Class 10: Muscular, Skeletal, and Respiratory Systems

To increase power

- more motor units are activated - using all the neurons = motor unit recruitment

Rigor Mortis

No ATP, dead - Ca2+ in SR leaks out and naturally being pulled to troponin, moving tropomyosin (no ATP present to be able to pump Ca2+ back into SR) AT REST, myosin is in HIGH energy state - myosin will bind actin and pull but not release because there is not ATP (tells you how long a person has been dead)

Vitamin D (calcitrol)

"helps you withdrawl Ca2+ from food" - comes from sun - vitamin D is activated by PTH - similar actions as PTH - allows you to get Ca2+ out of bones for your body to absorb - allows the small intestine to take up Ca2+ (absorb it) - increases reabsorption of phosphate in kidneys

Oxygen Debt

(back in the day: body wanted to conserve glucose) Oxygen Debt - extra oxygen needed after exercise to: 1. replenish O2 stored on myoglobin (that you used) 2. convert lactic acid (in bloodstream) back into pyruvate (oxidation reaction) - remember lactic acid is NEEDED to replenish NAD+ via pyruvate (reduction reaction) *this extra oxygen used to repay the oxygen debt comes from hemoglobin*; see next slide - want to move lactic acid out of muscle - liver turns it back to pyruvate - if you keep lactic acid and pyruvate you can rebuild glucose via gluconeogenesis - if you lose CO2, don't lose lactate and can make glucose

What is a motor unit?

*remember a neuron is required to stimulate a muscle cell to contract* = a motor neuron plus all of the muscle cells it controls - motor units contract in an all or none fashion

Intro to connective tissue

- "loose" or "dense" based on the amount of collagen they contain; those with a lot of collagen are dense tissues, and tend to play more supportive roles. - Ligaments connect bones to bones and are made primarily of collagen, thus they are a type of dense connective tissue - tendons connect bones to muscle (dense CT) - Adipose tissue, or fat, contains virtually no collagen and is a type of loose connective tissue - Collagen is found in both loose and dense connective tissue; the difference between the two is the amount of collagen - The extracellular matrix is the mix of proteoglycans and glycosaminoglycans that exists as the tissue between cells, It is responsible for holding on to water (among other functions); it is a component of loose connective tissue and many other tissues

Energy Storage in Myofiber (=muscle fiber, made of myofibrils)

- ATP provides the energy for contraction, and supplies must be regenerated by glucose catabolism - however glycolysis and the TCA cycle are not fast enough to keep pace with the rapid ATP utilization during extended contraction - there is a need for an intermediate-term energy storage molecule = creatine-phosphate - during contraction, hydrolysis of creatine-phosphate drives the regeneration of ATP from ADP + Pi

Which of the following would most likely become a major concern of mortality in MG patients? (MG = Myasthenia gravis = a major presenting symptom is fluctuating skeletal muscle weakness.) A. Cardiac failure B. Muscle weakness in the upper limbs C. Paralysis of the facial muscles D. Respiratory distress

- MG is a disease affecting skeletal muscle; therefore, all skeletal muscles in the body are susceptible (eliminate choice A). - A very important skeletal muscle in humans is the diaphragm; in severe MG patients, death can occur due to respiratory distress or arrest. Paralysis of facial muscles and weakness of upper limbs can occur; however, they are generally not the primary cause of mortality (eliminate choices B and C; choice D is correct).

Thermoregulation is primarily a function of the

- dermis - when temperature rises, blood vessels in the dermis dilate to release heat and sweat glands are activated - when temperature falls, blood vessels constrict to retain heat. Also involuntary muscle contractions occur (shivering) to produce heat

During puberty and sexual maturation, what impact do androgens and estrogens have on the epiphyseal plate?

- The hormones ossify the epiphyseal plate, thus stopping growth - Androgens and estrogens aid in the eventual ossification of the epiphyseal plate, which stops further growth and results in a person reaching his/her final height - This ossification does not result in a layer of cartilage being formed as mature bones are composed of collagen and hydroxyapatite, a calcium-phosphate crystalline solid

(smallest) tidal volume, inspiratory capacity, vital capacity, total lung volume (largest)

- The tidal volume (TV) is the amount of air that moves in and out of the lungs with normal breathing. - The inspiratory capacity (IC) is the maximum amount of air that can be inspired after a relaxed expiration. It is equal to the tidal volume plus the inspiratory reserve volume (IRV). Thus, IC = TV + IRV. - The vital capacity (VC) is the maximum amount of air that can be forced out of the lungs after taking the deepest breath possible. It is equal to the inspiratory capacity plus the expiratory reserve volume (ERV). Thus, VC = IC + ERV. - Finally, the total lung capacity is the total volume of the lungs. It is equal to the vital capacity plus the residual volume. Thus, TLC = VC + RV, and TV < IC < VC < TLC.

