Bio unit 3: intergration of body systems

https://docs.google.com/presentation/d/17jhC3hq8t35ZbFEb4n_3dwULh2e5HYY_g31guy40P1Q/edit#slide=id.g2ae189293de_0_207

nervous system (slide 5, 10, 14)

overview:

stimuli (environment) received by receptors → activates action potential in sensory neurons → relay neurons pass on information to spinal cord and brain → motor neurons bring signals from CNS (brain and spinal cord) to effectors →projects axon (indirectly or directly) to control effectors (glands or muscles)

Characteristics:

composed of many neurons

• interact together sending messages throughout the entire body

made of 2 systems

• central nervous system

• peripheral nervous system

system is interdependent with endocrine system

Endocrine system

composed of glands (a system of glands)

they secrete (Release) (into the blood stream(transport system)), produce, and store hormones (chemical signals)

glands are not connected (do not need to know all the glands)

controlled by the hypothalamus of the brain (CNS)

via a neural and hormonal connection to the pituitary gland (the master gland, secretes hormones, controls other glands)

withdrawal reflex (pain reflex arc) (slide 9)

automatic response enacted to withdraw a limb from a painful stimulus (involuntary)

free nerve ending sensory neurons are activated from sensory input from environment

input is detected via receptors (nocireceptor) → initiates a nerve impulse (activation, action potential)

interneurons then relay (relay neuron) the action potential from sensory neuron to the motor neuron

motor neuron (cell body in the CNS (central nervous system) axon projects directly or indirectly to control effector (gland or muscle)))

other characteristics:

intensity of reflex is proportional to the intensity of the pain

polysynaptic reflex

synapses are located in the grey matter of the spinal cord

sensory receptors (slide 11)

any type of cell that can detect numerous types of stimuli (sound, touch, taste)

main function is to send signals via sensory neurons to the CNS (central nervous system)

the brain (slide 13, 14)

core structure:

cerebrum

• left cerebral hemi(half)sphere

• right cerebral hemisphere

• makes up most of the brain

Brain stem

• midbrain

• pons

• medulla

Cerebellum

• motor control and coordination

• significant part of the brain

• helps with balance

function:

central coordinator of information

• unconscious and consicous processes

• recieve complex sensory inputs

• learns (formation of new synapses and strengthening synaptic connections)

• form memory (stores learning, stores conscious memory and unconscious memory)

spinal cord (slide 14)

coordinates unconscious responses (e.x. reflexes)

conveys signals to and from the brain

brain and motor control (slide 15)

left and right cerebral hemispheres control muscles via motor neurons

• cause muscles to contract (ex. skeletal muscles, smooth muscles of intestines, blood vessels, irises of the eye)

left controls right side of the body and vice versa

cerebellum (slide 16)

found at the base of the brain

functions: coordination of contraction of skeeltal muscles

overall control of body movement (percision and timing) (e.x. balance, posture, walking, running)

unable to intiate muscle contraction

recieves input from cerebral hempisheres (cerebrum)

involved in motor learning (learning new motions)

Nerves (Slide 17)

bundles of axons of neurons

sensory and motor neurons

myelinated and unmyleniated

nerve fibers are bundled togther inside protective sheaths of connective tissue

feedback loop

a response

in a system, an output is measured to provide input t o the system

negative feedback

if an output increases, the system reacts to decrease it, and vice versa

• negative means in the opposite direction

• used for homeostasis (maintaining conditions within set limits)

ex. if blood oxygen conc. decreases, the brain detects this and reacts by increasing the breathing rate which increases oxygen

positive feedback

increase of an output causes an even greater increase in the output

ex. uterine contractions during birth: contractions cause an increase in contractions

medulla oblongata

• part of brainstem (base of the brain)

• regulates cardiovascular and respiratory systems via nerve impulses

  • increases & decreases heart rate and ventilation rate based on

sensory input from baroreceptors and chemoreceptors

• located in carotid arteries and the aorta

the medulla can increase or decrease:

heart rate

stroke volume

ventilation rate

stroke volume

the volume of blood pumped by the left ventricle in one contraction

ventilation rate

contraction of exterior intercostal (located in ribcagge) muscles and diaphragm for inhalation and interior intercostal muscles and abdominals for exhalation

baroreceptors and chemoreceptors

Chemoreceptors are cells that detect concentrations (sensory input) of O₂, CO₂, and blood pH

• increased cell respiration increases CO₂ conc., and decreases O₂ conc. & pH

• chemoreceptors detect this and send signals to the medulla

• the medulla sends signals to the heart to increase heart rate and to the diaphragm and intercostal muscles to increase ventilation rate

Baroreceptors (aka stretch receptors) are cells that detect the changes in the circumference of arteries (the degree that they are stretched by blood pressure)

• high blood pressure increases circumference/stretch 

• baroreceptors signal the medulla and the medulla decreases heart rate and stroke volume and dilates blood vessels

peristalis

coordinated contraction and relaxation of smooth muscle in the digestive tract that moves materials through the digestive system

swallowing: voluntarily controlled by the CNS (brain + spine)

peristalsis from esophagus to rectum: involuntary control by the ENS

enteric nervous system (ens)

collection of nerves from esophagus top the rectum

• functions independantly fo the CNS

• coordinates movement of material throuhh the gut

egestion of feces: voluntarily controlled by the CNS

hormones (part of the endocrine system)

bind to receptors on target cells/organs

control and coordinate other organs

pituitary gland

• the pituitary gland secretes hormones

• that control other endocrine glands 

• (known as the “master gland”)

Vasopressin (ADH)

hormone (need to know)

Adrenal Gland

renal refers to kidney

the hormone epinephrine/adrenaline is released from adrenal glands

• in response to stress (the trigger) (fight or flight response)

affects various organs

prepares for vigorous activity with intense muscle contractions

increased:

• heart rate

• blood pressure

• ventilation

• blood glucose conc

• fatty acid conc

• blood flow to skeletal muscles

  • dialates blood vessels supplying skeletal muscles

  • constricts other blood vessels

brain and sense organs become more alert

Circadian rhythm

24 hour pattern of physiological changes

mainly affected by light-dark cycle:

light → photoreceptors (detect change in light activity)→ optic nerve → pineal gland → dec. melatonin

dark → photoreceptors → optic nerve (part of nervous system), sends electrical signal → pineal gland (endocrine system) secretes → inc. melatonin (hormone)

also affected by:

food intake, stress, physical acitivty, social environment, temperature

melatonin

hormone

regulate the sleep/wake cycle

diurnal (daily) pattern of melatonin secretion by the pineal gland

induces sleep by dec brain acitivty, temperature, other hormones (ex. cortisol)

during adulthood and adolesence,

systems

human body is collection of systems

system:

• interacting and intedependant parts that create emergent properties

e.g. neuron could not sustain itself or achieve coordination without other cells and systems

interaction and interdependance rquires coordination

• the nervous or endcrine systmes coordinate body systems

cardiovascular system

heart + blood vessels

aids in the interaction and interdepndance between body systems

carries materials and energy (like a highway):

• hormones from glands to targets

• chemical energy in nutrients

• o2

• waste products (e.g. co2)

• distributes heat energy arnd the body

transportation system and heat system

hierarchy of subsystems

• Hierarchy: cells → tissues → organs → body systems → organism

• Each level is a subsystem of the next level.