Digestive, Urinary, Skeletal, Muscular, and Developmental Systems Flashcards
Alimentary Canal
Muscular tube that begins at the mouth and ends at the anus.
Peristalsis
Rhythmic contractions that push food down the alimentary canal.
Journey of food through the organs
Food goes from the mouth, to the esophagus, stomach, small intestine, large intestine/colon, rectum.
Accessory Organs of the digestive system
- Organs that play a role in digestion but aren’t part of the alimentary canal
- Includes the teeth, tongue, salivary glands, liver, gallbladder, and pancreas
Exocrine Secretions
Released into body cavities such as the mouth or stomach or onto the body surface, such as digestive enzymes, saliva, or sweat.
Where is the pancreas located?
Tucked into a loop of small intestine on its left and extends to the right behind the stomach. Involved in the exocrine system.
The Mouth
- Ingestion of food is accomplished
- Teeth and tongue grind food into a lump (bolus) and salivary glands secrete saliva
- Saliva contains digestive enzyme amylase which helps to digest starch
The Stomach
- Acidic (1-2 pH) due to gastric glands secreting HCl. Helps to break up food and kill germs.
- Gastric glands secrete enzyme pepsin to help digest protein. HCl helps pepsin to work and activates pepsinogen into pepsin to digest proteins.
- The stomach secretes mucus to protect the lining from acid.
Gallbladder
Stores bile produced by the liver.
Liver
- Produces bile
- Stores glycogen, produces glucose, metabolizes fat, and detoxes the blood.
- Nutrient molecules are absorbed into the blood and brought to the liver for processing through portal veins.
Small intestine
- Site of the most digestion and absorption of nutrients
2. Bile is released to break down fats into chyme, but does not digest them.
Amylase
Enzyme that helps digest carbs
Protease
Enzyme that helps digest protein.
Lipase
Enzyme that helps digest fat.
Pancreas
- Secretes enzymes for each type of food for the small intestine
- Enzymes from the pancreas don’t work well in an acidic environment, so it secretes bicarbonate to neutralize acid in the intestines.
Where does digestion happen?
The stomach doesn’t really help with digestion, it mostly occurs in the small intestine.
Large intestine
- No digestion occurs, water is just reabsorbed
- Chyme becomes solid and turns into feces
- Large intestine contains a large amount of non pathogenic e. coli bacteria that prevents pathogenic bacteria from growing and supplies us with vitamin K.
6 kinds of nutrients
- Carbs, lipids, proteins, vitamins, minerals, and water
2. Vitamins, minerals, and water are small and don’t need digestion
Digestion
Breaking of large molecules into molecules small enough to cross cell membranes and enter the bloodstream. Small molecules are known as end products.
What are lipids broken down into?
Fatty acids and glycerol.
Vitamin A
- Needed to make retinal, a chemical necessary for sight
2. Deficiency would cause night blindness
Vitamin B
- Needed for cellular respiration and DNA replication
2. Deficiency can cause skin disorders, mental confusion, or anemia.
Vitamin C
- Needed to make a fiber in connective tissue (collagen)
2. Deficiency causes wounds that don’t heal or scurvy
Vitamin D
- Needed for calcium absorption
2. Deficiency causes weak bones and teeth or rickets
Vitamin E
- Needed to protect cell membranes from damage
2. Deficiency causes anemia
Vitamin K
- Needed for blood clotting
2. Deficiency causes easy bruising and excessive bleeding
Iron
- Mineral needed to make hemoglobin
2. Deficiency causes anemia
Calcium
- Mineral needed for strong bones and teeth
2. Deficiency causes rickets in children and osteomalacia in adults.
Iodine
- Mineral needed to make thyroxine
2. Deficiency causes decreased metabolic rate (hypothyroidism)
Main waste products of the body
- Urea from breakdown of amino acids, uric acid from breakdown of nucleic acids, creatinine from muscle matabolism
- All waste products other than water and CO2 are eliminated by the kidneys as urine.
What is the functional unit of the kidney?
The nephron
How does blood enter the kidney?
Through renal arteries that branch into capillaries.
Glomerulus
Knot of capillaries at the beginning of nephron, inside Bowman’s capsule.