Excitation-Contraction Coupling

- Tropomyosin blocks myosin active sites on actin - Troponin = a Ca2+ binding protein and is attached to tropomyosin - when Ca2+ binds to troponin, it shifts tropomysoin off of the myosin binding sites - depolarization triggers release of Ca2+ - ACh triggers depolarization - motor neuron triggers release of ACh EXCITATION = depolarize muscle cell - open Ca2+ channels in SR - Ca2+ enters cytosol CONTRACTION = troponin binds Ca2+ - troponin changes shape - pulls tropomyosin off the myosin binding sites - myosin binds to actin *all muscle cells must be stimulated by a neuron - or else they won't contract. Contraction also requires ATP (to reset myosin and pump Ca2+ back into SR or else rigor mortis occurs)*

Sarcomere structure

- Z-lines: define the boundaries of each sarcomere (shared by neighboring sarcomeres) - come closer together at contraction - 3 Z lines = 2 sarcomeres - Actin: thin filaments attached to Z lines - Myosin: arms in between actin filaments, will hook onto actin - M-line: located in the middle of the sarcomere - I-band: contains only thin filaments - located on either side of the Z lines - located where there is no myosin - becomes more narrow at contraction - A-band: length of a thick filament - located where myosin and actin - H-zone: consists of only thick myosin - disappears at contraction when thin filaments overlap **size of thick and thin filaments doesn't change during contraction What 2 areas disappear during contraction? - H zone and I band (A band is unaffected during contraction)

reabsorption

- a the process of absorbing again - process whereby renal tubules return materials necessary to the body back into the bloodstream

Force Expiration - ACTIVE contract

- accessory muscles (abdominal muscles; skeletal muscles) - force a decrease in lung volume and increases pressure

desmosomes

- also known as adhering junctions, hold cells together, but do not form a seal. - they are found in skin cells, as well as in other organ tissues that are subject to stretching.

A motor unit is the group of skeletal muscle cells innervated by a single motor neuron. The muscle cells of a motor unit:

- are multinucleate and do not share cytoplasmic contents with each other. - Skeletal muscle cells are long cells formed by the fusion of many smaller cells with one another, thus they are multinucleate. They lack cell walls (as do all animal cells), but do have a plasma membrane. - The plasma membranes of skeletal muscle cells, however, does not contain gap junctions (as do the plasma membranes of cardiac and smooth muscle cells) so they do not share cytoplasmic contents.

Calcitrol and PTH

- both increase serum [Ca2+] - increase bone resorption, which helps to increase serum calcium - PTH by increases calcium reabsorption at the kidney - calcitriol by increases calcium absorption by the intestines **PTH has an indirect role in increasing intestinal absorption of Ca2+ by increasing the conversion of calcidiol to calcitriol ***In the absence of vitamin D, intestinal absorption of calcium will be reduced, so plasma calcium levels will be lower than normal. This would trigger the release of PTH to increase plasma calcium through other means, primarily via bone resorption liver and kidney make calcidiol form

Liver, parathyroid, thyroid

- directly involved in the synthesis of substances important in bone remodeling. - Calcitonin (made in the thyroid) - parathyroid hormone (made in the four parathyroid glands), - the biologically active form of Vitamin D (which requires hydroxylation reactions in both the liver and kidneys) coordinate bone remodeling by acting on osteoblasts and osteoclasts in the bone. - The liver converts cholecalciferol to calcidiol, which is then converted to calcitriol (the active chemical form of the vitamin) in the kidneys. - These hormones also act on the intestines and kidneys to regulate levels of calcium and phosphate, the constituents of the inorganic component of bone (hydroxyapatite).

Myoglobin

- found in muscle cells - muscle is highly aerobic tissue, with abundant mitochondria - myoglobin is a globular protein and is similar to one of the 4 subunits of Hb - Each myoglobin molecule is capable of binding one oxygen, because myoglobin contains one heme per molecule. - made of only a single protein subunit - the role of myoglobin is to provide an oxygen reserve by taking O2 from Hb and then releasing it as needed During prolonged contraction, the supply of O2 runs low, and metabolism becomes anaerobic - lactic acid is produced and moves into the bloodstream causing a drop in pH - the liver picks up this lactate and converts it into pyruvate, which can then be used in various pathways (gluconeo, glycolysis, fatty acid metabolism)

Hemoglobin

- is an oxygen-carrying protein found in red blood cells. - It is made up of four protein subunits that display cooperative binding. - Enzymes (or in this case, transport proteins) that display cooperative binding have sigmoidal curves - In order to display cooperative binding, a protein must be made up of more than one subunit. - Since myoglobin is made of only a single subunit, it cannot display cooperative binding and would have a simple saturation curve - cooperative binding of Hb = binding of O2 increases binding of other O2, dissociation of O2 increases dissociation of other bound O2) - Hemoglobin would have a sigmoidal curve while myoglobin would have a simple curve

Don't Forget (muscle contraction is determined by what branch of the NS?)

