Review #5

Question 1

Sinoatrial (SA) Node

Answer 1

1° PACEMAKER: In wall of right atrium; generates electrical signal (action potential) that is propagated through cells of atria via intercalated discs/ gap junctions, stimulating walls of both atria to contract = atrial systole (top to bottom) to push blood into ventricles

Question 2

Atrioventricular (AV) Node:

Answer 2

In lower wall of right atrium/ septum between atria; receives electrical signal from SA node (signal cannot pass directly to ventricles due to connective tissue -anchors valves etc.- between atria and ventricles); delays/ sends electrical signal slower to allow ventricles to fill with blood from atria before contracting, maximizing blood flow; AV node sends signals down Bundle of HIS (ventricular septum) to apex through conducting fibers (Purkinje fibers) and ventricles contract = ventricular systole (bottom up) to push blood out of heart into arteries
(aorta and pulmonary arteries)

Question 3

Pacemakers and the Cardiac Cycle (events in one complete heartbeat)

Answer 3

After EVERY contraction of the heart, there is a (relatively) long period of time (refractory period) where the heart is insensitive to stimulation (diastole), allowing heart to passively fill with blood and prevent tissue from becoming fatigued (able to contract entire life)

Question 4

ESSENTIAL NUTRIENTS

Answer 4

Cannot be synthesized by body so must be included in diet:

Question 5

Some amino acids

Answer 5

lack of essential aa’s can cause protein deficiency malnutrition = muscle loss, lack of blood plasma proteins, abdominal swelling, lethargy, physical and/ or mental retardation, no menstruation; some aa’s can be conditionally essential (pregnancy/ infancy)

Question 6

Some vitamins

Answer 6

organic compounds important in metabolic processes; from other organisms (especially plants); only need small intake

Question 7

Vitamin C/ Ascorbic acid:

Answer 7

essential in humans; immune system function, collagen and lipoprotein production, acts as an antioxidant; Deficiency = scurvy (symptoms = skin discoloration/ bruising, hemorrhaging, anemia, dental issues, exhaustion/ fatigue, swelling of joints)

Question 8

-Vitamin D

Answer 8

aids in bone formation/ repair, and aids in bone mineralization (aids in Ca2+/ phosphorus absorption which help bones mineralize); lack of vitamin D leads to lowered Ca2+, which causes rickets in children (growth plates do not mineralize/ thick bones/ decreased height/ bowed legs); causes osteomalacia in adults (soft/ weak bones)

Question 9

PKU -goes along with essential nutrients

Answer 9

autosomal recessive disorder; inability to break down phenylalanine into tyrosine (no phenylalanine hydroxylase enzyme) = mental/ developmental deficiencies, seizures

Question 10

Some unsaturated fatty acids

Answer 10

omega 3 and omega 6

Question 11

Some minerals

Answer 11

inorganic elements in ionic form; used in long-term structures/ molecules (Ca2+ in bones/ Fe3+ in hemoglobin) and function as electrolytes (Na+ and Ca2+ in muscle contraction; Na+, K+, Ca2+, and Cl- in action potentials/ synaptic transmission); only small intake needed

Question 12

Appetite (desire to eat)

Answer 12

controlled by hypothalamus; responds to hormones/ nerve signals
Inhibitory (promote fasting = do not eat)
- Vagus nerve sends nerve signals to hypothalamus when stomach stretches/ distends = full
- Insulin from pancreas (high blood sugar)
- CCK from intestines (as chyme moves into intestine from stomach)
- Leptin from adipose (fat) tissue (more fat = more leptin = less eating)

Stimulatory (promote feasting = eat)
- Glucagon from pancreas (low blood sugar)
- Ghrelin from stomach (empty = feed me)

Question 13

Malnutrition

Answer 13

is caused by a deficiency, imbalance, or excess of nutrients in the diet
Caused by:
Improper intake of nutrients (too many = overnutrition or too few = undernutrition; can be due to social/ economic factors too)
-Obesity (leading to CHD/ type II diabetes) common in overnutrition
-Starvation/ wasting/ anorexia (too thin) or stunting (too short) common in undernutrition
Improper utilization of nutrients by body (illness/ disease/ hypothalamus disorder)

