human body pt 1 Flashcards
levels of organization
cells (smallest unit of life) –> tissues (group of cells of the same type working together) –> organ (two or more tissues working together) –> organ system (two or more organs working together) –> organism
emergent properties
- when individual components with their own unique features work together
- cannot exist without the coordinated effort of subsystems and smaller components
- ex: a leaf and the ability to photosynthesize
- cells (guard cells, companion cells) –> tissues (phloem and xylem, spongy layer, palisade layer), –> ogan (leaf) –> emergent properties (performs photosynthesis, transpires water, protects against UV light)
- can’t be predicted just by studying the individual components alone
organ systems
are integrated and coordinated by the nervous and endocrine systems
endocrine gland
- can also be called the adrenal gland
- produce and release hormones directly into the bloodstream, which have effects WITHIN the body
- hormones act as chemical messengers
- these hormones may be primarily used for local target tissues, depending on the situation, but more often the hormones are carried by the bloodstream to have effects on distant tissues and organs
- sometimes, the response of the tissues or organs continues even after the production of hormones has stopped
all hormones are
molecules (proteins, amino acids, steroids)
nervous system
-uses neutral impulses as the signal
- the nervous system typically targets a single tissue or organ
- the response and end of response is short-lived
hormones vs nerve impulses
hormones work more slowly than nerve impulses but have longer lasting effects on body
endocrine system analogy
endocrine system = postal system, glands are like post offices (hormone producers), hormones = letters (messages), bloodstream = delivery network, target cells = recipients with specific addresses
endocrine vs exocrine
secretion method:
Endo: into bloodstream
Exo: through ducts
transport:
Endo: via bloodstream
Exo: via ducts
target range:
Endo: whole body
Exo: local area
speed of action:
Endp: slower
Exo: faster
duration:
Endo: long-lasting
Exo: short-term
product type:
Endo: hormones
Exo: enzymes, sweat, mucus
hypothalamus and pituitary gland
located: in the base of the brain, pituitary gland is below the hypothalamus
what type of gland: both are endocrine glands
connected to each other by: a stalk
- the glands have blood vessels and neurons integrated into their tissues which allows them to link the cardiovascular and nervous systems together
involved in regulating: circadian rhythm
circadian rhythm
internal clock that keeps the body synchronized with the 24-hour day-night cycle
melatonin production to maintain circadian rhythm
- darkness stimulates production of melatonin by the pineal gland
- lowering body temp, metabolism, blood pressure & sugar
- daylight (specifically blue light) stimulates the retina to send a neutral impulse to the SCN of the hypothalamus then to the pineal gland which suppresses melatonin production
- suppression of melatonin in the morning and through the day prepares and maintains body for activity by raising body temp, blood pressure and sugar, and metabolism
- alternation of melatonin production and suppression establishes sleep-wake cycle
exocrine gland
- produces a substance (not a hormone) that exits the body through a duct
- pancreas is both endo and exo
- produces sweat, tears, milk
epiphrine production for short-term stress response (fight or flight)
- short term tress (startled, scared)
- when a person experiences short term stress, the hypothalamus sends nerve impulse to spinal chord which in turn sends a new nerve impulse to the adrenal glands (located at the top of the kidneys)
- the adrenal glands respond by producing the hormone epinephrine or adrenaline
- adrenaline goes into the bloodstream
- epinephrine has many effects together sometimes called fight or flight response
- fight or flight response: breathing and heart rate increases, blood pressure rises, pupils dilate
- liver is stimulated to break down glycogen into glucose, increasing blood sugar levels
homeostasis
- a term for the coordinated efforts of an organism’s levels of structure to maintain a steady state
- all living organisms (including single celled organisms) carry out homeostasis
- in a homeostasis system there’s a set point
- if there’s a deviation from set point, the system detects the change and instigates a response to bring conditions back to the set point
- this is called a negative feedback loop
thermoregulation
- a negative feedback loop
- process by which body maintains its core temp within a narrow range, which is 37 degrees celcus or 98.6 F regardless of environmental temp changes
