IB HL BIO YR 2 UNIT THREE-A

Hierarchy of organization

cells, tissues, organs, organ/body systems, organism

Emergent properties

properties that arise due to the integration of subsystems

cannot usually be predicted based solely on the understanding of each individual component

Tissue

group of cells that are similar in structure and function as a unit

Nervous system

composed of brain, spinal cord, and nerves

coordinates and controls functioning of other systems by sending nerve impulses through neurons

act quickly but last for a short time

help integrate body systems

Central nervous system (CNS)

brain and the spinal cord

Peripheral nervous system (PNS)

nerves that connect brain/spinal cord to the rest of the body

also contains somatic and autonomic nervous systems

Somatic nervous system

regulates voluntary movements

Endocrine system

network of glands that secrete chemical messages (hormones) into blood for transport to target organs

act slowly but last longer

Cerebrum

largest part of the brain

controls vision, hearing, touch, taste, speech, thinking, movement

split up into four lobes

Cerebellum

plays an important role in voluntary muscular movements, balance and coordination

Memory

the storage and recall of learning

can be explicit or implicit

Explicit/Declarative memories

things that we intentionally try to remember

Implicit memories

memories that help us carry out day to day tasks

things we can do without even thinking about it

Plasticity

ability of neurons to grow and reorganize themselves

Chemoreceptors

specialized receptors that detect changes in pH

in the medulla

Enteric nervous system

part of the autonomic nervous system

extends from esophagus to rectum

controls and coordinates all parts of digestion except swallowing and egestion of feces

Homeostasis

process by which organisms maintain a relatively stable internal environment to combat external changes

regulates body temperature, blood pH, blood glucose levels, blood osmotic concentration

Positive feedback loop

a system responds to changes in its environment by amplifying the direction of the change

ex- oxytocin → contractions → more oxytocin → even stronger contractions

Negative feedback loop

a system responds to changes in its environment by reversing the direction of the change

returns homeostatic variables to a set point

ex- cold temperature → shiver to produce heat, exercise → sweat

hormones

chemical messengers produced by endocrine glands

released into bloodstream and travel to target areas

travel long distances and can act on many cells

ex- epinephrine, insulin, oestradiol, progesteron, testosterone

neurotransmitters

chemical messengers produced by neurons

released into synapses

only act locally

can be composed of amino acids, peptides, amines, or nitrous oxides

ex: acetylcholine

cheetahs (case study)

emergent properties allow them to be good predators

muscular & skeletal systems → high speeds

nervous system → respond quickly

sensory organs → heightened smell and hearing

protein receptors

play a key role in cell to cell communication

have binding sites with specific shapes/chemistry that allows for specific signals to bind

ligand

signaling chemicals that bind to protein receptors

cause a change in metabolism

quorum sensing

form of cell to cell communication in bacteria

allows bacteria to regulate behavior according to population density

leads to a common response from all cells

autoinducers

chemical messengers that allow bacterial cell to cell communication

increase concentration as population increases

once it reaches a critical concentration → binds to specific receptors that trigger a cascade of metabolic reactions

vibrio fischeri (case study)

use quorum sensing to express genes for bioluminescence

high autoinducer concentration binds to LuXR receptor proteins, activates genes for bioluminescence, enzyme luciferase is made → light is emitted

amine hormones

derived from amino acids

amino acid is modified and carboxyl group is removed

ex- epinephrine

protein hormones

large polypeptides that act as chemical messengers

ex: insulin, FSH, LH

steriod hormones

steriods that act as chemical messengers

ex- ibrio fischeri

cytokines

chemical messengers involved in immune response through cell to cell communication within immune system

regulate development, activation, and behavior of immune system cells

calcium ions

act as secondary messengers within cells in a variety of processes

can be stored intracellularly or can enter cells through gated ion channels in response to stimuli

help muscle contractions

transmembrane receptor proteins

integral proteins that span entire bilayer

aid signalling chemicals (ex-ligands) to pass through membranes

intracellular receptor protein

in nucleus and cytoplasm

signalling chemicals diffuse through membrane and then bind to theseproteins to initiate cellular responses.

