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Biology 13A – Test 4 Lecture Notes
Chapter 15 – Digestive System
A. Overview
a. Function: ingestion of food, digestion, absorption, elimination
b. Structure: alimentary canal is the tube that food goes through. (Fig. 15.1)
i. The wall is made from mucosal layer (innermost) that secretes mucous.
ii. A muscular layer helps in movement of food. Peristalsis is a wavelike
contraction. (Fig. 15.4c)
c. Accessory organs support the functions.
B. Organs and parts
a. Mouth (Fig. 15.5-15.8)
i. Tongue has taste buds to taste food. Very muscular to mix food with saliva and
swallowing.
ii. Palate forms the roof of the mouth. Involved in tasting and swallowing when the
tongue pushes against it.
iii. Teeth to chew food.
1. Primary are “baby teeth”, secondary are “adult” teeth.
2. Enamel is hard outside, dentin is similar to bone, pulp cavity contains
nerves and blood vessels.
iv. Salivary glands produce saliva. Saliva begins digestion. Lubricates food.
Amylase to breakdown starch. (Fig. 15.10)
b. Pharynx – epiglottis closes during swallowing, allowing food to go into esophagus only.
Choking occurs when food goes into trachea. (Fig. 15.6)
c. Esophagus – muscular tube to send food to stomach.
d. Stomach – stores food and also produces gastric secretions (Fig. 15.11)
i. Muscular pouch with gastric glands. Glands contain gastric pits where gastric
juices are secreted (Fig. 15.12). Gastric juice contains HCL, mucus, and digestive
enzymes
ii. Parasympathetic nerves stimulate gastric glands upon a food stimulus. (Fig.
15.13)
iii. Ulcers result from a breach in mucous.
e. Small intestine – most digestion and absorption occurs here.
i. Folded to increase surface area (villi). (Fig. 15.24)
ii. Microvilli are cilia on cells that increase surface area. (Fig. 15.26)
f. Large intestine – absorbs water and makes feces. (Fig. 15.27)
i. Appendix is made of lymphatic tissue. No function in digestion and prone to
infection.
ii. Colon cancer is common, especially in low fiber diets (too slow fecal
movement).
g. Accessory organs
i. Pancreas – supplies small intestine with pancreatic juice (neutralizes acid from
stomach and helps digestion). Pancreas also produces insulin. (Fig. 15.14)
ii. Liver – makes bile (breaks down fat). Liver also involved in blood glucose
regulation, protein production, storage of minerals, detoxification. Contains two
lobes (Fig. 15.16)
iii. Gall bladder – stores and releases bile to small intestine.
C. Nutrition
a. Macronutrients – needed in large amounts, energy sources (1/3 of each)
i. Carbohydrates – sugars, starches
ii. Lipids – fats, phospholipids, cholesterol
iii. Proteins – amino acids are needed to make our own protein.
b. Micronutrients
i. Vitamins – organic and help in enzyme function. Others may be antioxidants
(pick up free radicals like H2O2)
ii. Minerals – inorganic and help in enzyme function. Bone and teeth require
calcium.
c. The ideal diet keeps changing (Fig. 15.33)
i. Vegetarians need to think about amino acid complementation
d. Body weight – Body Mass Index (BMI) = weight (lbs) x 703/height (in)2 (Fig. 15.34)
i. Underweight < 19
ii. Normal 19-24
iii. Overweight 25-29
iv. Obese > 30
Chapter 16 – Respiratory System
A. Components (Fig. 16.1)
a. Nose – nostrils are openings lined with hair to filter particles
b. Nasal cavity – air is filtered and warmed. (Fig. 16.2)
i. Mucous moistens air, traps pathogens (Fig. 16.3)
ii. Cilia on epithelium move towards pharynx.
c. Pharynx – leads to larynx
d. Larynx (Fig. 16.4)
i. Made from muscle and cartilage. Leads into the trachea.
ii. Vocal cords – membrane controlled by muscles to produce voice. Open during
normal breathing (Fig. 16.5). Laryngitis is an infection of the vocal cords.
e. Trachea is made from cartilage. Leads to bronchi (Fig. 16.6, 16.7).
f. Bronchi are branched tubes of cartilage. Leads to lung.
g. Bronchioles are smaller branches of bronchi.
h. Alveoli is where gas exchange with circulatory system occurs.
i. Lobular sacs embedded in capillaries. (Fig. 16.9)
ii. Oxygen and carbon dioxide exchanged here (Fig. 16.10)
i. Lung (Fig. 16.11)
i. Surrounded by a pleural membrane to form a tight seal.
