Chapter 16: The Body's Systems Flashcards
define homeostasis
- process of maintaining equilibrium around a set point
- there are often normal fluctuations but the body’s systems try to get back to the set point
define set point
- specific value of some aspect of the body or its cells
- body temperature, glucose, etc
describe the process of leaving and returning to homeostasis
- stimulus occurs in internal or external environment
- receptor (part of feedback mechanism) detects change
- receptor sends information to a control center
- control center relays signal to organ that is able to cause appropriate change
- system adjusts activities so the value moves back to the set point
define thermoregulation
- regulating heat
define ectotherms
- cold-blooded
- means “external temperature”
- animals that do not have internal control of their body temperature
- body temperature is similar to temperature of environment
- may exhibit behaviors to keep their bodies slightly above or below temperature of the environment
examples of behaviors ectotherms engage in to control their body temperature
- burrowing underground: get cooler
- resting in the sunlight: get warmer
which animals are ectotherms
- fish
- amphibians
- reptiles
- invertebrates
define endotherms
- warm-blooded
- means “internal temperature”
- animals that maintain a constat body temperature in the face of environmental changes
- can maintain higher level of activity because they can generate internal heat (optimal cellular processing even in cold environments)
which animals are endotherms
- mammals
- birds
adaptations in ectotherms to conserve or dissipate heat
- changes in behavior
- ex: desert animals seeking cooler areas during the day and warmer areas during the night
adaptations in endotherms to conserve or dissipate heat
- behavioral and physical adaptations
- insulation through thick fur/feathers or fat
- shivering to increase body heat
- sweating to cool body
what body systems are involved in thermoregulation
- circulatory system
- nervous system
what are the 2 ways that the circulatory system affects thermoregulation
- vasodilation
- vasoconstriction
describe how vasodilation affects body heat
- used when temperature rises to cool the body
- opening of arteries to the skin by relaxation of smooth muscles
- brings more blood and heat to the body surface where it is lost to the environment
describe how vasoconstriction affects body heat
- used when temperature falls to heat the body
- narrowing of blood vessels to the skin by contraction of smooth muscles
- reduces blood flow to peripheral blood vessels
- forces blood toward the core and vital organs
- conserves heat
define negative feedback
- stimulus causes changes to return the system to the set point
- most of body processes
- maintains homeostasis
define positive feedback
- driving a reaction forward
- ex: labor contractions
how does the nervous system affect thermoregulation
- head coordinator of regulating body heat
- temperature controlled in hypothalamus
- directs sympathetic nervous system to effect changes to shift body temperature to set point
how does the hypothalamus control thermoregulation
- maintains set point for body temperature
- causes vasodilation/vasoconstriction and sweating/shivering
what is countercurrent heat exchange
- unique to dolphins, sharks, bony fish, bees, and hummingbirds
- adaptation to circulatory system that allows animals to warm blood by returning it to the heart
- veins and arteries have heat transfer that warms blood before it goes to the heart and other organs
define osmoregulation
- process of maintaining salt and water balance across membranes within the body
examples of body fluids that need osmoregulation
- blood plasma
- fluid within cells
- interstitial fluid
define interstitial fluid
- fluid that exists in the spaces between cells and tissues of the body
what is fluid within and surrounding cells composed of
- water
- electrolytes
- non-electrolytes
define electrolytes
- compounds that dissociate into ions (such as salt) when dissolved in water
define non-electrolytes
- compounds that do not dissociate into ions in water
- ex: glucose
describe the semi-permeability of membranes of the body
- permeable to certain types of solutes and water
- impermeable to many solutes, especially those with charge
define thermodymanics
- study of energy and energy transformations
- governed by the laws of thermodynamics
define systems and surroundings in thermodynamics
- system: matter under study
- surroundings: everything outside the system
define open and closed system
- open: energy can be exchanged with it’s surroundings
- closed: cannot exchange energy with it’s surroundings
are biological systems open or closed
- open
- energy is exchanged with surroundings
where does excess water, electrolytes, and wastes go in the body
- transported to the kidneys to be excreted
- helps maintain osmotic balance
what happens if there is no mechanism to regulate osmotic pressure
- accumulation of toxic waste and water
does osmoregulation directly affect blood pressure
- yes
how is the excretory system involved in osmoregulation
- excretory system removes waste from the body through the skin as sweat, lungs as carbon dioxide, and urinary system as urine
what structures is the urinary system composed of
- kidneys