- essential for enzyme function and overall survival
- organ responsible for detecting body temp is the hypothalamus
- if body temp goes above 37, the hypothalamus releases signals for the blood vessels to dilate and skin to sweat
- hypothalamus also inhibits the production of thyroxine hormone from the thyroid
- less thyroxine slows down the metabolism rate and thus produces less heat
- if temp is below 37, the hypothalamus signals the blood vessels to constrict, muscles to shiver and arrector pili muscles connected to hair follicles to raise hairs (goose bumps)
vasodilation
- when blood vessels dilate (widen)
- in thermoregulation, the blood vessels in the skin vasodilate to bring blood to the surface where sweating and evaporative cooling will help lower body temp
- this is why a persons face will be flushed red when overheated
- vasoconstriction: the opposite of vasodilation
- its done to move blood away from this surface and towards the body core to conserve heat
- this is why a persons face is pale when cold
- thyroxine is stimulated by the hypothalamus to be produced by the thyroid gland when a person is cold
blood sugar
- is also homeostatically controlled by a negative feedback loop and has a set point
- set point: 70mg/100ml for teenagers and 100mg/100ml for adults > 45 yrs
- if blood sugar rises above set point after eating meal or beverage, the pancreas will be stimulated to release insulin from the beta cells of the pancreas
- insulin is a hormone that causes the liver and muscles to uptake glucose from the blood and convert into glycogen which lowers blood sugar levels
- if blood sugar levels fall below set point the alpha cells of the pancreas are stimulated to release glucagon. this hormone causes the liver to break down glycogen into glucose which raises blood sugar levels
diabetes
- full name is diabetes mellitus (DM)
- two types: T1DM, T2DM
T1DM: - person’s body isnt producing enough of the insulin hormone
- as a result glucose lingers in the bloodstream, causing elevated sugar concentration (hyperglycemia)
- these people must monitor blood sugar after meals and inject insulin as needed
- T1DM usually manifests itself during childhood or early adulthood
- has strong genetic factors
T2DM: - person’s body IS producing insulin, however the body’s cells have become resistant to the hormone
- hyperglycemia still ensures but for diff reasons
- do not have to inject insulin but may take medication to increase sensitivity of cells to the hormone
- T2DM usually manifests itself later on in life, and is strongly correlated with:
- inactivity, obesity, smoking, large intakes of sugars
- average age of onset is getting younger due to the childhood obsesity global pandemic and poor diet
excretion
- the removal of water and waste from the body through the urinary system
- the primary organs of the excretory system are the kidneys
- blood flows to kidneys and organs filter out excess water, salt & metabolic wastes (such as urea)
- urea forms urine which is stored in the bladder until emptied via the urethra
- kidneys are not just responsible for filtering blood to form urine but also for osmoregulation
what is osmoregulation
- adjusting solute concentration to maintain a steady state of about 300 mOsm/L.
- solute conc is milliOsmos (mOsm/L)
- a customary unit for all human fluids
what is osmolarity
- a measure of all solute concentrations together per unit volume
how many nephrons in a kidney
- around 1 million
the nephron is
- a structure that filters blood to remove water, salts and metabolic wastes
blood is delivered to the nephron by
- arterioles to the cup-like structure called the Bowman’s capsule
Inside the bowmans capsule
- the arterioles branches to form a capillary bed called the glomerulus
the diameter of the
- afferent arteriole is larger than the efferent arteriole
- this creates higher blood pressure in the capsule
fenestrae
- blood plasma leaks from the glomerulus into the capsule through tiny pores in the blood vessel walls called fenestrae
what can and can’t pass through the fenestrae
CAN
- small molecules (glucose), water, salt, other ions, metabolic waste (urea)
CAN’T
- cells, large molecules (such as antibodies, albumin proteins, blood clotting factors)
the fluid also goes through
- a basement of membrane between the capillary and the capsule made of glycoproteins in a mesh
filtrate
- finally the fluid passes through pedicels of podocytes that wrap around the capillaries into the Bowman’s capsule where it’s now called filtrate
ultrafiltration
- the combination of high blood pressure wth the structures of the capillary to force out plasma fluid
how many times the kidneys filter the body’s blood through the day
around 50 times a day