Question 14

Overweight/ obese individuals

Answer 14

overnutrition (larger portions, overeating, insensitivity to leptin) and decreased energy expenditure/ physical activity = higher BMI (body mass index) = mass (kg)/ height2 (m)

Question 15

Overweight/ obese individuals most likely to suffer from

Answer 15

Type 2 Diabetes and Hypertension

Question 16

Type 2 Diabetes

Answer 16

(excessive overstimulation of cells by insulin due to overeating/ eating larger portions of sugar-rich foods leads to insulin insensitivity/ cells become desensitized to insulin and blood sugar remains high = hyperglycemia)

Question 17

Hypertension

Answer 17

high blood pressure (consistently greater than 120/80 mmHg); more weight = faster heart rate to move blood; can be due to higher cholesterol/ plaque deposits in arteries (narrows arterial lumen/ decreases arterial diameter/ hardens arteries/ decreases arterial elasticity = atherosclerosis); high cholesterol is an indicator of CHD (coronary heart disease) and hypertension is often a precursor to CHD
Causes of Hypertension: fat deposition in arteries (narrower lumen),
plaque deposits in arteries (narrower lumen/ loss of elasticity),
high salt diet (more fluid retention in blood/ blood to pump), smoking (nicotine = vasoconstriction), certain medications, stress/ stress hormones (vasoconstriction), genetics
Consequences/ Effects of Hypertension: stroke, thrombosis/ blood clots, heart attack, heart failure, coronary heart disease (CHD)

Question 18

Fats/ cholesterol

Answer 18

non-polar, so transported in blood as lipoproteins. Two types:
1: Low Density Lipoproteins (LDL) - transport cholesterol from liver to body (↑ blood cholesterol)
2: High Density Lipoproteins (HDL) - transport cholesterol from body to liver (↓ blood cholesterol)

Question 19

The TYPE (and amount) of fat (fatty acids) a person eats every day affects the amount of cholesterol in the blood:

Answer 19

1: Saturated fats: ↑LDL levels = ↑BLOOD CHOLESTEROL
2: Trans fats: ↑LDL levels and ↓HDL levels = SIGNIFICANTLY ↑BLOOD CHOLESTEROL
3: Cis-polyunsaturated fats: ↑HDL levels = ↓BLOOD CHOLESTEROL levels

Question 20

CORONARY ARTERIES

Answer 20

supply oxygenated blood directly to the heart itself. IF there are high levels of LDL in the bloodstream, LDL particles form deposits in artery walls (including coronary arteries). Coronary heart disease (CHD) is the development of atherosclerosis in the coronary arteries, which can lead to heart attack and stroke.

Question 21

Starvation

Answer 21

severe restriction (deficiency) of energy/ nutrient intake; can lead to body breaking down OWN tissues for energy (fats = first because more energy/ do not disrupt osmotic balance/ homeostasis; muscles after fats to provide protein); if enough body tissue broken down = severe organ damage/ death

Question 22

Anorexia nervosa

Answer 22

severely limited food intake, can cause body to break down heart muscle (can cause death); as heart muscle weakens/ atrophies arrhythmias develop, blood flow is reduced, and blood pressure drops

Question 23

Energy in Food:

Answer 23

measured in calories/ kJ (1 calorie – the energy required to raise the temp of 1g H2O by 1oC = 4.18 Joules)

1: Carbohydrates: “quick energy”/ easier to digest and transport so body’s preferred energy source

2: Lipids (fats): store ~2x energy as other molecules but difficult to digest and transport so used for long-term energy storage in adipose tissue

3: Proteins: aa’s used to build muscle tissue and can be used in cellular respiration but metabolism more difficult as breakdown produces nitrogenous waste = urea in humans (removed by kidney)

Question 24

Determining energy content of food = Calorimetry/ Combustion

Answer 24

Calorimeter = vessel filled with known quantity and temperature of water
Known mass of food is burned (combustion) and heat transferred to water (increases temp). To determine energy content of food = Mass of water (g) x 4.2 (J/g℃) x Temp increase (℃)
Constants = mass of water, distance between food source and calorimeter, mass of food sample, starting temperature of water
Error often caused by heat loss to environment or incomplete combustion of food sample

