucleated, voluntary

tendons

connect bone to muscle

ligaments

connect bone to bone

agonist

aka prime mover. It is the muscle that produces most of the force during a particular joint action.

antagonist

muscle that opposes the prime mover. In some cases, it relaxes to give prime mover almost complete control over action or will maintain some tension on a joint and thus limit speen or range of prime mover. Helps prevent excessive movement, joint injury, or inappropriate actions.

synergist

a muscle/muscles that aid prime mover. Two or more synergists acting on a joint can produce more power than a single larger muscles. Actions of prime mover don't necessarily have to be identical to prime mover; synergist will also help stabilize joint or help modify direction of movement so action is more coordinated.

What is the quality of the hinges formed by most muscles and bones in the human body?

They make for a POOR LEVER SYSTEM; i.e. mechnical disadvantage. Muscles must create a force that is greater than the weight of the part of body we want to move.

What is the trade off between decreased force generated by lever system and speed/range of motion.

An decrease in force generates means an increased speed and range of motion.

Skeletal muscle anatomy (start from the muscle and go in)

muscle --> fasicles --> sarcolemma --> muscle fiber --> myofibrils

What are myofibrils made up of?

long bundles of actin and myosin fibers interconnected in repeating units called sarcomeres.

Where do you find the sarcoplasmic reticulum? What does the sarcoplasmic reticulum do?

Find it interwoven around the myofibrils. Responsible for sequestering Ca2+ away from the sarcomere prior to contraction.

thick filament

myosin filaments; during contraction, overlaps more with thin filament.

thin filament

actin filaments; during contraction, overlaps more with thick filament.

actin

two intertwined strads of g-actin (looks like pearl necklage) that form a helix. On each one of G-actin, there is an active site. Normally, troponin is set so it holds tropomyosin over active site so myosin can't bind. However, when calcium is bound to troponin, it lifts tropomyosin off which leaves active site exposed; myosin heads will bind. During contraction, more of its active sites will be bound to myosin heads.

myosin

like two golf clubs with their handles intertwined. Set up opposing each other/handles attached to each other via M-line. Have myosin heads.

myosin heads

Myosin heads have ATPase. Breaking ATP releases energy. Energy is used to change the shape of the myosin head.

A band

total width of myosin. Dark band. Doesn't change length during contraction. Myosin length is a constant.

I Band

Actin only with no myosin. End of one A band to the beginning of the next A band in the next sarcomere. As mucle contracts, it gets more narrow.

H zone

myosin only with no actin overlap. When muscle contracts, it'll get smaller.

M line

Chain in the middle. Used to bind myosin together. Holds myosin stable and centered.

Z line/disc

located at end of sarcomere. Where actin attaches. Also is connected to titan which helps centers myosin. They get closer together during contraction.

What is a sarcomere

functional unit of the muscle. Extends from Z-line to Z-line.

What is the neuromuscular junction? What occur there?

NMJ is the junction between a skeletal muscle and a motor/somative nerve. This is where Acetylcholine is released. Ach is the ONLY neurotransmitter released at the NMJ.

What is the default position of the myosin heads? High or low energy?

Low-energy position of myosin is BENT.

What is the high-energy position of myosin heads?

ATP is hydrolyzed to ADP and Pi which "cocks" myosin heads into a high energy, STRAIGHT position.

How do muscles contracT?

1.) AP spreads along sarcolemma of muscle fiber and down T-tubules. 2.) AP causes release of Ca2+ from sarcoplasmic reticulum. 3.) Ca2+ binds to troponin which causes tropomyosin to be lifted off of active site, exposing active site. 4.) Myosin's ATPase hydrolyzes ATP to ADP and Pi which cocks myosin head into high energy, straight position. 5.) Myosin heads bind to active sites forming myosin-actin cross bridges. 6.) Power stroke: myosin heads release ADP and Pi which allows myosin heads to flex into bent, low energy state, pulling actin along with it. 7.) Myosin head binds to ATP causing release from active site. 8.) If Ca 2+ still around, ATP will be hydrolyzed to ADP and Pi which will cock myosin head into high energy, straight position and allow it to attach to next active site.

What happens if no ATP is present in a muscle fiber?

Myosin heads cannot detach from actin and thus muscle cannot relax. Muscle will be stuck in a contracted position called "rigor." This is what happens when you die: "rigor mortis."