- muscle contraction is controlled by somatic nervous system, which controls voluntary movement and releases ACh 1. There is no ATP used in the power stroke 2. When you run out of ATP, you can't release the actin from myosin (cannot fully relax) 3. Myosin head groups operate asynchronously (think like tug of war) (a force is generated constantly with time)

Fine motor control

- precise movement - will have more motor units, less cells, more neurons - will have smaller motor units but more ex: face, eyes, and hands *many small motor units*

Relaxed Expiration - PASSIVE

- relaxing diaphragm lungs: due to elastic tissue the lung snaps back, DECREASE VOLUME, INCREASE PRESSURE

Skeletal Muscle Fiber Types

- slow twitch (red oxidative)l Type I - fast twitch (type IIA) (white oxidative) - fast twitch (type IIB) (white fast twitch)

sarcoplasmic reticulum (SR)

- stores Ca2+ within the cell and releases it when the T-tubule is depolarized (via ACh)

Surfactant

- type II alveolar cells produce surfactant helps reduce water's surface tension - an H2O drop in alveoli walls will make them collapse, pull walls toward itself & cause closing of alveoli and loss of surface tension - would have to breathe harder and faster

tight junctions

- which are also known as occluding junctions - form a seal between the membranes of adjacent cells. - they are found in structures such as the intestines as well as the entire nephron tubule - tight junctions keep water-soluble substances from "leaking" between the cells.

Bohr Shift

-Increased CO2 in blood increases H+ -Lower pH reduces hemoglobin's affinity for O2 -Results in a shift of oxyhemoglobin dissociation curve to the right -Facilitates oxygen unloading 70% - 98% - oxygen to tissue under normal conditions 70% - 60% - extra O2 (released from hemoglobin due to lowered pH) to tissue under Bohr conditions *any rightward shift of a Hb saturation curve will represent a decrease in affinity for O2-Hb, which results in the Hb giving more O2 to the tissues (good thing) - lungs stay saturated with Hb-O2 because these are different conditions than the tissues

Canaliculi of osteon

-Tiny, interconnecting channels within bone connective tissue -Extend from each lacunae, travel through lamellae, and connect to other lacunae and the central canal -House osteocyte cytoplasmic projections permitting intercellular contact and communication -Allow travel of nutrients, minerals, gases, and wastes between blood vessels and osteocytes *canaliculi get their nutrients from the central canal blood vessel (VAN)

Sliding Filament Theory

1. Myosin binds to actin - also called "cross-bridge formation" - requires the presence of Ca2+ - myosin arm must also already be in high energy conformation/state 2. Myosin pulls actin toward the center of the sarcomere - also called the "power stroke" (even though ATP is not used here) (using previously stored energy) 3. Myosin releases actin - requires the presence of ATP (no ATP hydrolysis in this step, but ATP is attached to myosin, allosterically) 4. Myosin resets to high energy conformation - requires ATP hydrolysis (ATP -> ADP) - myosin arm returned to high energy conformation (back to step 1)

Conduction Zone pt.2

1. Nose/Nasal Cavity Mucocilliary escalator: sweeps mucous produced by goblet cells to catch pathogens/particles - escalates, sweeps infected mucous up 2. Goblet Cells - produce mucous

Bone Cells

1. osteoblasts = builders of bone - build most of thee extracellular matrix - can still divide 2. osteocytes = mature cell types (mature osteoblast cells) - maintain bone - maintain the extracellular matrix - can't divide (except for lymphocytes and hepatocytes) (osteoclasts = carry Ca2+, break down bone and activated by PTH)

Bone (Skeletal System) Functions

1. structure, support and movement 2. protection - skull, spine, ribcage, pelvis 3. red marrow storage - blood cell production - hematopoiesis makes RBCs, RBC synthesis via EPO hormone, B cells mature here 4. mineral storage - specifically, calcium storage for the rest of body - phosphate storage - hydroxyapatite

Small motor units

10 - 20s muscle cells controlled by a single motor neuron *contraction produced is not as strong ex: fingers, eyes (dilation and contriction of pupil/lens = autonomic movement of eye but somatic has motor units), face, mouth

Large motor units

100s - 1000s of skeletal muscle cells controlled by a single motor unit *will produce stronger contraction ex: legs, glutes, back, arms (biceps)

Major player of bone turnover

= PTH; would replace synthetically if gland remove (would not replace calcitonin if thyroid gland was removed)

bone 'resorption'

