IB Biology HL C3

integration of body systems

hierarchy of body systems (5)

cells, tissues, organs, organ systems, organism

cells

specialized according to their shape and organelles

tissues

group of specialized cells that work together

organs

groups of tissue that work interdependently

organ systems

group of organs that work together to fulfill a function

organism

group of organ systems that work interdependently to achieve emergent properties

function of sensory neurons (2)

detect changes and stimuli in internal and external environments

receptors send signals along sensory neuron to CNS

function of motor neurons

sends signal to output, where action happens

two required to reach muscle

motor neurons needed to reach muscle

1. neuron with its dendrites and cell body in gray matter of motor cortex. axon runs out of brain down to spinal cord. terminal in spinal cord.

2. neuron that runs out of spinal cord to desired muscle

nerves (2)

bundle of axon fibres enclosed in protective sheath

generally contains both motor and sensory neurons

reflex

involuntary response to specific stimuli

simplest form of coordination in nervous system (signals on pass through 2-3 nerves)

reflex mechanism (5)

1. stimulus sensed at receptor cell

2. signal passed along sensory neuron

3. signal travels through interneuron to motor neuron

4. motor neuron sends impulse to effector is threshold is reached

5. effecter cells carry out response

cerebellum (2)

provides motor memory (muscle memory) for procedural activities

coordinates precise movements

circadian rhythms (3)

sleep cycle that adapted to 24-hour cycle or depends on exposure to continuous light or dark

when wavelengths of 460-480 nm detected, melatonin production increases

regulated by secretion of melatonin

melatonin (3)

hormone secreted by pineal gland (in brain)

high levels cause tiredness and drowsiness

decreases core body temperature and urine production

components of limbic system

hippocampus, amygdala, hypothalamus

epinephrine / adrenaline

hormone secreted by adrenal glands

causes the fight or flight response / prepares body for vigorous activity

binds to adrenergic receptors in target cells (plasma membrane)

functions of epinephrine / adrenaline

stimulates breakdown of glycogen into glucose

lungs stimulated to increase ventilation rate

sinoatrial node stimulated to increase heart rate

hypothalamus

controls endocrine system with pituitary gland

has neurons that run down into the posterior pituitary

releases hormones into blood stream

sinoatrial node

pacemaker for the heart based on signals from medulla oblongata

receives signals from vagus nerve and cardiac nerve

has receptors for epinephrine to increase heart rate based on distress signals

vagus nerve

stimulates SA node to decrease heart rate

cardiac nerve

stimulates SA node to increase heart rate

medulla oblongata

cardiac centre

receives blood pressure input from baroreceptors (pressure) in walls of aorta and arteries

receives pH and oxygen concentration input from chemoreceptors in aorta and arteries

ventilation rate (2)

number of times air is inhaled and exhaled per minute

regulated by medulla oblongata

ventilation rate feedback control

pH/oxygen change increase at chemoreceptors → impulse sent along cardiac neuron to heart → heart rate increase → ventilation increases → pH decreases

negative feedback loop

positive tropism

growth towards stimulus

ex. root growth

negative tropism

growth away from stimulus

ex. shoot growth

phototropism

change in direction of shoot tip toward bright light

differential growth

different parts of plants growing at different times

the need for light, interact with pigments and hormones

phytohormones

chemical signals released in part of plants to initiate a signal to another part of plant

function of phytohormones

inhibit or promote growth

development like cell specialization

response to stimuli (tropism)

symplast

water and solutes inside of cell

apoplast

the water and solutes in between plant cells in the matrix of cells

microfibrils

inelastic bundles of cellulose fibres that provides rigidity to cell walls

cell walls

needs to be rigid to maintain high turgor pressure

prevent sliding of microfibrils using pectin as crosslinks

auxin (3)

made in apical meristem cells

unable to cross plasma membrane by simple diffusion

causes transcription of genes for protein pumps to move H+

auxin mechanism

pumps protons into apoplast

results in low pH here that removes crosslinks on cell wall

allows cellulose microfibrils to slide and elongate cell

generally elongation happens on shaded side

auxin efflux carriers

type of active transport pump that moves auxin out of plant cells

auxin efflux carriers mechanism

some auxin purposely move into apoplast to insert auxin efflux carrier

since exterior cell is slight acidic, auxin is uncharged and diffuse into adjacent cell and build high concentration