B. Breathing (Fig. 22.8)
a. Mechanism
i. Inspiration – inhalation. Diaphragm muscle contracts to pull on pleural
membrane. This draws in air like an accordion (Fig. 16.12). Maximal inspiration
requires pectoral and sternal muscles to contract. (Fig. 16.13)
ii. Expiration – exhalation. Diaphragm muscle relaxes and elastic recoil of lung
tissues pushes out air. Maximal expiration requires abdominal muscles to
contract (Fig. 16.14)
b. Respiratory volume and capacity (Fig. 16.15)
i. Tidal volume – amount of air entering (or exiting) during a single normal breath.
ii. Vital capacity – maximum amount of air that can be taken in (or blown out).
What is left in the lung is called residual volume.
iii. Total lung capacity – total amount of air that can fit in the lung (vital capacity
plus residual volume).
c. Control of breathing
i.
ii.
iii.
iv.
Respiratory areas in the brain are connected to respiratory muscles (Fig. 16.16)
Voluntary breathing is controlled by the ventral respiratory group. (Fig. 16.17)
Involuntary breathing is controlled by the dorsal respiratory group.
CO2 levels and acid levels are detected in cerebrospinal fluid at vagus nerve. This
triggers respiratory areas. Oxygen and emotions can affect breathing too.
C. Gas exchange
a. Diffusion at the lung. CO2 out, O2 in due to partial pressure differences. (Fig. 16.20)
a. O2 binds to hemoglobin specifically. It is released at tissues (Fig. 16.21)
b. CO2 binds to hemoglobin (23%), rest is dissolved in plasma or red blood cells. Dissolved
CO2 may be bicarbonate (HCO3-) (Fig. 16.22)
c. Carbon monoxide (CO) kills because it binds hemoglobin preventing oxygen binding.
Chapter 17 – Urinary System
A. Components
a. Kidneys  ureters  bladder  urethra (Fig. 17.1)
b. Kidneys
i. Function
1. Filters wastes from blood
2. Secretes blood hormones
ii. Structure (Fig. 17.2)
1. Renal medulla makes up central portions
2. Renal cortex makes up outer portions. Origination of functional units
called nephrons
3. Renal artery and vein transports blood to and from the kidney
4. Nephrons (Fig. 17.6)
a. Ducts: glomerular capsule  proximal convoluted tubule 
nephron loop  distal convoluted tubule  collecting duct
b. Kidney stones are mineralized deposits usually in the collecting
ducts (Fig. 17A)
c. Blood supply: afferent arteriole  glomerulus  efferent
arteriole  peritubular capillary system
B. Urine Formation
a. Urine = Glomerular filtration – tubular reabsorption + tubular secretion (Fig. 17.8)
b. Glomerular filtration (Fig. 17.10)
i. Blood pressure is greater than pressure from glomerular capsule so fluid moves
into it.
ii. The pressure can be regulated by sympathetic nerves or the enzyme renin which
activates hormones that increase pressure
c. Tubular reabsorption (Fig. 17.12)
i. Many substances, such as sodium, glucose, and amino acids, are pumped into
peritubular capillaries. Water then follows due to osmosis. (Fig. 17.13)
ii. Pumping is often active (against concentration gradient) and require ATP.
d. Tubular secretion (Fig. 17.14)
i. Substances such as hydrogen ion and potassium are pumped into the renal tubule
e. Regulation of urine concentration and volume
i. Aldosterone stimulates the distal convoluted tubule to reabsorb more sodium and
secrete potassium
ii. ADH (antidiuretic hormone) retains water in the body by reabsorption in the
distal convoluted tubule and collecting duct.
C. Urine Elimination
a. Bladder structure (Fig. 17.16)
i. Inner wall is folded and can allow for expansion
ii. Trigone is a triangular structure which opens at the ureters and forms the opening
of the urethra.
iii. Detrusor muscle is involved in urination (micturition)
b. Micturition
i. Requires contraction of detrusor muscle and muscles of the abdomen and pelvis.
Requires relaxation of sphincter muscles below the bladder.
ii. As bladder fills and stretches, receptors signal to micturition reflex center in the
spinal cord. The micturition reflex center stimulates the detrusor muscle giving
the sense of urgency.
iii. Sphincter muscles are under voluntary control so urination can be controlled.