Journey of blood through the nephron
- The capillaries of the glomerulus have pores, and blood pressure forces plasma through the pores, but cells and proteins stay behind.
- Plasma enters Bowman’s capsule as filtrate and travels along nephron tubules
- Substances the body needs such as glucose, water and amino acids are returned to the blood.
- Substances to eliminate remain in the tubules as urine
- Urine travels down the ureters and is stored in the bladder.
Reabsorption
Process of taking substances out of filtrate and returning them to the blood. Some are always reabsorbed, and some like water or ions are reabsorbed according to the bodies’ needs
Secretion
The process of taking substances out of the blood and adding them to the filtrate. Creatinine and some ions and drugs are always secreted.
Order of Nephron structure
Glomerulus, Bowman’s capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule, collecting duct.
Proximal convoluted tubule
Most reabsorption and secretion takes place here.
Loop of Henle
- A lot of water is reabsorbed
- Salt is transported out of filtrate and into tissues of the kidney to establish a concentration gradient
- The longer the loop, the greater the concentration gradient, and the more water can be reabsorbed
- The adrenal medulla is more concentrated than the adrenal cortex.
Distal convoluted tubule
- Specialized and regulated reabsorption and secretion
2. Aldosterone takes effect and increases sodium absorbed, and water follows.
Collecting Duct
- Receives filtrate from several nephrons. Urine concentration and water reabsorption are regulated
- Antidiuretic hormone takes effect and walls of the duct become permeable to water, so it can leave and move toward the salty center of the kidney.
- If ADH is present, water leaves and urine is more concentrated. Levels are high during dehydration.
How do the kidneys regulate blood pressure?
- Kidneys release enzyme renin that releases a chemical called angiotensin 2 and that constricts blood vessels when blood pressure is low
- A2 also increases secretion of aldosterone by the adrenal cortex to increase blood pressure.
Urethra
Carries urine to the outside of the body.
Skeletal System
Provides structure and support. All vertebrates have endoskeletons, while arthropods have exoskeletons.
Purpose of bones (4)
Support the body, protect soft organs, produce blood cells, and store minerals (calcium).
Cartilage
A rigid substance that is more flexible than bone. Found at the end of all bones and at joints, acting as a shock absorber. Some structures, such as the nose and external ear, are made of cartilage to give them flexibility and a definite shape.
Ligaments
Connect bones. Strong joints have multiple ligaments.
Tendons
Attach muscle to bone, and help to move the skeleton.
What is bone made of?
Cells embedded in a calcium- phosphate matrix.
Purpose of the muscular system (3)
Pull against bones to move them, support the body in an upright position, and protect internal organs.
Cardiac muscle
Found only in the heart. Involuntary muscle, can initiate its own contraction. Striated.
Smooth muscle
Found in hollow organs, like the stomach. Not striated, and is unvoluntary.
Skeletal muscle
Striated, voluntary, and attached to bones. Cells are long with many nuclei (multinucleate).
Which 2 proteins make up muscle?
Actin and myosin. Actin forms long, thin chains, and myosin bundles together to form thick fibers. The 2 proteins form sarcomeres.
Myofibril
Threadlike structure formed by sarcomeres. Bundle with cytoplasm, organelles, and nuclei to form a muscle cell.
Fasicles
Groups of muscle cells, which group together to form a whole muscle.
Z-lines
End of sarcomeres. Actin is attached, and myosin is found between actin filaments.
Sliding Filament Theory
- Theory of what happens when muscles contract
- Myosin binds to actin and drags it inward, toward the center of the sarcomere.
- Actin slides over myosin, dragging Z-lines, and actin overlaps.
- Myofibrils, muscle cell, and muscle get shorter, but length of actin and myosin don’t change.
Which neurotransmitter stimulates skeletal muscle?
Acetylcholine
Muscle contraction requires which mineral?
Calcium
3 layers of the skin
- Epidermis- thin surface layer of cells
- Dermis- thick layer of connective tissue with blood vessels, nerves, hair follicles, and glands.
- Hypodermis- layer of fat that protects and insulates
Purpose of the skin (5)
Protect from abrasion, heat loss, water loss, infection, and UV radiation.
What happens when body temperature rises?