- ureter
- urinary bladder
- urethra
define kidneys
- pair of bean shaped organs located below the liver
- each contains millions of nephrons that filter metabolic waste from the blood, concentrate it, and form urine
define ureter
- tubes that carry urine out of the kidneys and empty into the bladder where urine is collected
define urethra
- tube that allows urine to flow out of the bladder and the body
describe how blood enters the kidney to be filtered
- blood enters from the aorta into the renal artery and then into the kidneys
- blood is distributed through smaller vessels in the kidney until it reaches nephrons
describe how blood leaves the kidney after being filtered
- blood collects and leaves through the renal vein which then joins the inferior vena cava
- water and ions are reabsorbed into the circulatory system
- waste is collected and leaves through the ureter into the bladder
how do animals obtain their nutrients
- consumption of other organisms
- must convert macromolecules to simple molecules required for maintaining cellular function
what are the two steps for converting food consumed to nutrients
- digestion (physical and chemical)
- absorption
describe the pathway of food through the digestive system
- begins in the mouth
- enters esophagus
- enters acidic stomach
- further breakdown in small intestine
- waste travels to the large intestine
where does digestion begin
- mouth/oral cavity
what is the pH of the stomach
- 1.5 to 2.5
what is the purpose of the stomach being acidic
- kills microbes
- breaks down food tissues
- activates digestive enzymes (pepsin)
what occurs to food in the small intestine
- bile from the liver and enzymes produced from the small intestine and pancreas continue breakdown
- smaller molecules are absorbed into the bloodstream through the small intestine lining
what occurs to food in the large intestine
- water is absorbed
- drier waste is compacted into feces
what types of digestion take place in the oral cavity
- physical: mastication (chewing)
- chemical: saliva enzymes
what does saliva include and what does each component do
- mucus to moisten food
- buffers to balance pH of food
- lysozyme enzyme for antibacterial action
- amylase enzyme to convert starches into maltose
- lipase enzyme produced in the tongue to break down fats
define bolus
- term for the mass of food that is created after chewing and wetting food in the oral cavity
- what gets swallowed
- moved by the tongue into the pharynx
describe how food moves through the esophagus
- smooth muscles undergo peristalsis: wave-like muscle contractions
- peristalsis is involuntary and unidirectional (moved in one direction)
- gastro-esophageal sphincter at the end of the esophagus opens in response to swallowing and the bolus enters the stomach
define sphincter
- ring-like muscles that form valves in the digestive system
- gastro-esophageal sphincter connects esophagus and stomach
- pyloric sphincter connected stomach and small intestine
where does a large part of digestion take place
- stomach
what digestive enzyme is in the stomach and what does it break down
- pepsin
- digests proteins
what types of digestion take place in the stomach
- physical: contraction and relaxation of smooth muscles
- chemical: enzymes (pepsin)
define chyme
- partially digested food/gastric juice mixture
define gastric emptying and the time it happens
- movement of chyme from stomach to small intestine through pyloric sphincter
- occurs 2-6 hours after a meal
why is only a small amount of chyme emptied into the small intestine at a time
- pH of stomach 2; pH of small intestine 7
- small amount released to neutralize pH gradually
what is the movement of chyme into the small intestine regulated by
- hormones
- stomach distension
- muscular reflexes affecting the pyloric sphincter
how is the lining of the stomach protected form pepsin activity and the acidic pH
- mucus layer in stomach protects underlying tissue
what does the small intestine do
- digestion of protein, fats, and carbohydrates is completed
- absorption begins
define villi and microvilli
- villi: finger-like projections on the surface of the small intestine lining, multiple epithelial cells folded up make a villi
- microvilli: on the surface of each epithelial cell
where is nutrients absorbed from digested food and released into the bloodstream in the small intestine
- epithelial cells
why are villi and microvilli important
- create many folds in the small intestine
- increase surface area and absorption efficiency
describe villi in a person with celiac disease
- villi are compressed down
- nutrients cannot be absorbed effectively
how big is the small intestine
- 6 meters
- 19.6 feet
what are the 3 parts of the small intestine in order
- duodenum
- jejunum
- ileum
what is chyme mixed with in the small intestine
- pancreatic juices
- bile
define pancreatic juices
- alkaline solution that neutralizes acidity
- contains digestive enzymes that break down starches, disaccharides, proteins, and fats
define bile
- contains bile salts which make lipids accessible to water-soluble enzymes
- produce by liver
- stored and concentrated in the gallbladder
- enters the duodenum through the bile duct
define the ileocecal valve
- separates the ileum of the small intestine from the cecum of the large intestine