What happens if there is no Ca2+ present in the muscle fiber?

Since no Ca2+, active sites will remain covered by tropomyosin. Thus, no contraction can occur. Get flaccid paralysis.

What is a motor unit?

a motor neuron and the muscle fibers it innervates.

T or F: Do all cells/fibers in a skeletal muscle fire simultaneously during a contraction?

No. they do not. They fire according to what motor unit they are apart of.

For delicate movements/fine control, what would the motor unit be like?

very small motor units; i.e. motor neuron that only innervates 1 or 2 muscle fibers.

For gross movements, what would the motor unit be like?

large small motor units; i.e. motor neurons that innvervate lots of muscle fibers.

What determines the strength of a given contraction?

1.) the number of motor units being used. 2.) size of motor units being used. 3.) frequency of action potentials being sent (i.e. stimulation).

In which of the following would you find small motor units? A.) gastrocnemius B.) abdominals C.) Trapezieus D.) lateral rectus of the eye

D.

What is myoglobin? Where do you find it?

myoglobin is basically one subunit of hemoglobin and thus is only able to hold one molecule of O2. Skeletal muscle contain myoglobin because skeletal muscle require a lot of oxygen.

What would you most likely find in skeletal muscle? a.) actin, myosin, calcium, glycogen, proteins, hemoglobin b.) thick filaments, thin filaments, potassium, glycogen, myoglobin c.) proteins, actin, thick filaments, calcium, glycogen, myoglobin d.) intermediate filaments, calcium, glycogen, myoglobin

C

Where would you most likely find a differentiated skeletal muscle cell? A.) G1 B.) S phase C.) G2 D.) GO

D. Mature/differentiated skeletal muscle cells are frozen in Go and do not divide. They are like neurons in that way.

Characteristics of cardiac muscle

involuntary, striated, uninucleate

Contraction of cardiac muscles

cardiac muscle does contain sarcomeres and uses the same sliding filmanet mechanism as skeletal muscle.

Important features of cardiac muscle

contain myoglobin, a lot of mitochondria (prevents fatigue), intercalated discs containing gap junctions, and continues to divide after differentiation/maturation and thus ARE NOT STUCK in GO.

What is the function of gap junctions in cardiac muscle?

action potentials are passed through the gap junctions after reachign end of the purkinje fibers.

What is cardiac muscle considered "autorhythmic"?

Because it contracts at a set rate.

Do heart muscle cells contract in response to innervation by a nerve?

No. cardiac muscle is automatic. Even if you cut the heart out of the body, it would continue to contract. Innervation by a nerve only helps modify contraction of heart. But, innervations by a nerve is NOT necessary to make the heart contract.

Smooth muscle characteristics

involuntary, non-striated, uninucleate.

What things do the smooth muscle control?

gut, viscera, blood vessels, things you are not in voluntary control of besides heart.

In what types of muscle tissue would you find sarcomeres?

Cardiac and skeletal, NOT Smooth.

special characterisitcs of smooth muscle

Lack sarcomeres and troponin, does NOT contract via sliding filament mechanisms but uses a calcium-calmodulin cascade.

Multi-unit smooth muscle

Acts like skeletal muscle where one motor neuron can interact with multiple electrically isolated smooth muscle cells. Good for fine control.

Single-unit smoth muscle

Acts like cardiac muscle where all cells are joined together by gap junctions and is stimulated when NT flood the muscle causing contraction of ALL cells.

Dense body

attach to actin and intermediate fibers; serve to as anchors from which actin can exert force, may help coordinate tensions from both contractile machinery and cytoskeleton.

Intermediate filaments

tie dense bodies to each other and wrap around the whole cell in all places to form a net like structure.

Function of bone

support, protection, movement, mineral storage of Ca and phosphate, energy storage (fat as marrow), and blood cell formation

Bone cell types?

osteoclasts, osteocytes, osteoblasts

Osteocytes

mature bone cells surrounded by a mineral matrix

osteoclasts

bone cells that break downa nd resorb bone matrix, releasing the component minerals "Ca2+ and pH" back into blood.

Osteoblasts

Immature bone cells that secrete collagen, organic compounds, and minerals forming a bone matrix around themselves. Once they are completely enclosed by a matrix, they differentiate into osteocytes.