acetylcholine receptors

transmembrane proteins in axon presynaptic membrane

receive acetylcholine from postsynaptic neuron

when acetylcholine attaches → sodium channel is opened

g proteins

found in cytoplasm

made of three subunits (alpha, beta, gamma)

when inactive, GTP is attached to alpha subunit

when a ligand binds, shape changes, GDP is released and replaced by GTP, alpha subunit detaches

epinephrine

peptide hormone

cant pass through a membrane

binds to GPCR protein and activates it → alpha subunit detaches and converts ATP to cAMP

cyclic AMP (cAMP)

secondary messenger

triggers cascade of reactions that result in a change in metabolism

tyrosine kinase receptors

transmembrane receptors

activate kinase enzymes

have an extracellular ligand binding site and an intracellular tyrosine kinase domain that catalyzes the phosphorylation of itself

insulin binds to this

testosterone

steroid hormone

can diffuse through a membrane

binds to specific proteins in cytoplasm/nucleus to form an active hormone-receptor complex to promote gene transcription

involved in male reproductive system

oestradiol

steroid/estrogen hormone created by ovaries

binds to receptors in cytoplasm of hypothalamus cells → GnRH is secreted → development of follicles during menstrual cycle

progesterone

steroid hormone produced in ovaries

levels of this increase post-ovulation

binds to protein receptors in the endometrium

stimulates the thickening of endometrium in preparation for an embryo

plasma (blood)

plays an important role in integrating organs and organ systems because it transports materials between different parts of the body

transports the following

• oxygen (lungs → respiring tissue, using RBCs)

• carbon dioxide (respiring tissue → lungs)

• hormones (endocrine glands → target cells)

• nutrients (digestive system → liver or other organs for assimilation)

• antibodies (produced by WBCs → sites of infection)

• urea (liver → kidneys → excretion)

55% of blood

cerebrum

outer layer of brain

learning, memory, language, consciousness

cerebellum

little brain at the back

balance and muscle coordination

processes information about current position and movement

medulla

part of brain that controls unconscious/involuntary activities (breathing, heartbeat, etc)

hypothalamus/pituitary gland

control endocrine system

thermoregulation

controls homeostasis through hormones

spinal cord

pathway for communication between brain and body

pain reflexes

conscious processes

mental activities that an individual is aware of (learning, decision making, etc)

unconscious processes

things that happen without conscious awareness (digestion, heartbeat, etc)

nerves

bundles of sensory and motor neurons

surrounded by protective sheath

can be myelinated or unmyelinated

sensory neurons

convey messages from sensory receptors to spinal cord to brain

motor neurons

convey messages from the brain to the spinal cord to the effectors (muscles, etc)

can stimulate muscles to contract (movement)

pain reflex arc (when touching hot things)

pain receptors in skin respond to high temperatures

stimulates action potential in sensory neurons → stimulate action potential in interneurons (spinal cord) → stimulate action potential in motor neurons → muscles contract

does not involve brain, doesn’t go past spinal cord

quick and efficient to keep us safe

anterior pituitary gland

hypothalamus secretes releasing factors which cause _____ to make specific hormones

posterior pituitary gland

stores hormones from hypothalamus

cant make hormones

circadean rhythms

physical, mental, and behavioral changes on a 24 hour cycle

mostly respond to light and dark (melatonin)

baroreceptor

stretch sensitive receptors that monitor blood pressure

monitor how wide arteries are

send signals to medulla

chemoreceptors

detect changes in blood chemistry (O2/CO2 concentration, pH, etc)

send signals to medulla

autonomic nervous system

system that controls bodily function not under conscious control

peristalsis

involuntary relaxation and contraction of muscles to move contents along digestive system

fasting blood glucose levels

normally between 3.9 and 5.6 mmol/L

high blood glucose levels

detected by pancrease

beta cells in pancrease secrete insulin into bloodstream

insulin travels to target cells (mainly in liver/muscles)

binds to insulin receptors in surface that signals for the cells to take in glucose from bloodstream