Question 25

Gastric (Stomach) Secretions

Answer 25

1: Site/ smell of food triggers reflex response 2: Medulla sends signals to stomach via vagus nerve to gastric glands to secrete gastric juice (HCl + pepsin + mucus) 3: Food arrives in stomach/ distention 4: Stretch receptors signal medulla; sends signals via vagus nerve; (NERVOUS) causes gastrin secretion from endocrine cells in stomach 5: Gastrin causes sustained HCl release (parietal cells) and pepsin release (chief cells) 6: IF pH too low, gastrin inhibited by secretin (small intestine) and somatostatin (hypothalamus) (HORMONAL)

Question 26

Exocrine glands in the digestive system

Answer 26

liver, gallbladder, pancreas, salivary glands, intestinal glands, gastric glands

Question 27

Exocrine glands

Answer 27

secrete products through DUCTS to lumen of alimentary canal/ “gut” -Ducts arise from structures called acini. Each acinus is a single layer of secretory cells (held together by tight junctions/ surrounded by a basement membrane); release products (in vesicles) into lumen of duct. Secretory cells contain LOTS of ROUGH ER (protein synthesis), Golgi, and Mitochondria (material production/ exocytosis)

Question 28

Stomach acid

Answer 28

(HCl) secreted by parietal cells (under control of gastrin) - proton pumps in parietal cells pump H+ ions into lumen of stomach (combines with Cl- to create stomach acid = HCl); maintains low/ acidic pH (1.5-2); the more H+ ions the lower the pH (and vice versa) Functions of stomach acid: 1: Digestive = denature proteins/ breakdown macromolecules; activate pepsin/ proteases for protein digestion 2: Other = destroys pathogens

Question 29

H.pylori and stomach ulcers

Answer 29

bacterium H. pylori survives acidic conditions of stomach (secretes urease to raise pH and mucinase to degrade mucus lining); this causes inflammation and allows HCl/ pepsin to damage/ digest stomach wall = ulcer

Question 30

PPI’s (Proton Pump Inhibitors) and ulcers/ H. pylori infection

Answer 30

-Proton (H+) pumps create acidic (low pH) conditions in stomach -PPIs bind IRREVERSIBLY to proton pumps/ prevent H+ secretion into stomach lumen -LESS H+ = increased pH (less acid) and stomach ulcers heal

Question 31

Vibrio cholera infection and dehydration

Answer 31

V. cholera bacteria infect lining of intestines -Produce toxin that causes epithelial cells to pump ions (Cl-) into intestines -Water follows ions (by osmosis) = dehydration (and diarrhea due to excess water diluting feces)

Question 32

The structure of the cells of the epithelium of the VILLI (small intestine) are adapted to their function (absorption of monomers, vitamins, and minerals from digested food products) = MR. SLIM

Answer 32

- Microvilli = folded to increase surface area for absorption - Rich capillary network = decrease diffusion distance for absorption of nutrients and maintain high concentration gradient for rapid absorption of nutrients - Single layer of epithelial cells = decreases diffusion distance - Lacteals = absorb lipids - Intestinal glands = release digestive juices/ carrier fluids - Membrane proteins = facilitated diffusion (large/ polar molecules; glucose/ amino acids, fructose, vitamins, and minerals) and active transport (glucose/ amino acids)

Question 33

Food products not absorbed

Answer 33

= egested (BELCH - Bile pigments, Epithelial cells, Lignin, Cellulose, Human microflora)

Question 34

Fiber

Answer 34

cellulose/ lignin (“roughage”) Helps food move faster through digestive tract, absorbs water so keeps feces softer/ prevents constipation, lowers risk of colon cancer, reduces time of exposure to undesirable food chemicals/ time of contact between intestinal wall and food, lowers blood cholesterol and regulates blood sugar levels (slows rate of absorption)

Question 35

Sinusoid structure vs. Capillary Structure

Answer 35

-Sinusoids need to allow LARGER molecules to move into and out of the blood. Compared to “normal/ regular” capillaries, sinusoids have: - larger/ wider diameter, - larger fenestrations/ openings in the endothelium/ basement membrane, and contain Kupffer cells

Question 36

Blood Flow OUT of Liver

Answer 36

Hepatic vein (deoxygenated back to heart, lower toxins/ nutrients, higher urea) i. After filtering, detoxifying, and balance nutrient levels in the blood, liver sinusoids (liver capillaries) drain into a central hepatic vein, which carries “clean/ balanced” blood back to heart