= bone breakdown - losing substance

Resipiration

= exchange of gases between tissues a) external: gas exchange between lungs (air) and blood - happens in alveoli b) internal: gas exchange exchange between blood and tissue - happens in capillary beds that aren't in lungs *NOT always occurring together. Water in your lungs will not result in gas exchange - no respiration -

Motor Units

= group of skeletal muscle cells controlled by one somatic motor neuron range: 4 - 1000s controlled by 1 neuron

Skin 1. 3 layers and tissue types2 2. Thermoregulation

= provides a substantial barrier to water loss (also acts as innate immune defense; someone who suffered from severe burns would be more susceptible to skin infection and dehydration) 1. 3 Layers and their Tissue Types a) epidermis = epithelial tissue (ectoderm) b) dermis = CT (mesoderm) - nerve endings, hair follicles, blood vessels, glands c) hypodermis = fat (mesoderm) 2. Thermoregulation a) cold: no sweat, shivering, vasoconstriction b) hot: sweat, no shivering, vasodilation

Compact Bone

= still living tissue with living cells - but don't want capillary beds in it, would be weaker - osteon = unit of compact bone - blood vessels run (VAN) runs through central canal of osteon - lamellae = layers around osteon - lacunae = caves for a single osteocyte - canaliculi = cytoplasmic tubes that extend between lacunae and allow for cells to exchange nutrients and waste - canaliculi connect osteocytes and exchange with blood supply as well *Individual osteocytes communicate with one another via gap junctions

Ventilation

= the movement of air in and out of system ("conduction")

T-tubules

= transverse tubule = invaginations of the cell membrane allow an action potential to travel deep into the skeletal muscle cell - the interior of the T-tubule is the same as the outside environment (analogous to lumen being outside material in GI tract) - ensure depolarization from the neuromuscular junction reaches the SR

Pemphigus vulgaris results from autoantibodies directed against a protein found between keratinocytes (skin cells). Which skin layer would you expect to be involved in the blisters seen in these patients? A. Epidermis B.Dermis C.Hypodermis D.Subcutaneous tissue

A. Epidermis The outermost layer of the skin is the epidermis, made up primarily of cells called keratinocytes (choice A is correct). The dermis is beneath the epidermis and contains collagen and elastic fibers which help support the skin (choice B is wrong). The hypodermis, also known as the subcutaneous tissue, is primarily fat (choices C and D are wrong).

A mutation leading to a loss of function in which of the following hormones would have the greatest impact on enzyme activation in the stomach? A. Gastrin B. Cholecystokinin C. Erythropoeitin D. Secretin

A. Gastrin Gastrin is secreted from G cells in the stomach, and stimulates acid (activates parietal cells) and pepsinogen secretion (activates chief cells), as well as increases stomach motility. Hydrochloric acid (HCl) cleaves the zymogen pepsinogen to active pepsin; a mutation leading to loss of gastrin function would impair HCl secretion and thus pepsin activation (choice A is correct). CCK (cholecystokinin) triggers release of bile and also works to regulate the flow of chyme through the pyloric sphincter and into the small intestine, but does not impact gastric enzyme activation (choice B is wrong). Erythropoeitin stimulates red blood cell production in the bone marrow and is made by the kidneys, thus it is not relevant to this question (choice C is wrong). Secretin triggers the release of pancreatic exocrine secretions (including digestive enzymes and aqueous bicarbonate) into the small intestine, and is not involved in gastric enzyme activation (choice D is wrong).

As the pH of the body decreases, how is ventilation rate impacted? A. Increased to release CO2 B. Decreased to preserve CO2 C. Increased to move more O2 into the blood D. Decreased to limit the transfer of O2 into the blood

A. Increased to release CO2

Which of the following does NOT describe the esophagus? A.The opening of the esophagus is protected by the epiglottis. B.The upper esophagus is composed of skeletal muscle. C.Peristalsis begins in the esophagus. D.The esophagus is separated from the stomach by the cardiac sphincter.

A.The opening of the esophagus is protected by the epiglottis. The trachea (not the esophagus) is protected by the epiglottis, as it prevents food or liquids from entering the lungs when swallowing (choice A does not describe the esophagus and is the correct answer choice). The upper portion of the esophagus is made of skeletal muscle so that swallowing can be initiated voluntarily (choice B describes the esophagus and can be eliminated), but this merges quickly into smooth muscle, which provides the peristalsis to move the bolus down to the stomach (choice C describes the esophagus and can be eliminated). The cardiac sphincter separates the esophagus and the stomach (choice D describes the esophagus and can be eliminated).

