Anatomy Chapter 38 BIO Cheat Sheet by Sahasra M

- nutrients: substances in food that supply the energy and raw materials your body uses for growth, repair, and mainte­nance
- nutrients body needs: water, carboh­ydr­ates, fats, proteins, vitamins, minerals

- water makes up blood, lymph, and other bodily fluids
- water is lost during sweating when it evaporates to cool the body
- water vapor is also lost from the body with every breath you exhale & in urine
- humans need to drink at least 1 liter/per day
- dehydr­ation leads to problems with circul­atory, respir­atory, and nervous systems

- simple & complex carboh­ydrates are main source of energy
- simple carboh­ydrates or monosa­cch­arides disacc­harides are found in fruits, honey, & sugar cane
- simple carboh­ydrates do not need to be digested or broken down
- complex carboh­ydr­ates, or starches, are found in grains, potatoes, and vegetables
- complex carboh­ydrates need to be broken down into simple sugars before they can be used
- these molecules are broken down into complex carboh­ydrate glycogen
- sugars not immedi­ately used are converted to complex carboh­ydrate glycogen, which is stored in liver & skeletal muscles

- fiber contains complex carboh­ydrate cellulose
- bulk supplied by fiber helps muscles keep food and wastes moving through your digestive and excretory systems
- whole-­grain breads and many fruits and vegetables have fiber

- Fats are needed:
• to produce cell membranes, myelin sheaths
around neurons, and certain hormones
• to help the body absorb fat-so­luble vitamins
• to protect body organs and insulate the body
- fats are saturated or unsatu­rated
- single bonds between carbon atoms in the fatty acids -> saturated.
- most saturated fats are solids at room temper­ature (butter, animal fats)
- at least one double bond in fatty acid chain -> unsatu­rated
- unsatu­rated fats are usually liquids at room temper­ature
- vegetable oils have more than one double bond -> polyun­sat­urated
- recomm­ended 30% of calories from fat & 10& from unsatu­rated
- too much fat -> bp, heart disease, obesity, diabetes

- proteins supply raw materials for growth and repair of structures such as skin and muscle; have regulatory and transport functions
- ex: hemoglobin transports oxygen
- proteins are polymers of amino acids; body can synthesize only 12 of the 20 amino
acids used to make proteins & the other 8 amino acids are called essential amino acids; they must come from food
- animal products, including meat, fish, eggs, and milk, contain all 8 essential amino acids
- foods from plants, such as grains and beans, do not

- vitamins: organic molecules that help regulate body processes, often working with enzymes
- most vitamins must be obtained from food
- a diet lacking certain vitamins can have serious, even fatal, conseq­uences
- two types of vitamins:
• fat-so­luble
• water-­soluble
- fat-so­luble vitamins A, D, E, and K can be stored in the fatty tissues of the body
- body can build up stores of these vitamins for future use
- water-­soluble vitamins dissolve in water and cannot be stored in the body

- inorganic nutrients that the body needs, usually in small amounts, are called minerals
- ex: calcium, iron, magnesium
- calcium: major component of bones & teeth; iron makes hemoglobin
- calcium, sodium, & pottasium are required for normal functi­oning of the nerves

- food pyramid: grains, vegeta­bles, fruits, milk, meat and beans, fats, sugars, and salts
- need at least 30 minutes of exercise each day
- food label: inform­ation about nutrition.
- daily values are based on a 2000-C­alorie diet, and nutrient needs are affected by age, gender, and
lifestyle
- when you choose a food, it should be high in nutrition and low in Calories

- you need to eat food to obtain energy.
- energy in food is measured in Calories
- one Calorie = 1000 calories or 1 kiloca­lorie
- one calorie: amount of heat needed to raise the temper­ature of one gram of water by one
degree Celsius
- averag­e-sized female teen: needs about 2200
Calories a day
- averag­e-sized male teen: needs about 2800
Calories a day
- regular exercise = need more calories

- chewing begins mechanical digestion, which is the physical breakdown of large pieces of food into
smaller pieces
- the teeth cut, tear, and crush food into small fragments
- as the teeth cut and grind the food, salivary glands secrete saliva, which moistens food and makes it
easier to chew
- saliva helps ease the passage of food through the digestive system and also begins the process of
chemical digestion
- saliva contains amylase, an enzyme that breaks the chemical bonds in starches and releases sugars
- saliva also contains lysozyme, an enzyme that fights infection

- stomach acids sometimes damage the organ’s own lining, producing a hole in the stomach wall (peptic ulcer)
- most peptic ulcers are caused by the bacterium H. pylori.
- other digestive disorders include diarrhea and consti­pation

- chyme leaves the small intestine -> enters the large intestine or colone
- large intestine removes water from the chyme
- water is absorbed quickly, leaving undigested materials behind
- concen­trated waste material passes through the rectum and is eliminated from the body

- small intestine is adapted for the absorption of nutrients
- folded surfaces of the small intestine are covered with fingerlike projec­tions called villi
- cell surfaces of villi have more projec­tions called microvilli
- these provide an enormous surface area for the absorption of nutrient molecules
- slow, wavelike contra­ctions of smooth muscles move the chyme along this surface
- nutrient molecules are absorbed into the cells lining the small intestine
- most products of carboh­ydrate and protein digestion are absorbed into the capill­aries in the villi
- molecules of undigested fat are absorbed by lymph vessels