Question 37

Blood Flow INTO Liver

Answer 37

Hepatic artery (oxygen-rich from heart) + Hepatic portal vein (nutrient rich but oxygen poor b/c from intestines) Hepatic arterioles (hepatic artery branches) and hepatic venules (hepatic portal vein branches) drain into sinusoids (capillary beds in liver) Each sinusoid contains Kupffer cells (phagocytic -break down red blood cells) and each sinusoid is lined with hepatocytes (one cell layer thick)

Question 38

Kupffer Cells

Answer 38

Engulf ruptured red blood cells (erythrocytes) through phagocytosis Break down hemoglobin into heme and globin Peptidases break down globin into individual amino acids (used to synthesize new proteins or deaminated to produce urea - aa’s NEVER STORED) Heme broken down into iron (stored as ferritin or carried to bone marrow to make new hemoglobin) and bilirubin (bile pigment) Jaundice = excess bilirubin in body/ blood (yellow skin/ yellow whites of eyes, dark urine, pale feces) caused by liver disease/ cancer, gall bladder/ bile duct obstruction/ stones, anemia, immature liver in newborns

Question 39

Hepatocytes

Answer 39

Store glucose (as glycogen under control of insulin) and release glucose (under control of glucagon) Synthesize plasma proteins (fibrinogen) and non-essential amino acids (using aa’s from hemoglobin breakdown and from intestines) Store nutrients (glucose as glycogen, Vitamin A, Vitamin D, ferritin/ iron, triglycerides, minerals, and cholesterol (excess converted to bile salts/ drain into bile ductules/ ducts) Detoxify harmful substances in the blood (alcohol, drugs, poisons, food preservatives etc.)

Question 40

Cardiac Muscle Structures and Functions:

Answer 40

Cardiac muscle cells function to transmit electrical impulses and cause contractions for the heart to beat. Cardiac muscle cell structure is adapted to this function: Branched/ Y-shaped Cells: Increases surface area of contact between cells so cells can synchronize/ coordinate contraction faster Intercalated Discs: Connect adjacent cells = easy transfer of electrical impulses between cells AND hold cells together so cannot separate/ pull apart (lots of mechanical stress) Gap Junctions: Form channels that allow continuous flow of cytoplasm between cells (ion passage for rapid propagation) Many Mitochondria/ Glycogen Granules/ Rich Blood Supply: Aerobic respiration (ATP) for continuous contraction Cardiac muscle cells are NOT fused together (like skeletal muscle fibers), so each one CAN contract on its own. Coordinated contraction necessary for regular heartbeats (irregular = arrhythmias/ fibrillation); coordination achieved/ controlled by “pacemakers” (SA node = primary, AV node = secondary, Bundle of HIS = tertiary)

Question 41

Thrombosis

Answer 41

A blood clot within a blood vessel -Occurs in arteries due to damage as a result of cholesterol/ plaque deposits (atherosclerosis) -Deposits significantly reduce diameter of blood vessel (leading to hypertension, which damages arterial wall/ causing inflammation, causing more plaques to build) -If plaque ruptures/ breaks endothelial wall, blood clot forms = thrombus (restricts blood flow even more) -If thrombus becomes dislodged (embolus) can cause blockage at another site (in coronary arteries = can cause heart attack; in brain = stroke)

Question 42

Coronary Heart Disease (CHD)

Answer 42

-Build up of plaque (atherosclerosis) in coronary arteries (supply oxygen-rich blood directly to heart muscle). CHD in coronary arteries = decreases amount of oxygen to heart muscle. -Risk factors for CHD (“A GODDESS”): Age (less elasticity in arteries as age increases); Genetics (high cholesterol/ hypertension); Obesity (increased blood pressure/ strain on heart); Diseases (diabetes etc.); Diet (increased fat/ LDL cholesterol, salt, alcohol); Exercise (lack of/ sedentary lifestyle); Sex (males = lower estrogen); Smoking (nicotine increases blood pressure - vasoconstriction)

