2025 Physiology Exam 3 Flashcards

Question

Gastrointestinal Smooth Muscle

Answer 1

Unitary (single-unit) smooth muscle Slow waves Spike potentials Muscle contractions

Answer 2

Syncronized Cells acting like Tissue

Answer 3

Peristalsis Rhythmic segmentation Tonic contraction

Answer 4

Stimuli that initiate peristalsis Distention - orad contraction with downstream receptive relaxation = “Law of the Gut” Irritation of gut epithelium Parasympathetic nervous system Function Myenteric plexus required Atropine (blocks Ach receptors) -peristalsis Congenital absence of plexus - no peristalsis

Answer 5

Chewing and swallowing Esophageal motility Gastric motility Small intestinal motility Large intestinal motility

Answer 6

Purpose of chewing Breaks cells—breaks apart indigestible cellulose Increases surface area—decreases particle size Mixes food with saliva Begins digestion of starches (-amylase, lingual lipase) Lubricates food for swallowing

Answer 7

Three stages Voluntary—initiates swallowing process Pharyngeal—passage of food through pharynx into esophagus Esophageal—passage of food from pharnyx to stomach

Answer 8

By Vagus Nerve

Answer 9

pH of stomach is ~1

Answer 10

Chyme must enter duodenum at proper rate. pH must be optimal (~7) for enzyme function (pancreas neutralizes the high stomach acid with bicarbonate) Slow enough for nutrient absorption. Immediately after meal—emptying does not occur before onset of gastric contractions.

Answer 11

Small intestinal motility contributes to digestion and absorption by: Mixing chyme—With digestive enzymes and other secretions Circulation of chyme—To achieve optimal exposure to mucosa Propulsion of chyme—In an aboral direction

Answer 12

Whether spike potentials and hence contractions occur depends upon neural and hormonal input. Nervous factors (PNS—stimulates/SNS—inhibits) Peristaltic reflex (Law of the Gut)—Mediated by ENS Intestino-intestinal reflex—Severe distention inhibits bowel Extrinsic nerves Gastroileal reflex—Meal stimulates. Ileocecal sphincter relaxes, ileal peristalsis increases. (gastrin, CCK, extrinsic nerves, ??).

Answer 13

Job is the absorption of water

Answer 14

Rectal distention initiates afferent signals that spread through myenteric plexus to descending and sigmoid colon, and rectum. This causes contractions that force feces toward anus.

Answer 15

Buffering - neutralize an acid

Answer 16

lipase breaks down fats Other one??? Majority the Parotid Functions of Saliva Lubrication and binding Solubilizes dry food Initiates starch digestion Oral hygiene: Flow of saliva decreases during sleep allowing bacteria to build up in mouth

Answer 17

Short-term storage reservoir Secretion of intrinsic factor Chemical and enzymatic digestion is initiated, particularly of proteins (proteins only) Liquefaction of food Slowly released into the small intestine for further processing.

Answer 18

Three major functions: Bacteriostatic Converts pepsinogen to pepsin Begins protein digestion (with pepsin)

Answer 19

Pepsinogen is an inactive, secreted form of pepsin . Acid converts pepsinogen to pepsin. Pepsin (35 kDa) converts more pepsinogen to pepsin. - Proteolytic enzyme - Optimal pH 1.8–3.5 - Reversibly inactivated >pH 5.0 - Irreversibly inactivated >pH 7–8 Pepsinogen Secretion Two signals stimulate secretion of pepsinogen. Vagal stimulation as mediated by acetylcholine Direct response to gastric acid

Answer 20

Proteolytic enzyme–Causes milk to curdle in stomach Milk retained in stomach and released more slowly Rennin secretion–Maximal first few days after birth. Replaced by secretion of pepsin as major gastric protease Secreted as inactive proenzyme (prochymosin) that is activated on exposure to acid

Answer 21

Youtube this more!!!

Answer 22

Only active once it leaves the Pancreas

Answer 23

Helps with enzyme Release???