what happens to nutrients and undigested food in the small intestine
- nutrients (monosaccharides, amino acids, bile salts, vitamins, etc): absorbed by cells of intestinal lining
- undigested food: sent to the colon from the ileum through the ileocecal valve
how does the size of the large intestine compare to the size of the small intestine
- large intestine shorter in length but larger in diameter
what happens in the large intestine
- reabsorbs water from indigestible food
- processes waste materials
what are the 3 parts of the large intestine
- cecum
- colon
- rectum
define cecum
- joins ileum to colon
- receiving pouch for waste
define colon
- home to intestinal flora: bacteria that aid in digestive processes
define rectum
- stores feces
- propelled using peristaltic movement during elimination through anus
- regulated by 2 sphincters
what are the 4 regions of the colon
- ascending colon
- transverse colon
- descending colon
- sigmoid colon
what is the purpose of accessory organs in the digestive system
- add secretions and enzymes that break down food into nutrients
- liver, gallbladder, pancreas
define liver
- produces bile which breaks down fats
- processes absorbed vitamins and fatty acids
define gallbladder
- small organ that stores bile
define pancreas
- produces enzymes for digestion of protein and carbohydrates
- secretes bicarbonate buffer that neutralizes acidic chyme
what are digestible and indigestible carbs broken down into
- digestible carbs: glucose
- indigestible carbs: cellulose (dietary fiber)
what are excess sugars converted to and where are they stored
- glucose converted to glycogen
- stored in liver and muscles
what happens if excess sugar reserves are full
- glucose converted to fatty acids
- stored in adipose tissue cell (fat cells)
are proteins obtained directly from food
- no
- must be broken down into amino acids and then used to make protein
how many essential amino acids are there
- 9
why are fats required in a diet
- significant source of energy
- fatty acids needed to make lipid membranes
- aids absorption of fat-soluble vitamins and production of fat-soluble hormones
define essential nutrients
- nutrients that must be eaten because the body cannot produce them
- vitamins, minerals, essential fatty acids, essential amino acids
define vitamins
- organic molecules required in small quantities
- many assist with enzyme function (called coenzymes)
define minerals
- inorganic nutrients that must be obtained from food
- act as enzyme cofactors
define essential fatty acids
- needed to make some membrane phospholipids
- omega-3 alpha-linolenic acid
- omega-6 linoleic acid
define essential amino acids
- 9 amino acids that the human body cannot synthesize
define circulatory system
- system that circulates nutrients, O2, CO2, and waste through the blood
- regulates blood pressure by heart beating
define respiratory system
- system that obtains O2 for cellular respiration and removes CO2 created by cellular respiration
what occurs during inhalation
- diaphragm descends creating negative pressure on the lungs
- lungs inflate as you draw in air through your nasal cavity
how is the air you inhaled prepared before it enters your lungs
- warmed and humidified by mucous membranes
- hair, mucus, and cilia in the nasal passages remove particulates from the air
describe the passage of air through the respiratory system
- nasal cavity
- pharynx
- larynx
- trachea
- bronchi
- bronchioles
- alveoli duct
- alveolar sac
- alveoli
define trachea
- cylinder about 10 to 12 inches long
- rings of muscle and cartilage for structural support
- lined with mucus secreting ciliated cells to filter particles
- connects the pharynx to the lungs
how many bronchi are divided from the trachea
- two primary bronchi
- going into the right and left lung
define bronchioles
- less than 1mm (0.03 inches)
- split from bronchi and spread through the lung
- final bronchioles called respiratory bronchioles
what is attached to each respiratory bronchiole
- alveoli duct containing alveoli sacs
- alveoli sacs containing 20 to 30 individual alveoli
where does gas exchange occur
- alveoli
- thin-walled structures that have direct contact with capillaries
- allows diffusion of O2 and CO2
what is the estimated surface area of alveoli
- 100m^2
- half the area of a tennis court
what is the circulatory system composed of
- network of vessels: arteries, veins, capillaries
- heart
define arteries
- move blood away from the heart
- most move oxygenated blood; exception is pulmonary artery
define veins
- move blood towards the heart
- most carry deoxygenated blood; exception is pulmonary vein
how does blood circulate inside vessels
- unidirectionally (one way)
- from the heart; around one of two paths; back to the heart
- closed system
is the circulatory an open or closed system
- closed system
- invertebrates have open circulatory system
what are the two circuits in the circulatory system
- pulmonary circuit
- systemic circuit
define pulmonary circuit
- blood moving between the heart and lungs
- pumped from right side of the heart
define systemic circuit
- blood moving between the heart and body
- pumped from left side of the heart
describe the heart
- muscle consisting of two pumps (pulmonary and systemic)
- asymmetrical (left side larger)
- divided into 4 chambers
