IB Biology HL: Biological Coordination and Communication (2)

B3.1 Muscle and Motility (HL); D3.3 Homeostasis; C3.1 Integration of Body Systems

nervous system

receives sensory info through structures called receptors and send motor responses to muscles, resulting in movement (only for animals)

epinephrine (adrenaline)

the hormone adrenal glands secrete when facing stressful situations

fight-or-flight response

allows body to react to a potentially life-threatening situation

endocrine system

consists of glands that respond to chemical signals in the body with the production/release of hormones (only affect activity of specific target cells); present in both animals and plants

hypothalamus

area of the brain that acts as a link between the nervous/endocrine system

glandular cells

produce different hormones that either stimulate hormone release by pituitary gland, or inhibit this release

adenohypophysis (anterior pituitary)

glandular front of the lobe of the pituitary gland located at the base of the brain, produces and secretes most of the hormones (ex: FSH, LH)

neurohypophysis (posterior pituitary)

posterior lobe of the pituitary gland, which stores and releases oxytocin and ADH produced in the hypothalamus

sinoatrial (SA) node

the natural pacemaker of the heart

baroreceptors

receptors that detect changes in pressure, located on the arch of the aorta and 2 carotid sinuses

stroke volume

volume of blood pumped out of the heart

chemoreceptors

monitor blood content in capillaries, their cells can release a neurotransmitter that initiates action potentials carried to the medulla oblongata; many located in the tongue for tasting

photoreceptors

located within the retina of the eyes for visual information

thermoreceptors

located in the skin to provide information on temperature changes

mechanoreceptors

specialized sensory receptors that respond to mechanical force such as touch, pressure, vibration, stretch, sound

osmoreceptors

in carotid arteries and hypothalamus of the brain, which sense solutes and the water content of blood

proprioreceptors

in muscles and joints, provide the brain with sense of balance and coordination, especially when the body is moving

spinal nerves

impulses sent in and out of the spinal cord by these 31 paired nerves, which emerge directly from the spinal cord

cranial nerves

the brain’s set of 12 paired nerves that connects various parts of the body to the brain through the brainstem

cerebrum

divided into right and left cerebral hemispheres, and each consists of 4 lobes (frontal, temporal, parietal, occipital) that dominate conscious activities

cerebellum

coordinates voluntary movements, controls balance/equilibrium

brainstem

relays impulses between the cerebrum, cerebellum, and spinal cord; also responsible for most functions associated with the autonomic nervous system; all functions occur at a subconscious level

medulla oblongata

regulates both breathing, blood pressure and heart rate

central nervous system (CNS)

brain and spinal cord

spinal cord

controls some unconscious reflexes associated with balance and other skeletal muscle, functions independently of the brain

enteric nervous system (ENS)

a separate nervous system that keeps food moving along the digestive tract

peristalsis

involuntary, wave-like muscle contractions and relaxations that move food contents through the digestive tracts

peristaltic reflex

series of smooth muscle contractions that occur along the entire length of the alimentary canal and keeps the food moving

bolus

round masses of food formed when it moves through the alimentary canal

excitatory neurotransmitters

released by motor neurons to an area of smooth muscle behind the bolus to stimulate smooth muscle contraction, causing the bolus to be pushed alon

inhibitory neurotransmitters

released by motor neurons ahead of the bolus to relax smooth muscle and create open space ahead for the bolus to slide through

white matter

tissue of the spinal cord that contains axons/neurons to carry impulses to/from the brain

grey matter 

butterfly-shaped tissue of the spinal cord that contains neurons and synapses involved in spinal cord integration processes

reflex arc

the pathway of the impulse where the sensory information enters the grey matter of the spinal cord and motor information is immediately sent back out

receptor

modified neuron capable of transduction

transduction

conversion of a physical stimulus into an electrical signal, called an action potential, that is carried along a neuron

motor neurons

carries action potentials to muscle tissues from the CNS

motor cortex

the portion of the cerebrum that sends the action potentials, located in the most posterior part of the frontal lobe of the cerebrum

motor end plates (neuromuscular junctions)

muscle fibers that motor neurons synapse with

sarcomeres

the release of acetylcholine is a chemical signal that initiates the contraction of this

nerve

collection of neurons surrounded by a protective sheath

phytohormones

plant hormones

phototropism

plants have evolved this mechanism to enable them to have directional growth towards light (for plants, it’s positive since there’s an attraction to the light stimulus)

gibberellin

phytohormone that controls stem elongation, seed germination, flowering, and dormancy

auxin

phytohormone that is produced in the growing parts of the plants, specifically in the tips of the shoots and roots and growth buds; promotes growth by lengthening cells; transported in the phloem sap, since it needs to go to different parts of the plants

auxin efflux carriers

special membrane proteins that allow auxin to move from source to sink

synthesis of proton (hydrogen ion) pumps

promoted by auxin when it enters the cell

apoplast

where fluids is concentrated when proton pumps move hydrogen ions from the cell interior through plasma membrane

expansin

loosens the hydrogen bonds that cross-link cellulose fibers, allowing the fibers to move past each other into new positions

higher internal turgor pressure

created by absorption of water to create the necessary force for the fibers to slide past each other

cytokinin

contributes to the growth of a plant but is produced in the root-growing region and transported in the xylem fluid (because the flow is unidirectional from roots to shoots)

ethylene (ethene)

the gas produced by fruit in the stage of ripening

sensory neurons

neurons that carry action potentials from the receptors to the CNS

interneurons

between the sensory and motor neurons, only found within the CNS

mixed nerves

31 pairs of spinal nerves contain both sensory and motor neurons, carrying action potentials in opposite directions

nocireceptor

pain receptor

circadian rhythm

any pattern of behavior/physiology based on a 24-hours cycle

melatonin

hormone produced by the pineal gland (which controls the circadian rhythm of the wake-sleep cycle); high during the night for diurnal animals, high during the day for nocturnal animals

homeostasis

regulatory mechanisms to keep specific physiological factors within preset limits

negative feedback mechanisms

physiological processes that bring a value back towards a set point

endocrine system

system that consists of multiple glands that produce hormones, which are transported in the bloodstream to reach specific target cells that will produce a response when in contact with the hormones