Answer 24

Large intestine also contains crypts of Lieberkühn but there are no villi or enzymes. Crypts mainly secrete alkaline mucus Mucus secretion increased by parasympathetic stimulation

Answer 25

Digestion involves the breakdown or hydrolysis (addition of water) of nutrients to smaller molecules that can be absorbed in small intestine. Carbohydrates—Monosaccharides Proteins—Small peptides and amino acids Fats—2-monoglycerides and fatty acids

Answer 26

Luminal or cavital digestion: Occurs in lumen of GI tract Enzymes from salivary glands, stomach, pancreas Pancreatic enzymes can do all EXCEPT … Membrane or contact digestion: Enzymes on brush border of enterocytes

Answer 27

Starch digestion: Begins with a-amylase in saliva (5% digestion in mouth, up to 40% in stomach) Continues in small intestine with pancreatic amylase Final digestion occurs at brush border. Lactose and sucrose—Digestion only occurs at brush border.

Answer 28

Large Lipids to Lymph System through the Lacteals

Answer 29

Water moves into or out of gut lumen by diffusion in accordance with osmotic forces. Hypotonic chyme—Water is absorbed Hypertonic chyme—Water enters intestine Chyme is isotonic.

Answer 30

Gonadal tropics = affinity for gonads (FSH and LH) As FSH Rises = stimulates the egg ... Estradiol rises at Day 14 LH peaks = ovulation = expelling egg from the ovary Some woman feel this and its called = blood that is discharged when egg is expelled = mittelschmerz

Answer 31

Happens at the Follicular ... a follicle is maturing Day 4-14 happens at the ovary FSH is the main component here stimulating the follicle to maturity Follicle is secreting estrogen and goes back to pituitary to tell it the body doesn't need any more FSH

Answer 32

Primordial follicle matures to Primary follicle FSH and LH doing this work

Answer 33

Estrogen increases to create the negative feedback loop LH causes the ovulation

Answer 34

YOUTUBE THIS PORTION

Answer 35

Maturation of Gametes (sperm and egg) is meiosis Second part is only completed at fertilization

Answer 36

Know difference between Mitosis and Miesois

Answer 37

Estrogen coming out of Egg to lower/Stop FSH at the pituitary Corpus lutum = progesterone Day 14 follicle fills with blood?

Answer 38

Follicular Phase - stimulated by estrogen, up till ovulation, first 14 days when follicle is being matured Luteal Phase - after ovulation till menses, the follicle that was there is now filled up fat to form corpus lutum which releases progestogen, progestogen only produced during this phase

Answer 39

Estrogen being produced at the Follicular Stage Progestogens is produced by the corpus lutum during luteal phase

Answer 40

If no pregancy then the corpus lutum involutes and is called leutolysis??

Answer 41

? - the 11-2 days? YOUTUBE!!!

Answer 42

FSH comes from pituatry to tell ovary to produce estrogen/stimulates the follicle to mature Estrogen goes back to pituatry for negative feedback on FSH (released by maturing follicle) ... also goes to uterus to proliferate cells (basil layer) of uterus (days 5-15), estrogen tells the cells of the uterus to start dividing Follicular stage of ovary = proliferative stage of uterus Follicle matures and development of corpus lutum = increase in progesterone Progetersone causes endothelium to become global Adenomyosis With no pregnancy, corpus lutum dies (involution of it) = no more estrogen or progesterone Estrogen tells cervical secretion to be thin and watery Progesterone tells cervical secretion to be thick and vicious (to block the sperm) Progesterone works on Breasts

Answer 43

FSH coming and maturing a follicle = called follicular phase The follicle secretes estrogen as it matures ... proliferating the cells of the endometrium of uterus Proliferative phase = Follicular Phase LH is coming down and causes ovulation, blood enters follicle to release egg Luteal phase = follicle becomes corpus lutum and secrets progesterone and continues to grow endometrium If no pregnancy Corpus albacans = involuted corpus lutum = "dies" the endometrium thus sluffs off = bleeding and start of menstrual phase

Answer 44

Anterior Pituitary = 6/7 hormones controlled by Hypothalamus ... GnRH from Hypothalamus to release FSH (causes estrogen release) and LH (high level just before ovulation, caused by the high level of estrogen) FSH - causes follicular maturation (creating estrogen) LH - causes ovulation Ask this slide about the stimulation of FSH? thought estrogen told pituitary to not to produce more FSH