Hematopoesis

the making of blood cells

Red bone marrow

where you make blood cells

Yellow bone marrow

adipose in the long bonds of adults. Used for shock absorption. Is yellow b/c its adipose and only fat solution stuff can enter.

spongy bone

consists of trabeculae with very few osteons. Spaces between trabeculae are filled with bone marrow. It has a higher SA but is less dense, softer, weaker, and less stiff than compact bone. Highly vascularized.

compact bone

factiliates bone's main functions: to support whole body, protect organs, provide levers for movement, store and release calcium. Much more dense, stronger, harder, and stiff than sponger bone.

What is hydroxy appetite?

compound of Ca, Phosphate, and hydroxide. It is the mineral matrix responsible for a bone's strength and is the form in which most all of the body's calcium is stored.

What is cartilage? Is it vascularized or innervated?

A connective tissue made of collagen. Is not vascularized or innervated.

Where would you find cartilage?

nose, ear, ends of long bones, between vertebrae, at rib-sternum (sternocostal) joints. Anywhere you would want to reduce friction or have it be bendy.

Types of joints

fibrous (skull bones), cartilagenous (ribs to sternum), synovial (knee, elbow)

Penis

deposits sperm into the vagina.

Testicles

combined endocrine and exocrine glands that produce sex hormones and sperm. Contains the seminiferous tubules and leydig/interstitial cells.

scrotum

pendulous pouch of skin, muscles, and CT containing testes.

seminiferous tubules

where sperm are produced.

epididymis

site of sperm maturation and storage.

vas deferens

transport sperm from epididymis in anticipation of ejaculation.

seminal vesicles

contributes a viscous yellowish fluid containing fructose and other carbs.

prostate gland

secretes a thin, milky, alkaline substance into the semen to help neutralize acidic environment of vagina and help prolong life of sperm.

bulbourethral gland/cowper's gland

produces clear, salty, viscous secretion known as pre-ejaculate. This helps lubricate urerthra for spermatozoa to pass thru, neutralizing acids, any residiual urine or foreign matter.

urethra

tube that carries semen and urine to the end of the penis to be dispelled.

sperm

male gametes. Produced in testicles by seminiferous tubules and stored/nurtured in epididymis. SINGLE, HAPLOID cell consititng of head, tail, and lots of mitochondria.

Why do sperm have a lot of mitochondria?

Because they are motile and need lots of ATP

What is the technical plural and singular form of the word sperm?

singular = spermatozoon. Plural = spermatozoa.

Ejaculation pathway

sperm leaves epididymis via vas deferens. Vas deferens arches back up into the pelvis and then back down toward the penis. Along the way, seminal vesicles, prostate gland, and bulbuorethral/Cower's gland all secrete various lubricants and nutrients into the ejaculate. Near the base of the penis, the vas deferens empties into the urethra coming from the urinary bladder. The urethra then travels down the penis.

pathway of sperm creation to ejaculation.

SEVEN UP: seminiferuos tubules --> epdidymis --> vas deferens --> ejaculatory duct --> (nothing) --> urthera --> penis.

What is the acrosome?

a lysosome in the form of a thin cap; contains enzymes that are later used to penetrate the egg if the sperm is successful.

What is the difference between a spermatozoon and a speormatogonium?

Spermatogonium is diploid/2n while spermatozoa/spermatozoon is haploid/n.

Substance added to ejaculate by prostate gland

thin, milky white fluid containing calcium, citrate, and phosphate ions, clotting enzyme, and protein-hydrolysing enzyme (PSA). PSA is prostate specific antigen which helps keep semin in liquid form.

Substance added to ejaculate by seminal vesicles

viscous, yellowish fluid. Contains fructose, other carbs, citrate, prostaglandins, and protein. Fructos gives sperm a way to make ATP to power movements.

Substance added to ejaculate by bulbourethral/Cowper gland

during sexual arousal, produce clear slippery fluid that lubricates the head of the penis in preparation for intercourse. Also protects sperm by neutralizing acidity of residual urine in urethra.

What is cleavage in terms of embryology?

mitosis without change in size

morula?

8-cell zygote

What is gastrulation?

at about week 2, cells migrate for form the three germ layers.