Chapter 18 – Water Balance
A. Fluid Balance
a. Distribution (Fig. 18.1)
i. Intracellular – inside cells (63% of fluids here). High NaCl (Fig. 18.2)
ii. Extracellular – outside cells (37% here). High potassium
iii. Forces that allow movement (Fig. 18.3)
1. Osmotic pressure
2. Hydrostatic (blood) pressure
b. Water
i. Intake by drinking, eating, and metabolism (Fig. 18.4)
ii. Output by urine, evaporation, feces. Can be controlled by ADH
iii. Disorders
1. Dehydration
a. Output exceeds intake
b. Symptoms are dry skin, mucous membranes, mouth. Can lead to
hyperthermia. Affects older and younger people more.
2. Water intoxication
a. Intake greatly exceeds output.
b. Coma can result from swelling in the brain.
B. Electrolyte Balance
a. Intake by eating and drinking, output by sweating and urine formation
b. Regulation of output - aldosterone signals uptake of sodium and secretion of potassium in
renal tubules. (Fig. 18.5)
c. Imbalances
i. Sodium
1. Hyponatremia – low sodium concentration. Caused by prolonged
sweating, vomiting, diarrhea, adrenal disease (low aldosterone), water
intoxication. Results in swelling in the brain.
2. Hypernatremia – high sodium concentration. Caused by fever, diabetes.
Results in CNS problems.
ii. Potassium
1. Hypokalemia – low potassium. Caused by excess aldosterone production,
diuretic drugs, kidney problems. Results in muscle weakness, paralysis,
respiratory and circulatory problems.
2. Hyperkalemia – high potassium. Caused by similar conditions to
hyponatremia. Results in circulatory and respiratory problems.
C. Acid-Base Balance
a. H2O  H+ + OHb. Sources of Hydrogen Ions (Fig. 18.6)
i. Carbonic acid from respiration
ii. Lactic acid from fermentation
iii. Acids from lipid, protein, and nucleic acid breakdown
c. Buffers
i. Regulate pH by accepting/releasing hydrogen ions
ii. Examples
1. Bicarbonate buffer: H+ + HCO3- ↔ H2CO3
2. Phosphate buffer: H+ + HPO42- ↔ H2PO4d. Medullary Respiratory Center
i. Regulates hydrogen ion by controlling breathing rate. Acts when buffers are
overworked (Fig. 18.8)
ii. Affects bicarbonate buffer reactions: H+ + HCO3- ↔ H2CO3 ↔ H2O + CO2
e. Imbalances (Fig. 18.9)
i. Acidosis
1. Respiratory acidosis – when ventilation is hindered. E.g. obstruction of
airways, decreased breathing. (Fig. 18.10). Results in CNS depression.
2. Metabolic acidosis – due to non-respiratory byproducts. E.g. kidney
failure, diabetes (Fig. 18.12).
ii. Alkalosis
1. Respiratory alkalosis – due to hyperventilation. Caused by anxiety,
poisoning, high altitude, fever. (Fig. 18.13) Results in overstimulation of
nerves.
2. Metabolic alkalosis – loss of gastric juices by vomiting or antacids or
other drugs. (Fig. 18.14)
Chapter 19 – Reproductive System
A. Male reproductive system
a. Testis  epididymis  vas deferens  urethra (Fig. 19.1)
b. Semen contains sperm and fluid from seminal vesicles, prostate, and bulbourethral
glands.
c. Testis
i. Seminiferous tubule produces sperm (Fig. 19.2).
ii. Spermatogenesis: 4 sperm produced from two cell divisions of spermatogonium.
Cells are released into lumen of seminiferous tubules (Fig. 19.4)
iii. Sperm (Fig. 19.3)
1. Head has nucleus and acrosome (contains enzymes to dissolve layers
outside the egg).