Answer 45

Know cell proliferation through protein

Answer 46

Breasts increase of lactiferous ducts and alveoli for milk production to feed baby

Answer 47

After 18 yos the "hormones" become pathologic Menopause is where ovaries become non-responsive to FSH and LH

Answer 48

Spermatogenesis is where the sperm is created Epididymis matures the sperm "teaches to swim" Vas deferens carry the sperm to world

Answer 49

Interstiutium contains Leydig Cells Sperm is developed works from outside to inside (see them with the tail)

Answer 50

First stage is Mitosis Second Stage Gametes divide by Meiosis 4 haploid cells Haploid = means half the set of chromosomes

Answer 51

Acrosomes contain lots of enzymes, used to cut thru the outer layer of the egg Motility Morphology Quantity

Answer 52

Made up of Seman (from seminal vesicles) and Seminal Fluid

Answer 53

Sertoli cells are also called nurse cells

Answer 54

Cryptochidism = failure for testes to descend

Answer 55

Leydig cells stimulated by LH and thus produce Test

Answer 56

LH goes to Leydig (testosterones) FSH to Sertolli (spermatogenesis)

Answer 57

last step in synthesis of Vitamin D... important for calcium uptake from gut Renin - produced by kidney, released to start the release of angiotensin (vasoconstriction) -aldosterone (increased sodium reabsorption) system (RAAS) is a hormone system that controls blood pressure, fluid balance, and electrolyte levels Filtration, Reabsorption and Secretion

Answer 58

Urea (from protein metabolism) Uric acid (from nucleic acid metabolism) Creatinine (from muscle metabolism) Bilirubin (from hemoglobin metabolism)

Answer 59

Hypocalcemia = Parathyroid Hormone = increase production of D3

Answer 60

Excrete acids (kidneys are the only means of excreting nonvolatile acids) Regulate body fluid buffers (e.g., bicarbonate, HCO3-) Increased H+... Body releases more HCO3-... combine to form H2CO3.... splits to form HO2 and CO2 to get rid of the extra hydrogen

Answer 61

Gluconeogenesis: Kidneys synthesize glucose from precursors (e.g., amino acids) during prolonged fasting

Answer 62

Endocrine Organ Renin-angiotensin system Prostaglandins Kallikrein-kinin system Control of extracellular fluid volume

Answer 63

Sodium and water Potassium Hydrogen ions Calcium, phosphate, magnesium

Answer 64

Has fenestrated capillaries The force behind it is hydrostatic pressure between blood and glomerular Proximal tubule - the glucose is reabsorbed from the ultrafiltrate 180 g/ml or more of glucose in the blood, the system is saturated, extra is spilling into urea = diabetes (will lead to polyurea) Anything not needed is Secreted

Answer 65

Filtration : Somewhat variable, not selective (except for proteins), averages 20% of renal plasma flow Reabsorption : Highly variable and selective most electrolytes (e.g., Na+, K+, Cl-) and nutritional substances (e.g., glucose) are almost completely reabsorbed; most waste products (e.g., urea) poorly reabsorbed. Secretion : Highly variable; important for rapidly excreting some waste products (e.g., H+), foreign substances (including drugs), and toxins

Answer 66

KNOW 180 liters/day each kidney

Answer 67

Whatever we reabsorb goes into the peritubular capillaries

Answer 68

GFR = 125 mL/min = 180 L/day (KNOW THIS) Plasma volume is filtered 60 times per day Glomerular filtrate composition is about the same as plasma, except for large proteins Filtration fraction (GFR/renal plasma flow) = 0.2 (i.e., 20% of plasma is filtered). Around capillaries = podocytes = visceral layer Around the glomurus as a whole = bowman’s capsule = parietal layer

Answer 69

Main pressure is hydrostatic of blood in the capillaries... push the filtration out