- as chyme is pushed through the pyloric valve, it enters the duodenum
- duodenum: first of three parts of the small intestine, and is where most digestive enzymes enter the intestine
- most chemical digestion & absorption of food occurs in the small intestine
- just behind the stomach is the pancreas
- during digestion, the pancreas:
• produces enzymes that break down
carboh­ydr­ates, proteins, lipids, and nucleic acids
• produces sodium bicarb­onate, a base that
neutra­lizes stomach acid so that these enzymes
can be effective
- assisting the pancreas is the liver, which produces bile
- bile dissolves and disperses droplets of fat in fatty foods -> enables enzymes to break down smaller
fat molecules
- bile is in the gallbl­adder

- food from the esophagus empties into the stomach
- the stomach continues mechanical and chemical digestion
- altern­ating contra­ctions of three smooth muscle layers churn food
- chemical digestion: the stomach lining has millions of gastric glands that release substances into the stomach
• some glands produce mucus (lubri­cates & protects stomach wall)
• other glands produce hydroc­hloric acid (makes stomach contents very acidic)
• other glands produce pepsin (enzyme that digests protein)
- pepsin and hydroc­hloric acid start protein digestion
- pepsin breaks proteins into smaller polype­ptide fragments
- other enzymes are denatured by stomach acid
- mechanical digestion: stomach contracts to churn fluids and food, gradually producing a mixture known as chyme
- after 1–2 hours, the pyloric valve between the stomach and small intestine opens and chyme
flows into the small intestine

- from the throat, the chewed food passes through the esophagus, or food tube, into the stomach
- food is moved along by contra­ctions of smooth muscle
- these contra­ctions (peris­talsis) squeeze the food through the esophagus into the stomach
- cardiac sphincter closes the esophagus after food -> passes into stomach

- digestive system: mouth, pharynx, esophagus, stomach, small intestine, and large intestine
- salivary glands, pancreas, and liver add secretions to the digestive system, and aid in digestion
- digestive system: help convert foods into simpler molecules that can be absorbed and used by the cells of the body

- every cell produces metabolic wastes
- the process where these wastes are eliminated is called
- skin excretes excess water & salts in the form of sweat; lungs excrete carbon dioxide
- kidneys also play a major role in excretion

- the kidneys: remove waste products from the blood, maintain blood pH, and regulate the water content of the blood & blood volume
- kidneys (either side of the spinal column near the lower back)
- a tube (ureter) leaves each kidney, carrying urine to the urinary bladder (saclike organ where urine is stored before excreted)
- blood enters kidney through renal artery
- kidney removes urea, excess water, & other waste products and passes them to ureter
- clean, filtered blood leaves the kidney through renal vein & returns to circul­ation
- renal medulla: inner part of kidney
- renal cortex: outer part of kidney
- functional units of the kidney are called nephrons
- nephrons are located in the renal cortex, except for their loops of Henle, which descend into the renal
medulla
- each nephron has its own blood supply: arteriole, venule, network of capill­aries connecting them
- each nephron releases fluids to a collecting duct -> leads to the ureter.
- blood enters a nephron through the arteriole -> impurities are filtered out and emptied into the collecting duct
- purified blood exits the nephron through the venule
- blood purifi­cation involves filtration and reabso­rption
- filtration (happens in glomer­ulus): passing a liquid or gas through a filter to remove wastes
- glomerulus is a small network of capill­aries encased in the top of the nephron by a hollow, cup-
shaped structure called Bowman's capsule
- fluid from blood flows into Bowman’s capsule
- materials filtered from the blood include water, urea, glucose, salts, amino acids, & some vitamins
- plasma proteins, cells, and platelets remain in the blood b/c they are too large to pass through
capillary walls
- reabso­rption: process in which liquid is taken back into a vessel
- almost 99% of the water that enters Bowman’s capsule is reabsorbed into the blood
- filtrate drains in the collecting ducts -> most water and nutrients have been reabsorbed into the blood
- remaining material (urine) is emptied into a collecting duct
- urine is primarily concen­trated in the loop of Henle (a section of the nephron tubule
where water is conserved & volume of urine minimized)
- kidney works -> purified blood is returned to circul­ation while urine is collected in the urinary
bladder
- urine is stored here until released from the body through a tube called urethra

- activity of kidneys is controlled by compos­ition of blood
- regulatory hormones are released in response to the compos­ition of blood
- you drink a liquid -> absorbs into blood through digestive system -> concen­tration of water in blood goes up -> rate of water reabso­rption in the kidneys goes down -> less water is returned to the blood & excess water is sent to urinary bladder to be excreted as urine
- if kidneys detect an increase in salt -> return less salt to the blood by reabso­rption
- excess salt the kidneys retain is excreted in urine -> mainta­ining the compos­ition of the blood

- humans have two kidneys, but can survive with only one
- if both kidneys are damaged by disease or injury -> kidney transp­lant, kidney dialysis
- kidney dialysis:
- Blood is removed by a tube & pumped through special tubing that acts like nephrons
- tiny pores in the tubing allow salts and small molecules to pass through
- wastes diffuse out of the blood into the fluid-­filled chamber, allowing purified blood to be returned to
the body