Fast Twitch: IIA

AKA: oxidative fibers/white oxidative Myoglobin Content: medium Capillary Network: medium Speed of Contraction: medium Mitochondrial Numbers: medium, some oxidative metabolism Fatigue Resistance - medium (30 minutes to an hour) Force Generated: - medium Example: - legs of 5K runners (intermediate runners) - basketball (some running for slow twitch, but has explosive movements like dunking - type IIA) - soccer - tennis

Slow Twitch

AKA: red fibers (very high myoglobin content, aerobic) Myoglobin Content: very high Capillary Network: dense Speed of Contraction: slow Mitochondrial Numbers: high Fatigue Resistance: high (can work for hours, think marathon) Force Generated: low Example: - legs of marathoners - endurance - posture (back muscles)

Fast Twitch IIB

AKA: white fast twitch fibers Myoglobin Content: low Capillary Network: sparse-low Speed of Contraction: fast Mitochondrial Numbers: low, not oxidative rather glycolytic Fatigue Resistance: low (1 min) Force Generated: high Example: - legs of sprinters - weightlifters - football players

Intro to the Conduction Zone

Anatomical dead space is the portion of the respiratory tree where gas exchange does not take place, also known as the conduction zone. Inhaled air follows this pathway: nose (CZ) nasal cavity (CZ) pharynx (CZ) larynx (CZ) trachea (CZ) bronchi (CZ) terminal bronchioles (CZ) respiratory bronchioles (RZ) alveolar ducts (RZ) alveoli (RZ)

Conduction Zone and Nervous System

Asthma - parasympathetic system is overactive and bronchi are constricted sympathetic - causes dilation and opens airways

Sliding Filament pictures

Attach - cross bridge formation: myosin binds to actin due to presence of Ca2+ *requires the presence of Ca2+* Pull - power stroke in myosin pulls actin toward the center of the sarcomere releasing ADP + Pi - myosin returns to its low energy state (no ATP used here) Release - new ATP allows the release of myosin from actin (still in low energy state) - requires only presence of ATP (no hydrolysis here) Reload - ATP is cleaved (hydrolysis) & myosin is reset to high energy state

How do troponin and tropomyosin work to regulate skeletal muscle contraction? A. Globular troponin binds calcium, a conformational change in protein pulls filamentous tropomyosin, and actin binding sites on myosin are exposed. B. Globular troponin binds calcium, a conformational change in protein pulls filamentous tropomyosin, and myosin binding sites on actin are exposed.

B. Globular troponin binds calcium, a conformational change in protein pulls filamentous tropomyosin, and myosin binding sites on actin are exposed. B. Troponin is the regulatory protein that binds calcium This induces a conformational change in troponin that pulls on tropomyosin in order to expose the myosin binding sites on actin. This allows interaction of actin and myosin, and contraction, to occur

Connective Tissue and Bone Functions

Cells in a matrix Matrix (consists of 2 things) = glop and fibers glop (ground substance) - liquid (calcium phosphate in blood plasma) - solid (calcium phosphate in bone = hydroxyapetite) *liquid to solid glop exists on a continuum fibers 1. collagen (strength) 2. elastic (flexibility/recoil) *bone is a type of CT *muscle is NOT a type of CT

Long Bone Anatomy

Diaphysis (compact bone) = shaft of bone, hollow tube that contains medullary cavity - contains yellow marrow (fat) - deals with pressure in each epiphysis Epiphysis = upper and lower ends, interact with joints - contains spongy bone that has red marrow (hematopoiesis =RBC formation = RBCs, WBCs, and platelets made here), also B cells mature here - spongy bone provides structure (contains compact bone layer lining it) Epiphyseal plate = growth plate where lengthening occurs as you grow - epiphyseal line forms when you're older and no more growth occurs - break plate young = just becomes bone, no growth can occur here now - growth plate = hyaline cartridge that is actively produced by chondrocytes *compact bone is on outer layer of bone - contains osteocytes - contains osteons (spongy bone has osteocytes but no osteons)

Excitation-Contraction Coupling pt. 2

EXCITATION: - an AP of the skeletal muscles travels down at T-tubule (depolarization), triggereing the SR to flood the cytosol of the cell with Ca2+ (will quickly be reabsorbed back into SR) COUPLING: - Ca2+ binds to troponin causing it to change shape, this moves tropomyosin off the myosin binding sites. As soon as the myosin binding sites are exposed, myosin binds to actin STEPS: - move muscle - ACh released - T-tubules depolarized - SR released Ca2+ - Ca2+ binds to troponin, causing it to change shape - moves tropomyosin off of myosin binding sites - myosin pulls actin (in order for myosin to release actin- requires the presence of ATP no ATP hydrolysis in this step, but ATP is attached to myosin, allosterically. Then myosin resets to high energy conformation- requires ATP hydrolysis (ATP -> ADP)- myosin arm returned to high energy conformation; ATP is also required to pump Ca2+ back into the SR via Na+KATPase) *if you don't release max contraction, process repeats itself - all or none -