Answer 70

Bowman's Capsule pressure only changes with the disease

Answer 71

Is the determinant of GFR most subject to physiological control Factors that influence PG - Arterial pressure (effect is buffered by autoregulation) - Afferent arteriolar resistance - Efferent arteriolar resistance Hydrostatic pressure is the main determinant of filtration rate

Answer 72

Blood flow is directly proportional to the change in pressure Blood flow is inversely proportional to the resistance

Answer 73

High blood flow (~22% of cardiac output) High blood flow needed for high GFR Oxygen and nutrients delivered to kidneys normally greatly exceed their metabolic needs. A large fraction of renal oxygen consumption is related to renal tubular sodium reabsorption

Answer 74

As sodium reabsorption increases so does O2 consumption

Answer 75

Controlled by 2 Factors: Neurohumoral (hormones) Local (intrinsic within the kidneys)

Answer 76

Autoregulation of GFR and Renal Blood Flow Myogenic mechanism Macula densa feedback (tubuloglomerular feedback) Angiotensin II (contributes to GFR but not RBF autoregulation)

Answer 77

KNOW the basic formula: R= F-E

Answer 78

KNOW the basic formula

Answer 79

Glucose lost but reabsorbed (What part is it lost and reabsorbed in?) Threshold is 180

Answer 80

Glucose has this maximum (180 mg/min?)

Answer 81

Functionally similar in some ways to thick ascending loop*** Not permeable to water (called diluting segment)*** Active reabsorption of Na+, Cl−, K+, Mg++*** ~5% of filtered load of NaCl is normally reabsorbed. Contains macula densa ADH - released from anterior pituitary will result in water reabsorption in the late distal tubule

Answer 82

Hypocalcemia = parathyroid hormone = stimulate osteoclasts to reabsorb the matrix of bone for calcium = tells kidneys to synthesize more D3 (needed to absorb calcium in the small intestine) = tell the kidneys to absorb more calcium from the urine

Answer 83

Aldosterone produced in the adrenal cortex

Answer 84

Angiotensin Conversion Enzyme = ACE Inhibitor = decrease the amount of vasoconstriction by not enough of the enzyme to convert AT I to AT II

Answer 85

Osmolarity decreases because more fluid is reabsorb = decrease extracellular osmolarity

Answer 86

More fluid in the blood stream = decrease the osmolarity

Answer 87

Directly stimulates Na+ reabsorption Stimulates renin release Decreases GFR and renal blood flow (only a high levels of sympathetic stimulation)

Answer 88

Want a high dilute if dehydrated Want a Dilute urine when over hydrated

Answer 89

ADH works on Distal and Collecting tubules

Answer 90

Blood is dilute, decrease the amount of water going to blood to further dilute

Answer 91

Extracellular = interstitial and blood Intracellular = in the cell Must be equal

Answer 92

Want that 2300...

Answer 93

Lymphatics take away that 10% in interstitial

Answer 94

Can cause depletion

Answer 95

Endochondral ossification Intramembranous ossification Ossification is the conversion of soft tissue into bone, whether normal or abnormal (Long bone occurs at the epiphyseal plate)

Answer 96

Post Puberty = acromegalia = bones grow in width Pre Puberty = gigantism = bones grow in length

Answer 97

Cartilage model serves as the precursor of the bone… Examples of this are the bones that bear weight. Ossification is another word for osteogenesis and sometimes used for when bone is becoming calcified.

Answer 98

Begin with mesenchymal cells as well but need to make a cartilage matrix first. Mesenchymal cells under the influence of fibroblastic growth factors and bone morphogenic proteins, the mesenchymal cells express type II collagen at first. The mesenchymal cells then differentiate into chondroblasts, which produce the cartilage matrix. The chondroblasts contribute to the growth of the width of the bone. Interstitial growth attributes to bones growth in length. The matrix model is hyaline cartilage. The most outer portion becomes the periosteum, which was made by osteoblasts. This layer of the bone is very sensitive to pain. A distinctive cuff of bone occurs in the diaphyseal portions called the bony collar. Now the chondrocytes begin to hypertrophy and begin synthesizing alkaline phosphatase. The surrounding matrix goes through calcification.