2. Midpiece is loaded with mitochondria.
3. Tail is a flagellum
d. Accessory organs
i. Seminal vesicles – secretes fructose and prostaglandins in an alkaline fluid
ii. Prostate gland – secretes alkaline fluid that also helps sperm motility
iii. Bulbourethral gland – secretes lubrication for intercourse
e. Hormone regulation is a simple negative feedback loop (Fig. 19.6)
i. GnRH LH + FSH  sperm --| GnRH, LH, FSH
B. Female Reproductive system
a. Ovary  uterine tube  uterus  vagina (Fig. 19.7, 19.11)
b. Ovary (Fig.19.9)
i. Oogenesis: divisions produces one is egg and 2-3 polar bodies (Fig. 19.8).
ii. Follicle houses oocyte.
iii. Egg matures and is released. Fimbriae draws egg into uterine tube.
iv. Follicle becomes a corpus luteum after release of egg.
c. Hormone regulation is on a monthly cycle menstrual. (Fig. 19.13)
i. FSH and LH cause follicle development and ovulation. Estrogen helps develop
female characteristics. Progesterone and estrogen maintain uterine lining.
ii. Estrogen produced by growing follicle causes spike in FSH and LH causing
ovulation.
iii. Corpus luteum produces progesterone and estrogen which maintain uterine
lining.
iv. If no pregnancy, then corpus luteum degrades  less E and P uterine lining
sloughs off (menstruation).
v. If pregnancy, then HCG from the placenta keeps corpus luteum alive, uterine
lining maintained.
C. Copulation
a. Male
i. Erection – arteries dilate, veins collapse in penis. cGMP allows blood flow into
erectile tissue. Viagra prevents cGMP breakdown.
ii. Ejaculation – stimulation of nerve tissue in penis causes movement of sperm
from epididymis. Semen is mixed and contractions at base of penis force semen
out. 300-400 million sperm.
iii. Orgasm is ejaculation and arousal of pleasure centers in brain.
b. Female
i. Erection – similar to males but in labia. Clitoris contains nerve center.
ii. Lubrication – vestibular glands secrete mucous into vagina.
iii. Orgasm – contractions in vagina, uterus, and uterine tubes can help transport
sperm.
D. Birth Control (Fig. 19.15)
a. Temporary
i. Withdrawal and rhythm methods are not effective
ii. Barrier methods
1. Prevent entry of sperm. Condoms, cervical caps, spermicide etc.
2. Block implantation - IUD is a shield that blocks embryo from uterus
iii. Hormone regulation
1. “The Pill” – continuous supply of estrogen and progesterone prevents
ovulation, lowering near end of cycle forces menstruation. Others:
norplant, depoprovera.
2. “Morning after pill” causes menstruation, even with implantation.
b. Surgery (Fig. 19.16)
i. Vasectomy – in males. Vas deferens are cut and tied. Can be reversed. Safer
than:
ii. Tubal ligation – in females. Uterine tubes are tied. Permanent.
Chapter 20 – Development
A. Fertilization (Fig. 20.2)
a. Occurs in the oviduct.
b. Sperm releases enzymes from acrosome which dissolves zona pellucida.
c. Head of sperm fuses with membrane and nucleus enters.
d. Egg membrane and zona pellucida hardens to prevent other sperm from entering.
e. Meiosis in egg completes and the two nuclei fuse.
B. Prenatal development
a. In the first week zygote will divide rapidly and form a hollow ball (blastocyst) but not
increase in size. (Fig. 20.4)
b. Implantation occurs at 1 week. Placental development begins (Fig. 20.5)
c. Placenta (Fig. 20.7, 20.9)
a. Forms from chorion which produces HCG to maintain estrogen and progesterone
to maintain uterus and stimulate mammary glands.
b. Exchanges materials between mother and fetus.
i. No blood exchange
ii. Materials exchanged at capillaries of chorionic villi. Wastes and carbon
dioxide out, nutrients and oxygen in. (Fig. 20.12)
d. Amnion with amniotic fluid surrounds embryo. Umbilical cord connects placenta to
embryo.
a. Amniocentesis involves taking amniotic fluid and performing a karyotype to
analyze chromosomes (Fig. 20C, 20.19)
e. Fetal circulation (Fig. 20.15)
a. Fetal hemoglobin binds to oxygen better than adult hemoglobin
b. Blood from umbilical cord travels through the liver.
c. Lungs are nonfunctional and blood bypasses pulmonary circuit by passing
directly from the right atrium to the left atrium.
C. Birth (Fig. 20.16)
a. Uterine muscle stretching as fetus grows causes contractions.
b. Positive feedback loop: contractions cause oxytocin to be released, which causes more
contractions. Dilation of cervix also releases oxytocin.
c. Contractions finally expel baby.
d. Afterbirth (placenta and uterine lining) follows shortly.
e. Circulatory system shifts to being independent of the mother (Fig. 20.18)