- Receptors send information to brain
- Blood vessels in the dermis dilate so blood goes to the surface of the skin and heat can leave.
- Sweat glands are activated, and sweat evaporates, lowering body temperature.
What happens when body temperature falls?
- Blood vessels constrict, and bring blood closer to the core to retain heat.
- Sweat glands are inactivated
- Shivering is initiated. Muscle contraction generates heat.
How is sperm produced?
- The testes produce sperm and testosterone in response to luteinizing hormone. Testosterone is needed to produce sperm.
- Sperm are produced in seminiferous tubules in response to follicle stimulating hormone. Tubules merge to form the vans deferens duct, which connects to the urethra.
- Glands secrete fluid (semen) to provide nutrients for the sperm and carry it.
How are the uterus and ovaries controlled?
The ovaries are controlled by luteinizing hormone and follicle stimulating hormone. The uterus is controlled by hormones from the ovaries (estrogen and progesterone)
Menstruation
- Endometrium (uterine lining) is shed.
- First day of menstruation is day 1 of the menstrual cycle, and it lasts about 5 days.
- Estrogen and progesterone are low during this phase
- Occurs during follicular phase of the ovarian cycle
Proliferate Phase
- New uterine lining is built
- Controlled by estrogen
- Lasts from day 6 to day 13
- Occurs during follicular phase of the ovarian cycle
Phases of the uterine cycle
Menstruation, proliferative, secretory
Secretory Phase
- Uterine lining is maintained and enhanced
- Under control of progesterone
- Lasts from day 14 to day 28
- Occurs during ovulation and luteal phase of the ovarian cycle
Phases of the ovarian cycle
Follicular, ovulation, luteal
What is hcG?
Human chorionic gonadotropin, a hormone released by an embryo.
Follicular Phase
- Follicle Stimulating Hormone causes the development of a follicle in the ovary
- Estrogen is secreted and levels rise
- Lasts from day 1 to about day 13
- Occurs during menstruation and proliferative phase of the uterine cycle
What is a follicle?
Maturing oocyte and its surrounding cells, which grow and secrete estrogen.
Ovulation
- Oocyte is released into the fallopian tube
- Caused by surge of luteinizing hormone on about day 14
- Some of the follicle stays behind in the ovary and matures into the corpus luteum
- Occurs during the secretory phase of the uterine cycle
Luteal Phase
- The corpus luteum secretes mainly progesterone, and lasts about 2 weeks (from days 14-28) until it degenerates
- Estrogen and progesterone levels fall at the end, beginning the next cycle.
- Secretory phase of uterine cycle
What happens if the ovum that was released is fertilized?
- The embryo releases HcG, which prolongs the life of the corpus luteum, which can secrete more progesterone so the uterine lining never sheds
- HcG levels are high for 3-4 months, then the placenta secretes progesterone.
What happens after fertilization?
- A zygote is formed, a diploid cell with a full set of chromosomes.
- Cleavage-within 24-48 hours after fertilization, rapid mitosis with no growth. Travels to the uterus and becomes a solid ball of cells.
- Implants in the uterine lining. A blastocyst is formed, with the inner cell mass becoming the embryo and the outer ring becoming the placenta.
- The embryonic stage- lasts until the 8th week of development. Includes gastrulation and neurulation.
- Fetal stage- last until birth. The fetus grows and matures.
Gastrulation
Inner cell mass divides into 3 layers
- Endoderm- gives rise to the inner lining of the respiratory, reproductive systems, and others. Forms the liver and pancreas
- Mesoderm- gives rise to nonglandular organs such as bones, muscles, and heart
- Ectoderm- external structures such as skin and hair
Neurulation
Organs of the nervous system, as well as those of other systems, are formed. After this, the organs just mature.
Yolk sac
Surrounds the yolk of the egg and is food for a developing embryo. Not very important in humans.
Amnion
Membrane that surrounds the embryo and is filled with amniotic fluid, which acts as a shock absorber.
Allantois
Becomes the umbilical cord. In birds and reptiles, it’s a disposal site for solid wastes.
Chorion
Outermost membrane, forms embryo’s part of the placenta. Lines the inside of the shell in birds and reptiles.