Answer 99

Bone formed by differentiation of mesenchymal cells into osteoblasts... lay down the osteoid to form bone Examples of this type of bone are the flat bones of the skull, face, and clavicle. Intramembranous ossification is seen around the 8th week of gestation. As the osteoblasts secrete collagen (mostly type I), bone sialoproteins, and osteocalcin. Collagen requires Ascorbic acid (Vitamin C) as a cofactor for the essential enzyme Lysyl hydroxylase. This collagen then goes through a process called ossification which is calcifying the collagen. Upon calcification the osteoblasts become osteocytes within the canaliculi and eventually the lacunae. During this developmental phase the bone is also forming its own blood vessels (angiogenesis). (Powerpoint 1, slide 14 has an animation) KNOW WHERE RESERVE CALCIUM AND VITAMIN D COMES FROM

Answer 100

Hyaline cartilage: Type I collagen with mucopolysaccharide (organic glue) Hydroxyapatite crystals then precipitate onto the collagen Calcium and phosphate (PO4) salt then get deposited within the crystals to harden or ossify the bone

Answer 101

Like its close relatives, the fibroblast and the chondroblast, the osteoblast is a versatile secretory cell that retains the ability to divide. It secretes both type I collagen (which constitutes 90% of the protein in bone) and bone matrix proteins (BMPs), which constitute the initial unmineralized bone, or osteoid. The bone matrix proteins produced by the osteoblast include calcium-binding proteins such as osteocalcin and osteonectin; as well as multi-adhesive glycoproteins such as bone sialoproteins I and II, osteopontin, various proteoglycans, and alkaline phosphatase (ALP). Osteocalcin’s function is to bond hydroxyapatite to collagen. Vitamin-K helps osteocalcin do it’s bone bonding work. The collagen is then calcified. 70% of bone is inorganic salts, in dentin or cementum it is only 45%. Calcium is what causes ossification

Answer 102

Osteoclasts resorb bone tissue by releasing protons and lysosomal hydrolases into the constricted microenvironment of the extracellular space. Some, if not most, of the vesicles in the osteoclast are lysosomes. Their contents are released into the extracellular space in the clefts between the cytoplasmic processes of the ruffled border, a clear example of lysosomal enzymes functioning outside the cell. Once liberated, these hydrolytic enzymes, which include cathepsin K (a cysteine protease) and matrix metalloproteinases, degrade collagen and other proteins of the bone matrix.

Answer 103

Bone is regulated by mechanical forces but also, if not more so, by hormones. The two primary hormones are parathyroid hormone (PTH) from the parathyroid glands embedded in the posterior thyroid. The other is calcitonin which is released from C-cells (aka Parafollicular cell) in the thyroid. PTH acts on the bone to raise blood calcium levels to normal. Bone is the bodies reservoir for calcium. Calcitonin acts to lower blood calcium levels to normal. During child development and puberty the hormone somatotropin or growth hormone (GH) is a crucial hormone for the growth of bone and epiphyseal cartilage (growth plates). It acts directly on osteoprogenitor cells, stimulating them to divide and differentiate. Chondrocytes in epiphyseal growth plates are regulated by insulin-like growth factor I (IGF-I), which is primarily produced by the liver in response to GH. Hypocalcemia = osteoClast activation = PTH (hypercalcemic hormone/looking to raise blood calcium) Hypercalcemia = osteoBlast activation = Calcitonin (hypocalcemic hormone/looking to lower blood calcium)

Answer 104

PTH is released when calcium sensing receptors in the parathyroid gland sense a decrease in serum calcium. In the plasma…40% of the calcium is protein bound and 60% is not and thus is filterable by the kidneys. Only free, ionized calcium is biologically active. PTH is an overall calcium regulator. When secreted it will also make the kidneys stop secreting calcium and to make more Vitamin D. Vitamin D is essential for calcium absorption into the body. Hypovitaminosis D can result in hyperparathyroidism PTH also tells the intestines to absorb more calcium indirectly by stimulating Vit D3 production in the kidney. Stimulate osetoclasts to reabsorb bone Tells kidneys to increase intake of calcium Tells kidneys to produce more Vitamin D PTH inhibits renal phosphate reabsorption from the proximal tubule, which increases phosphate excretion. Phosphate and bone have inverse relationships in the body, as one increases the other decreases and vice versa. The renal reabsorption of calcium occurs in the distal tubules of the nephron