What is neurulation?

at about week 3, the notochord forms from mesoderm and induces the overlying ectoderm to form the neural plate, which becomes the neural tube, and eventually the spinal cord.

Ectoderm

epidermis, nails, tooth enamel, lens of the eye, pituitary gland, CNS, PNS, and autonomic NS.

Mesoderm

Dermis, muscle, bone, CT, kidneys, genitalia, and most interal organs EXCEPT liver and pancrease.

Endoderm

entire digestive tract, thyroid, parathyroid, urinary bladder, the lining ONLY of the lungs, liver and pancreas.

Vagina

tube used for discharge of menstrual fluid, receipt of penis and semin, birthcanal.

Cervix

the lower, narrow part of the uterus where it joins with the top end of the vagina. Has an opening to allow sperm and menstrual fluid to move through; during menstruation, cervix stretches open slightly to allow the endometrium to be shed. Also dilates for chilbirth.

Uterus

thick muscular chamber used to harbor fetus, provide a source of nutrition, and expel fetus at end of development.

Fallopian tubes

canals leading from ovary to the uterus. Contain cilia which help convey the egg down the tube.

Ovaries

female gonads. Where egg cells (ova) and sex hormones are produced. Where you would find follicles.

describe the journey eggs take while being produced

eggs are female gametes. Egg begins meiosis as a germ line cell in the ovary of a female fetus and is arrested at Prophaes I of Meiosis at birth. Not until puberty and menstruation is Meiosis I completed. Meiosis II is not completed until after sperm arrives.

From birth to fertilization, egg is called ______.

oocyte

After fertilization, egg is called an _______.

ovum

What is the technical plural and singular form of the word egg?

singular = ovum. Plural = ova.

What's the difference between an oocyte and oogonium.

Oogonium is 2N while oocyte is N.

Menstrual Cycle

Begins with FHS, which stimulates the maturation of 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 prepares the uterine wall for pregnancy. Just before ovulation, a surge in estrogen causes a surge in LH (luteal surge), which causes ovulation. If no fertilization occurs, the corpus luteum degrades and the menstrual lining sloughs off. If implantation does occur, the corpus luteum secretes estrogen and progesterone, maintaining pregnancy.

Identify and describe the portion of the menstrual cycle that illustrates a positive feedback mechanism.

release of estradiol/estrogen by the ovary feeds back on the anterior pituitary which causes more LH to be released. More LH released makes ovary produce more estadiol and more LH and so on.

Fertilization

usually occurs in fallopian tubes. Sperm and egg, traveling towards each other, generally meet there. Implantation normally occurs in the uterus, but can occur in the fallopian tubes leading to a "tubal" or "ectopic" pregnancy.

symptoms of menopause

hot flashes, vaginal dryness, and atrophy of breast tissue. ***menopause a result of decreased estrogen and progesterone levels.

If hormone levels go up unexpectedly (estrogen and progesterone levels), what could that mean?

High levels COULD cause unexpected menstruation ONLY IF that increase was followed by a sudden decrease. It is the drop in hormone levels that causes menstruation, not the increase.

What is often a side effect of giving elderly women estrogen/progesterone therapy for treatment of osteoporosis?

unexpected menstruation due to the erratic increase and decrease of hormone levels.

What accounts for the build up and maintenance of the uterine lining?

estrogen and progesterone. The build-up and maintenance of the unterine lining is necessary to have menstuastion or the sloughing off of the uterine lining.

Menstruation vs. Ovulation

Ovulation requires a surge in hormone levels. Menstruation requires a sharp decline.

Persistant low levels of estrogen/progesterone can lead to what?

menopause

What would you expect to find in abundance at the axon/axon hillock and the NMJ, respectively?

axon/axon hillock = lots of Na/K pumps
NMJ = neurotransmitter and calcium channels

what types of glands does the skin contain?

exocrine, not endocrine glands.

Before calcium comes, what is the relative state of the myosin head?

Cocked and dissociated from the actin. **cocked and not bent becuase it is anticipating a contraction.

totipotent vs. pleuripotent

all embryonic cells are totipotent meaning they can differentiate into any cell. Pleuripotent cells were once totipotent but aren't any longer meaning they are partially differentiated and don't have as much opportunity to become anything they want like totipotent.

What is RBC count used for?

indicator of health and function of bone marrow.

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