liver cells

convert glucose to glycogen for storage

muscle cells

use more glucose for aerobic respiration than other cells

low blood glucose levels

alpha cells in pancreas secrete glucagon into bloodstream

glucagon travels to liver and binds to glucagon receptors

triggers cells to convert glycogen to glucose to be released into bloodstream

type one diabetes

autoimmune disease, typically starts in childhood, is genetic, cant prevent it

beta cells are damaged and cant produce insulin

can be helped by injecting insulin, monitoring blood glucose levels, healthy diet, and exercise

type two diabetes

may be genetic but can be prevented/controlled by diet and exercise, associated with excess body weight and lack of exercise

beta cells produce insulin but liver/muscle cells don’t respond/are resistant to it

thermoregulation

the process by which we regulate our internal temperature

done by hypothalamus

negative feedback loop

peripheral thermoreceptors

monitor body temperature

when detect a change in temp → send nerve signals to hypothalamus

endotherm

type of animal

use physiological means of regulating body temperature

generate internal heat

ex: mammals, birds, etc

vasoconstriction

happens when we’re cold

narrowing blood vessels

less blood flowing so blood/heat stays in your core

less heat loss through skin

vasodialation

happens when we’re hot

widening of blood vessels

more blood flowing away from core so heat can escape through skin

shivering

caused by rapid contraction and relaxation of skeletal muscles when were cold

requires ATP from cell respiration to contract muscles → another byproduct is heat

sweating

release of water from sweat glands

water evaporates by absorbing heat energy from skin

hair erection

muscles in skin contract (goose bumps) to pull hair shafts upright

traps air/acts as insulator

limited impact in humans because we don’t have much hair

brown adipose tissue (BAT)

type of fat that contains high concentration of mitochondria

does uncoupled respiration that produces heat but not ATP

excretion

removal of metabolic waste from body in the form of urea

osmoregulation

maintenance of internal balance between water and dissolved materials by an animal regardless of environmental conditions

nephron

functional unit of kidney

used to filter blood and produce urine

millions of them in each kidney

ultrafiltration

occurs in glomerulus

produces a filtrate (water, amino acids, glucose, urea, ions, creatine, etc) that enters the bowman’s capsule

glomerulus

cluster of capillaries in bowman’s capsule

ultrafiltration occurs here (but blood and protein arent filtered here unless there is a malfunction)

proximal convoluted tube

useful substances from glomerular filtrate need to be reabsorbed into body

actively transport glucose and amino acids (needs ATP and mitochondria)

water leaves by osmosis

one cell thick → rapid transport

folded and microvilli to increase surface area and therefore increase reabsorption

descending loop of henle

permeable to water

water leaves the nephron here using aquaporins

ascending loop of henle

actively transports sodium into kidney medulla to make it salty and increase water absorption in the descending loop of henle

not permeable to water

distal convoluted tube

diluted urine enters from the loop of henle

balances blood pH and mineral concentration

urine leaves here and goes to collecting duct

osmoreceptors

in hypothalamus

monitor osmotic concentration of blood

antidiuretic hormone (ADH)

released by pituitary gland when blood concentration is too high

negative feedback loop

reproductive system functions

produce sex cells (eggs and sperm)

transport sex cells within reproductive tracts

produce offspring (fertilization)

nurture developing offspring (females only)

produce hormones that aid in regulating these functions

male reproductive structures

testes

epididymus

vas deferens

prostate gland

penis

testes

glands where sperm and testosterone are produced

held in scrotum (outside the body to keep cool)

seminiferous tubes

network of coiled tubes in each testis

sperm are produced here using meiosis

spermatogenesis

sperm maturation

takes roughly 70 days

epididymus

coiled tubes in scrotum where sperm complete their development

vas deferens

tube that transports sperm from epididymis to ejaculatory ducts and urethra

male urethra

used to discharge urine and semen from the body

prostate gland

produces a thin, alkaline fluid that helps sperm move

fluid is secreted into vas deferens and mixed with sperm

located below bladder

bulbourethral glands

two small glands located beneath prostate

secrete a fluid that helps sperm survive vagina’s acidic environment

seminal vesicles

pair of glands under the bladder

produces a thick fluid made up of fructose (energy for sperm to survive)

semen

sperm plus the fluids from prostate gland, bulbourethral gland, and seminal vesicles combined