Muscle Energy Stores

FASTEST 1. creatine-P + ADP --> creatine + ATP (doesn't require O2, fast, doesn't last very long) = substrate level phosphorylation - use for short, explosive movements 2. glycolysis = 2 net ATP + 2 NADH + 2 pyruvate (anaerobic doesn't require O2, produce lactic acid) 3. aerobic respiration = make most E but delayed = 30 ATP + 6CO2s + 6H2Os - myoglobin = oxygen storage - myoglobin replenishes O2 (muscle cells are limited as to how much oxygen they have) (acts as an emergency store of oxygen inside the muscle cell) - myoglobin appears red because it is 1/4 Hb (less O2) ; white meat of chicken = breast tissue because they don't fly; dark meat would be where myoglobin is like in legs SLOWEST

Fibrous, Elastic, Hyaline Cartilage

Fibrous cartilage = - is the strongest and least flexible type of cartilage and it is found in places like the intervertebral disks as well as the pubic symphysis - it does not eventually ossify; this would create a completely rigid structure whereas the cartilage does provide a little bit of flexibility (imagine if your spine was complete bone) Elastic cartilage = - provides the most flexibility and is found in places like the outer ear and the epiglottis. Hyaline cartilage = - balances support with flexibility and is found on the ends of bones, at the joints. It is also known as articular cartilage. (makes up epiphyseal plate) - found in the ribs, nose, larynx, trachea

Smooth muscle

Function: involuntary with neural/hormonal/mechanical stimulation - autonomic and autorhythmic (stimulate themselves to beat) Location: - around hollow organs or vessels (blood vessels, bronchi of lungs, GI tract) - constrict or dilate hollow vessels or glands Nuclei: mononucleated/uninucleate Microscopic Appearance: non-striated (both cardiac muscle and skeletal muscle include Ca2+ binding to troponin; smooth muscle has Ca2+ calmodulin binding, MLCK activation) - the primary source of calcium ions in smooth muscle comes from the extracellular space, an AP opens Ca2+ channels in cell membrane *contains gap junctions like cardiac muscle

Skeletal Muscle

Function: movement and stability of body Location: attached to bones, directly or indirectly Nuclei: multinucleated Microscopic appearance: elongated and striated (presence of sarcomeres) Hierarchy (starting small): PROTEIN FILAMENTS - actin (thin 2 chains of actin) & - myosin (thick filament) SARCOMERE - smallest contracting unit, made of filaments MYOFIBRILS - string of sarcomeres MUSCLE CELL - bundle of myofibrils (organelle, larger than mito & nucleus) - muscle cell = a myofibers FASCICLES - bundle of muscle cells WHOLE MUSCLE - bundle of fascicles **contains no gap junctions or other cell-cell junctions **They lack cell walls (as do all animal cells), but do have a plasma membrane. The plasma membranes of skeletal muscle cells, however, does not contain gap junctions (as do the plasma membranes of cardiac and smooth muscle cells) so they do not share cytoplasmic contents.**

Cardiac Muscle

Function: pump blood, involuntary - autonomic and autorhythmic control (can generate its own contraction) Location: only in heart Nuclei: mononucleated/uninucleate Microscopic Appearance: striated (sarcomeres and contacts just like skeletal muscle) - Ca2+ found in cardiac muscle is found in the SR AND extracellular environment via VG-Ca2+ channels (has gap junctions)

Skeletal Muscle

Function: voluntary Location: attached to bones Nuclei: multinucleated Microscopic appearance = striated - Ca2+ found in skeletal muscle is found from SR (not extracellular environment)

Respiratory System Functions and Definitions

Functions: 1. Exchange of gases (CO2/O2) - getrid of CO2 - get O2 2. pH regulation (of blood) - short term/fast - major line of defense against major body pH changes (as opposed to kidney regulation) Definitions: 1. Ventilation 2. Respiration *ideally these occur together but can do them separately, they are independent of one another*

when contracting the diaphragm

Inspriation - ACTIVE contract: diaphragm contracts -> pulls the pleuras, opening/increasing the lung volume - lungs expand = alveoli expand, alveolar pressure decreaes - air will get sucked into the alveoli through the respiratory tract INCREASE VOL DECREASE PRESSURE

Which of the following do both skeletal and cardiac muscle cells undergo? I. Depolarization via fast voltage-gated sodium channels II. Depolarization plateau due to slow voltage-gated calcium channels III. Repolarization via voltage-gated potassium channels

Item I is true: fast voltage-gated sodium channels are responsible for depolarization in both skeletal muscle cells and cardiac muscle cells (III only can be eliminated). Item II is false: only cardiac muscle cells have a depolarization plateau (I, II, and III can be eliminated). Item III is true: voltage-gated potassium channels are responsible for repolarization in both cell types (I only can be eliminated).