Question 43

Blood pressure

Answer 43

force of blood on artery walls (systolic = higher number = pressure when ventricles contract; diastolic = lower number = pressure when ventricles relax); Average = 120/80 mmHg Measure using sphygmomanometer (blood pressure cuff): 1: Increase cuff pressure to block artery/ arterial blood flow 2: As release pressure, first sound is systolic pressure (pressure in artery> pressure in cuff; forces blood through) 3: When NO MORE sound = diastolic pressure (diastolic pressure > cuff pressure)

Question 44

Heart sounds

Answer 44

As heart beats, generates heart sounds and forces blood into arteries (generating blood pressure) “lub/ lup” “dub/ dup”; due to closing of valves (valves maintain one-way flow of blood through heart, close due to pressure changes/ differences in atria, ventricles, and aorta/ pulmonary arteries) First sound (“lub/ lup”) from closing of AV valves (between atria and ventricles) at beginning of ventricular systole (as ventricles contract, pressure greater than in atria; pressure causes AV valves to close - prevents backflow of blood into atria) Second sound (“dub/ dup”) from closing of semilunar valves (between ventricles and aorta/ pulmonary arteries) after ventricular systole (as ventricles relax, pressure greater in arteries, causes valves to close - prevents backflow of blood into ventricles)

Question 45

Heart sounds

Answer 45

As heart beats, generates heart sounds and forces blood into arteries (generating blood pressure) “lub/ lup” “dub/ dup”; due to closing of valves (valves maintain one-way flow of blood through heart, close due to pressure changes/ differences in atria, ventricles, and aorta/ pulmonary arteries) First sound (“lub/ lup”) from closing of AV valves (between atria and ventricles) at beginning of ventricular systole (as ventricles contract, pressure greater than in atria; pressure causes AV valves to close - prevents backflow of blood into atria) Second sound (“dub/ dup”) from closing of semilunar valves (between ventricles and aorta/ pulmonary arteries) after ventricular systole (as ventricles relax, pressure greater in arteries, causes valves to close - prevents backflow of blood into ventricles)

Question 46

Medulla oblongata (in the brainstem):

Answer 46

Chemoreceptors detect CO2 levels/ pH of the blood IF CO2 levels rise and pH ↓ (blood becomes more acidic): Medulla sends a signal through cardiac nerve to the heart, releasing neurotransmitter called noradrenaline/ norepinephrine; causes SA node to fire more frequently – speeds up heart rate/ rate of contraction As CO2 levels return to normal: Medulla sends a signal through vagus nerve to the heart, releasing neurotransmitter called acetylcholine; causes SA node to fire less frequently – slows down heart rate/ rate of contraction, returning heart to resting/ myogenic rate -Heart rate can be increased or decreased by the medulla (brainstem), and it can be increased by the hormone adrenaline (epinephrine) - “fight or flight” response/ stress/ excitation (preparation for “vigorous activity”)

Question 47

Electrical activity of cardiac cycle shown on ECG

Answer 47

electrocardiogram/ ECG trace) -In an ECG, x-axis = time, y-axis = electrical activity (millivolts). Each normal heart beat should follow the same sequence of electrical events (P, QRS, T): P wave: Atria depolarize due to stimulation from SA node (atria contract) QRS complex: Ventricles depolarize; AV node sends signals through Purkinje fibers (ventricles contract) - atria repolarize (but cannot “see”) T wave: Ventricles repolarize/ relax (diastole) R to R = ONE cardiac cycle/ one heartbeat ECG used to detect/ diagnose abnormal heart rhythms, such as fibrillation = uncoordinated/ unsynchronized/ irregular contraction of heart muscle (cardiac muscle cells contract independently)

Question 48

DEFIBRILLATOR

Answer 48

-IF heart experiencing atrial or ventricular fibrillation/ having arrhythmias, DEFIBRILLATOR used - electrodes placed on patient’s chest, sends electric shock into patient’s heart to depolarize cardiac muscle/ reset SA node so it can regain control/ reset sinus (normal) rhythm.

Question 49

artificial pacemaker

Answer 49

-IF SA node defective/ impaired, or heartbeat too fast/ too slow/ irregular, an artificial pacemaker is implanted to regulate heart rate. Contains battery and pulse generator and connects to heart via cables and wires. If pacemaker detects abnormal heart rhythm, produces electrical impulses to stimulate regular heartbeat and coordinate contraction between atria and ventricles