Answer 105

Parathyroid hormone (PTH) binds to receptors on osteoblasts, causing them to form receptor activator for nuclear factor kappa-B ligand (RANKL) and to release macrophage-colony stimulating factor (M-CSF). RANKL binds to RANK while M-CSF binds to its receptors on preosteoclast cells, causing them to differentiate into mature osteoclasts. PTH also decreases production of osteoprotegerin (OPG), which inhibits differentiation of preosteoclasts into mature osteoclasts by binding to RANKL and preventing it from interacting with its receptor on preosteoclasts.

Answer 106

Acts primarily to inhibit bone resorption. Does this by inhibiting the osteoclasts. Excreted by the C-cells (Parafollicular cells) in the thyroid in reaction to hypercalcemia. The more prolonged the hypercalcemia it decreases the formation of new osteoclasts. Minor effect on the calcium handling by the kidney and intestines.

Answer 107

Multi-Unit Smooth Muscle Present in iris, ciliary bodies, and vas deferens. Behave as separate motor unties. Has little or no electrical coupling between cells. Is densely innervated; contraction is controlled by neural innervation. Unitary (Single-unit) Smooth Muscle Is the most common type and is present in the uterus, GI tract, ureter, and bladder. Is spontaneously active (exhibits slow waves) and exhibits “pacemaker” activity, which is modulated by hormones and neurotransmitters. Has a high degree of electrical coupling between cells. Vascular Smooth Muscles Has both multi-unit and single-unit smooth muscle.

Answer 108

The is NO troponin; instead Ca2+ regulates myosin on the thick filaments. Average duration of action potential is 10 msec vs skeletal muscles 1 msec. Molecular basis for contraction: Ca2+-calmodulin increases myosin light-chain kinase.

Answer 109

Depolarization occurs: Opens voltage-gated Ca2+ channels and Ca2+ flows into the cell. Hormones and neurotransmitters may open ligand-gated Ca2+ channels in the cell membrane. They also directly release Ca2+ from the sarcoplasmic reticulum through inositol 1,4,5-triphosphate-gated Ca2+ channels. This increase in calcium binds to calmodulin. This complex binds to and activates myosin light-chain kinase. This myosin then phosphorylates myosin and allows it to bind to actin. The amount of tension produced is proportional to the intracellular Ca2+ concentration. A decrease in intracellular Ca2+ produces relaxation.

Answer 110

Powerpoint 1, slide 41 has great animation

Answer 111

AP depolarizes the sarcolemma (muscle cells membrane) which depolarizes the T tubules This changes a dihydropyridine receptor’s shape, which opens Ca2+ release channels (ryanodine receptors) in the nearby sarcoplasmic reticulum. The SR is a membrane-bound structure that stores calcium. Calcium floods into the intracellular space; this calcium binds to troponin C on the thin filaments. This allows tropomyosin to move out of the way so myosin can attach to actin. At first, myosin is attached to actin…adenosine triphosphate (ATP) attaches to the myosin which DETACHES the myosin from the actin. Myosin attaches to a new site on actin, which constitutes the power (force-generating) stroke. ADP is then released, returning myosin to its rigor state. This cycle repeats as long as Ca2+ is bound to troponin C. Each power-stroke or cross-bridge cycle “walks” the myosin further along the actin filament. Relaxation occurs when calcium goes back into the sarcoplasmic reticulum via Ca2+ -ATPase channels

Answer 112

Synaptic Cleft is more chemical than physical

Answer 113

Isometric = tension increases = muscle fibers stay same (Pushing against a wall) Isotonic = tension remains the same = muscle fibers shorten (DB Curl)

Answer 114

Have varicosities not motor neurons

Answer 115

The troponin complex is absent. (Calmodulin is very similar in structure.)

2025 Physiology Exam 3 Flashcards

Lectures 12-16: GI, Reproductive, Nephrology, Bone/Muscle