Ventilation

Lung stuck to inside wall of chest cavity, to... 1. reduce surface tension 2. slight negative pressure (-4mmHg) 1. visceral pleural membrane is attached to the surface of the lungs 2. parietal pleural membrane attached to diaphragm, lines inner side of chest cavity Inspiration - ACTIVE CONTRACT - contracting diaphragm -> skeletal muscle - increases size/volume of chest cavity - pressure decreases, air rushes in Expiration - PASSIVE - diaphragm relaxes - lung elastic recoil - decrease size/volume of chest cavity - pressure increases, air pushed out Forced expiration - ACTIVE - contract abdominal muscles - increased pressure in abdominal cavity pushes diaphragm up past normal resting position - air pushed out forcefully *people who lose their lung elasticity will not be able to passive exhale - must do forced expiration instead*

Conduction Zone: Cartilage

R/L Primary Bronchi - largest rings of cartilage here Secondary (lobar) Bronchi - plates of cartilage Tertiary Bronchi - very little cartilage Terminal Bronchioles - no more cartilage after 7th branching (don't need cartilage to hold bronchi open)

Conduction Zone: Lining Cells

R/L Primary Bronchi - tall ciliated columnar epithelium cells with goblet cells Secondary (lobar) Bronchi - tall ciliated cells with goblet cells Tertiary Bronchi - tall ciliated cells with goblet cells Terminal Bronchioles - thin short cells (simple squamous epithelium), no cilia - now cannot sweep and remove dirt/dust out would only be able to consume via macrophage

Conduction Zone: Smooth Muscle

R/L Primary Bronchi - very little at top Secondary (lobar) Bronchi - very little Tertiary Bronchi - mostly smooth muscle here Terminal Bronchioles - lots of smooth muscle in smaller bronchioles *this smooth muscle is acted on by the sympathetic NS, will relax upon stimulation to get more air in (think epi pen)*

Conduction Zone

Ventilation 1. Nose/Nasal Cavity: - air is being filtered, warmed, humidified, smelling (olfactory bulbs located) - contains respiratory epithelium with cilia 2. Pharynx: - upper naso-pharynx (air only with respiratory epithelium) - Eustachian tube - connects to ear - oropharynx (air and food) - laryngopharynx (epiglottis prevents aspirations) 3. Larynx - all cartilage a) epiglottis - helps prevent choking (aspirations) into trachea (keeps food in esophagus) b) thyroid cartilage (vocal cords) c) air only - keeps trachea open 4. Trachea - rings of cartilage and bands of connective tissue membrane - some muscle in the middle - the esophagus is behind trachea so rings of cartilage ensures airway is held open and doesn't collapse every time you swallow food

Regulation of Ventilation Rate

Ventilation rate is based on a need to regulate pH - equilibrium for the tissues pushes to the right (because tissues are always generating CO2; think Le Chatlier's) - equilibrium shifts to left in lungs due to CO2 always being pushed away

Gross motor control

allow for power, mass action (run/jump) - fewer motor units, but motor units are large in size, more cells, less neurons - will have large size of motor units but less of them - generates large amounts of force ex: back muscles, leg muscles, some arm muscles *few large motor units*

Osteoclasts

are activated by PTH to break down bone - clasts carry Ca2+ from bone to raise [Ca2+] in blood - when activated they break down solid hydroxyapatide into liquid

Which of these proteins binds calcium in smooth muscle cells? A. Myosin B. Troponin C. Actin D. Calmodulin

calmodulin binds calcium in smooth muscle cells. Instead of using the troponin-tropomyosin complex to bind calcium and facilitate actin-myosin interaction (as seen in striated muscle), calcium ions bind to calmodulin. This in turn activates myosin light-chain kinase (MLCK) to phosphorylate the myosin and enable it to bind actin. Myosin and actin are found in all muscle types, though their arrangement differs in striated and smooth muscle.

major tissue types

epithelial - lining muscle nervous connective - cells in a matrix

Which of these is the primary source of calcium ions in smooth muscle? A. Intracellular space B. T-tubules C. Sarcoplasmic reticulum (SR) D. Extracellular space

extracellular space. - The sarcoplasmic reticulum is poorly developed in smooth muscle cells. As a result, they rely primarily on extracellular calcium to mediate contraction via calcium binding to calmodulin. There is some calcium stored in the SR that can be released when a smooth myocyte is depolarized, however, this is a significantly smaller amount compared to what enters the cell via calcium channels. The intracellular space is always low in calcium. T-tubules do not store calcium; they are responsible for propagating surface depolarization into myocytes.