why is the left side of the heart larger than the right
- left side has to pump blood around the whole body, greater distance to cover
define tricuspid valve
- located between the right atrium and ventricle
- prevents backflow from right ventricle to right atrium during systole (contraction)
define mitral/bicuspid valve
- located between the left atrium and ventricle
- prevents backflow from left ventricle to left atrium during systole (contraction)
define pulmonary valve
- located between right ventricle and pulmonary artery
- prevents backflow during diastole (relaxation)
define aortic valve
- located between left ventricle and aorta
- prevents backflow during diastole (relaxation)
what is the function of the right side of the heart
- pumps blood to the lungs so it can be oxygenated
what is the function of the left side of the heart
- pumps oxygenated blood to the body
define cardiac cycle
- flow of blood through the heart coordinated by electrochemical signals that cause the heart muscle to contract and relax
define diastole
- relaxation
- blood flows into the heart while all chambers are relaxed
define systole
- contraction
- chambers push blood through valves
- from atria into ventricles
- from ventricle out of the heart
what are the 3 phases of the cardiac cycle
- cardiac diastole
- atrial systole and ventricular diastole
- atrial diastole and ventricular systole
describe the first phase of the cardiac cycle
- cardiac diastole
- all chambers are relaxed and blood flows into the heart
describe the second phase of the cardiac cycle
- atrial systole and ventricular diastole
- ventricles remain relaxed while atrial systole pushes blood into the ventricles
describe the third phase of the cardiac cycle
- atrial diastole and ventricular systole
- after the atria relax, ventricles contract, pushing blood out of the heart
where does the hearts electrochemical signals start
- sinoatrial (SA) node
- outside of right atrium
- causes atria to contract
where does the hearts electrochemical signal move after the atria contract
- atrioventricular (AV) node
- in right atrium, near ventricles
- causes ventricles to contract
where is blood from the superior vena cava from
- head and upper body
where is blood from the inferior vena cava from
- trunk, lower body, and visceral organs
define aorta
- main artery of systemic circulation
- branches into arteries that take blood to limbs and organs
define capillary beds
- diverged from arterioles
- contain 10s to 100s of capillaries that branch among the cells of the body
define endocrine system
- collection of glands that secrete chemical messages called hormones
- work in coordination with the nervous system to help maintain homeostasis
which two body systems help to maintain homeostasis
- nervous
- endocrine
describe the differences between the nervous and endocrine system
- nervous: uses electrical messages, works quickly, response is short-lived
- endocrine: uses chemical messages, works slowly, response is short or long-lived
define hormones
- chemicals that regulate or control the activity of certain cells or organs
- stimulate a response in cells that have receptors to bind to them (only affect these target cells)
- coordinates many different systems and organs
how do hormones work
- released by cells in one area of the body
- circulate through the body in body fluids (often blood) to target cells
- binds to intracellular hormone receptors
- affects cells in other parts of the body
what are hormones a mechanism of communication for
- between neighboring cells
- between cells and tissues in distant parts of the body
where can hormone receptors be found
- on or in many cells
- may be limited to a small number of specialized cells
do all cells respond to the same hormone; why or why not
- no
- cells have different receptors that bind to different hormones
can cells have many receptors to the same hormone
- yes
can cells have receptors for different types of hormones
- yes
what does the number of receptors on a cell determine
- sensitivity of the cell to that hormone
- can change over time: up regulation and down regulation
define up regulation
- number of receptors increases making the cell more sensitive
define down regulation
- number of receptors decreases reducing cellular response
define pituitary gland
- located at the base of the brain
- does a LOT
define pineal gland
- located behind thalamus in the brain
- “third eye”
- secretes melatonin and helps with circadian rhythm
define thyroid gland
- located in the neck
- stimulates metabolism
- reduces blood calcium levels
define parathyroid gland
- located on the surface of the thyroid
- increases blood calcium levels
define adrenal glands
- located by the kidneys
- stimulates fight or flight response
define pancreas
- located between the stomach and small intestine
- contain exocrine and endocrine cells
define thymus
- located behind the sternum
- contributes to immune system development
define endocrine glands
- release hormones into body fluids (usually blood) that carries them throughout the body
define exocrine glands
- secretes chemicals through ducts that lead outside of the gland (not to the blood)
describe the regulation of hormone production
- concentration of hormones in blood is maintained within a narrow range
- primarily controlled by negative feedback