auxin moves cell by cell by entering through simple diffusing and exiting through auxin efflux carriers which are arranged in response to light

functions of the brain

receives signals

cognition

sends signals

central nervous system

made up of brain and spinal cord

processes both conscious and unconscious signals

spinal cord

origin of spinal nerves

contains myelinated axons

information for spinal reflexes

white matter

communication network

sends signals from to and from brain (action)

gray matter

cell bodies of motor neurons and short interneurons (thinking, feeling, memory)

peristalsis

wave-like contraction of circular muscles that move food and waste

ensures one way movement

unconsciously controlled by esophagus to rectum

enteric nervous system

controls unconscious functions

communicates with central nervous system

pathogens

organism that causes disease

replicate in host and use its nutrients

ex. archaeon, eubacteria, fungi, animals, virus, prions

primary defense mechanisms

skin, mucous

skin as primary defence (4)

physical barrier

contains natural bacteria that inhibits growth of pathogenic microbes

sebum lowers skin pH to prevent bacterial and fungal growth

uses tears or saliva to wash away bacteria

mucous (4)

lines respiratory, urinal, gastrointestinal, and reproductive tracts

secretes glycoprotein solution that contains lysozyme that destroy many bacteria

trap pathogens

blood clotting / thrombosis

initiated after puncture in blood vessel

1. release of clotting factors from damaged platelets

2. clotting factors convert thrombin into prothrombin

3. thrombin converts fibrinogen in fibrin

4. fibrin traps blood cells and seals wound

5. scab forms where clot is exposed to air

phagocytes

type of white blood cell

involved in phagocytosis

phagocytosis

1. phagocyte engulfs pathogen

2. ignests and holds whatever it digested in cell

3. presents non-self particles

4. if deemed dangerous, immune response is initiated

stages of antigen production

1. antigen presented by MHC on macrophage

2. helper T cells activate and recognize antigen presented

3. activation of B cells

4. production of plasma cells

5. production of memory cells

6. antibody aided destruction of pathogens

innate immunity

protect from any pathogen

adaptive immunity

targets specific pathogens

clonal selection of B cells

occurs when B cells encounter antigen

B cells divide by mitosis and specialize into plasma cells or memory cells

plasma B cells

secretes specific antibody and activates helper T cell

large amounts of rough endoplasmic reticulum to make lots of antibodies

memory B cells (3)

retained in lymph nodes

if second infection occurs, memory cells respond more rapidly and vigorously

live up to 20 years

primary immune response (2)

first exposure to antigen

takes about 2 weeks to produce maximum number of antibodies

secondary immune response (3)

second exposure to antigen

production of antibodies only takes 2-7 days

memory cells respond more rapidly and vigorously

vaccines

modified forms of pathogen that stimulate body to develop immunity to it without fully developing disease

develops immunological memory (B cells)

causes primary response, so exposure to real pathogen is efficient secondary response

herd immunity

(1 - 1/R) * 100

prevention of epidemics

when significant portion of population has vaccine so pathogen spreads at a very slow rate

HIV (3)

human immunodeficiency virus

retrovirus, uses reverse transcriptase to integrate its RNA into host DNA

uses helper T cells as host, which weakens immune system

HIV transmission methods (3)

breast feeding

transfer of body fluids

cuts/tears in vagina, penis, mouth during sexual intercourse

antibiotics

molecules produced by bacteria and fungi that inhibit vital processes in bacterial cells (competition for resources)

leaves eukaryotic cells unharmed

eg. penicillin

virus and antibiotics

virus’ are unaffected

they are non-living and depend on living cells for metabolism

antibiotic resistance (2)

when bacteria evolve to survive antibiotics

naturally selected (mutation in their gene sequence)

no new antibiotics since 1980s

how to limit antibiotic resistance (3)

limit prescribing antibiotics

farmers avoid feeding their livestock antibiotics

patients completing courses of antibiotics to completely eliminate infection

zoonotic pathogens

infects various species

results from high contact between humans and animals

eg. SARS

macrophages

engulf pathogens and presents pieces

lymphocytes

produced initially by blood stem cells in bone marrow

T cells (helper and killer)

B cells (plasma and memory)

MHC (major histocompatability complex) (3)

embedded in plasma membranes on every nucleated cell

holds piece of whatever has been engulfed by phagocytosis inside cell. presents on outside of cell

non-self pieces (antigens) results in production of antibodies