Respiratory Zone

gas exchange takes place in alveolus; type I cells form walls of the alveoli Type I cells: important for gas exchange between air we breathe and blood - thin and flat enough for air to be exchanged inside the alveolus and blood that is flowing around in capillaries Type II cells: reduce surface tension inside alveolus - makes breathing easier - alveoli produce surfactant don't appear until 33 weeks of gestation (7-8months) Alveolar ducts (made entirely of alveoli) leads into alveolar sacks (=many alveolus); tube leading into alveolar ducts is respiratory bronchioles (contains some alveoli) - this connects to terminal bronchiole

Bicarbonate Buffer System

hypoventilation (acidosis) = too little breathing so CO2 levels increase, causing H+ (right shift) to increase, this decreases pH hyperventilation (alkalosis) = too much breathing so CO2 levels decrease, causing H+ to decrease (left shift), making pH increase H2CO3 (carbonic acid) and HCO3- (bicarbonate) acid + weak base are two components in the buffer system that is utilized in the bloodstream - the H2CO3 breaks down into a proton (H+) and a bicarbonate ion, lowering the blood pH. It is now transported to the lungs. Summary: Carbonic anhydrase is an enzyme that balances the pH of the blood and enables the breathing out of carbon dioxide. carbonic anhydrase enzyme found in kidneys and PCT/DCT

Parathyroid Hormone (PTH)

increase [Ca2+] in the blood; released from parathyroid gland - released due to low blood Ca2+ - decreases Ca2+ in bone (increases resorption in bone) - this increase Ca2+ in intestines (increases absorption of Ca2+), increases reabsorption in kidneys - stimulates osteoclast activity - stimulates conversion of vitamin D into calcitrol (indirectly - via calcitrol - increases calcium absorption; kidney does this)

Which of the following is NOT true of the sarcoplasmic reticulum (SR)? A. It contains ligand-gated Ca2+ channels as well as Ca2+-ATPase transporters. B. It functions in calcium sequestering, storage and release. C. It is a type of smooth endoplasmic reticulum. D. It functions in regulation of skeletal muscle contraction.

it contains ligand-gated Ca2+ channels as well as Ca2+-ATPase transporters. The sarcoplasmic reticulum is a type of smooth endoplasmic reticulum - It functions in calcium sequestering, storage and release - therefore also in skeletal muscle contraction - However it contains voltage-gated Ca2+ channels (and Ca2+-ATPase transporters), not ligand-gated channels

Which of the following blood vessels carries blood with the highest PCO2? A. Pulmonary vein B. Pulmonary artery C. Renal artery D. Aorta

pulmonary artery. The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs, so it carries the blood with the highest amount of carbon dioxide. The pulmonary vein carries oxygen-rich, CO2-poor blood from the lungs to the left atrium (pulmonary vein is wrong), the aorta carries this same oxygen-rich, CO2-poor blood to the body (aorta is wrong), and the renal artery carries oxygen-rich, CO2-poor blood to the kidneys (renal artery is wrong).

Calcitonin

released from thyroid due to high blood calcium (tones down blood calcium) - increases Ca2+ in bone (increases bone desposition) - decreases Ca2+ in intestines (decreases absorption) - decreases Ca2+ in kidneys (decreases reabsorption) - inhibits osteoclast activity

Respiratory Zone contents (3)

respiratory bronchioles (RZ) alveolar ducts (RZ) alveoli (RZ)

What is the primary source of nutrition for the cartilage of the knee joint? A. Blood supply to the cartilage of the knee B. Lymphatic fluid C. Blood supply to the muscles that support the knee D. Synovial fluid

synovial fluid. - Cartilage is avascular; it does not have a blood supply. This is true of all joints in the body; none of them have a dedicated blood supply. As a result, nutrients and reparative substances can only reach articular cartilage of any joint via the synovial fluid, the fluid that bathes the joint. The cartilage within a joint is also unable to take advantage of blood supply to the muscles supporting the joint. Lymphatic fluid helps to clear excess fluid from the soft tissues of the body and return it to the circulation; it does not help to nourish cartilage.

All of the following are true regarding the innervation of skin by the autonomic nervous system EXCEPT: A. the sympathetic nervous system causes increased sweating. B. postganglionic sympathetic neurons that innervate sweat glands release acetylcholine. C. the skin does not receive parasympathetic innervation. D. the sympathetic nervous system causes dilation of blood vessels in the skin.

the sympathetic nervous system causes dilation of blood vessels in the skin. The sympathetic nervous system mediates the "fight or flight" response and causes increased sweating (to accommodate increased heat production from muscle activity, "the sympathetic nervous system causes increased sweating" is true and can be eliminated) and constriction of blood vessels in the skin (so that blood is shunted to the skeletal muscles, which are working overtime, "the sympathetic nervous system causes dilation of blood vessels in the skin" is false and the correct answer choice). The skin only receives sympathetic innervation ("the skin does not receive parasympathetic innervations" is true and can be eliminated). Answer "postganglionic sympathetic neurons that innervate sweat glands release acetylcholine" is actually true (and can be eliminated): The innervation of sweat glands is one exception to the rule that postganglionic sympathetic neurons only secrete norepinephrine.