Islets of Langerhans

pancreatic cells that produce insulin and glucagon, located in the endocrine portion of the pancreas

β (beta) cells

cells that produce insulin

α (alpha) cells

cells that produce glucagon

diabetes

a disease characterized by hyperglycemia

type 1 diabetes

autoimmune disease where the immune system mistakenly destroys the beta-cells of the pancreas (insulin can’t be produced); usually has an early onset (children), but can affect people of any age

type 2 diabetes

a result of body cell receptors that don’t respond properly to insulin, and the cells do not take in sufficient glucose

ectothermic

animals whose internal temperature is equal to that of their environment

endothermic

organisms that maintain a body temperature warmer than the external environment itself most of the time, requiring extra nutrition just to generate internal body heat

receptor (element of a feedback mechanism)

detect changes

control center

processes the information in order to elaborate a response

effector

carries out the response

thermoregulation

process of maintaining the internal body temperature within a stable range

perspiration

process in which sweat evaporates from the skin to provide evaporative cooling, since heat is transferred to the water in the sweat

vasoconstriction

the constriction of blood vessels when the body temperature falls below 37ºC to allow more warm blood to be sent to vital organs

goosebumps

raised hairs on the skin as a result of the release of epinephrine in cold environment

thyroxine

a hormone released by the thyroid gland (which is stimulated by the pituitary gland) to increase the metabolic rate of all body cells and generate heat

shivering

an autonomic response to the cold that’s initiated by the hypothalamus to allow muscles to generate body heat

blubber

the adipose tissue that helps retain warmth that some animals (especially marine mammals) have evolved to use

brown adipose tissue

contains more mitochondria compared to other fat cells; when needed, the mitochondria begin cell respiration, which is uncoupled from ATP production (therefore, glucose is oxidized just to generate body heat)

capillary beds

networks of microscopic blood vessels that connect arterioles to venules, enabling the exchange of gases, nutrients, and waste products between the blood and body tissues

osmoregulation

regulation of the water content in the blood; the water content in the urine is altered based on the water intake, perspiration levels, and other factors; the process in which the loop of Henle establishes a salt gradient, which draws water out of the collecting duct

excretion (kidney)

the process of filtering waste, excess salts, and water from the blood to produce urine

nephron

the basic functional unit of the kidney (1 million in each), has a long tube which starts at the Bowman’s capsure and ends at the collecting duct (drains into the renal pelvis), consists of: a glomerulus, the Bowman’s capsule, the proximal convoluted tubule, the loop of Henle, and the distal convoluted tubule

peritubular capillary bed

a secondary capillary bed that surrounds the three-part tubule

collecting duct

part of the kidney that collects urine (shared by multiple nephrons); fluids enter here from the distal convoluted tubule; here, the process of osmoregulation will continue through the absorption of water; permeable to water (permeability depends on the amount of ADH released by the pituitary gland); target tissue of ADH; liquid surrounding it has high osmotic concentration, making the process of osmosis easier once aquaporins are present

glomerulus

a capillary bed that filters various substances from the blood

Bowman’s capsule

a capsule surrounding the glomerulus

filtrate

the fluid initially filtered out of the blood by the glomerulus

ultrafiltration

blood is filtered out of the glomerulus at the Bowman’s capsule to form a filtrate

selective reabsorption

usable materials being reabsorped in convoluted tubules (both proximal and distal)

afferent arterioles

very small branches of the renal artery that bring unfiltered blood to the nephron branches; branch into the glomerulus once inside the Bowman’s capsule

renal artery

brings oxygenated blood from the heart to the kidneys to filter waste and excess water

fenestrations

located between the cells in the wall of the capillaries, they are small openings on the walls of the glomerulus that open under high blood pressure caused by the small diameter of the efferent arteriole when blood is drained through them; they allow fluid to escape, but not cells

efferent arterioles

blood vessel that carries blood away from the glomerulus after filtration has occurred; it’s a small vessel with a narrower diameter than the afferent arteriole to maintain high pressure in the glomerulus to facilitate filtration and is crucial for regulating the kidney’s filtration rate; portions of the blood that weren’t filtered (including cells and proteins) exit the Bowman’s capsule in the efferent arterile

basement membrane

made up of negatively-charged glycoproteins that prevent plasma proteins from being filtered out

podocytes

extensions that wrap around the glomerulus and many short side brances (pedicels), they act as a barrier (large molecules and cells cannot leave the blood)

proximal convoluted tubule

where the filtrate from the glomerulus enters; substances reabsorbed here will be taken back to the bloodstream via the peritubular capillary bed; its wall is only 1 cell thick (single ring), and its inner portion has microvilli (microscopic projections towards the lumen of the tubule) that increase the surface area for reabsorptions

urea

the main waste product present in the filtrate; it’s a result of protein metabolism; it’s the molecule that have to make a compromise between toxicity and the need for temporary storage until it is excreted (produced by mammals, many amphibians, and sharks among other organisms)

ammonia

common waste product resulting from the excretion of toxic products by different organisms (as a result of the metabolism of proteins); requires the least energy to produce (most toxic compound), so it must be expelled continuously (example: aquatic organisms, like most bony fish)