Year 9 Biology

communication system, controls all parts of your body

made up of brain and spinal cord

receives info from all over body, processes it and sends out msgs that tell body how to respond

made up of nerves that carry out nerve impulses to & from CNS

control centre of body

tells diff parts of body what to do through NS nerve impulses

largest part of brain, made of 4 lobes

higher thought (critical thinking, emotions)

vision (colour, spatial awareness, movement)

processes sensory info (4 other senses, body position)

near rear, lower part of brain

responsible for balance, coordination + fine & gross motor movement

connects brain to spinal cord, located at base of brain

responsible for many involuntary processes (heartbeat, movement of stomach and intestines

top part of brainstem

below midbrain

bottom-most part of brain

directly above brainstem, below thalamus + above pituitary gland

responsible for keeping body in a stable state: homeostasis

parts of CNS that contain neurons covered in myelin

where axons are connecting diff parts of grey matter to eachother

parts w/ mainly cell bodies, dendrites + synaptic terminals

where the “thinking” occurs

carry signals from CNS to effectors

muscle cells/glands

put messages into effect

carry signals from cells in sense organs to CNS

e.g. pain receptors in neck

link sensory neurons directly to motor neurons

only make connections with other neurons

carries signal away from cell body to axon terminals

attached to cell body

sensitive branches that receive info as electrical signals from nerves near it

fatty layer covering axon

helps speed up nerve impulse

protects impulse from “crossing wires”

contains a nucleus

bulb at end of axon

where electrical msg is passed across synapse to next dendrite

small gap between neurons

detects change in environment

e.g. photoreceptors detecting light

change in environment

enhances or amplifies changes

dampens or buffers changes

receptor (sensor), the control centre, and effectors.

helps prevent damage and injuries to the body

1. stimulus

2. sensory receptor detect change

3. sensory neuron carries signal from receptor to spinal cord

4. interneuron relays signal from sensory neuron to motor neuron

5. motor neuron carries signal to effector cells

6. effector cell causes response

1. stimulus

2. sensory receptor detects change

3. sensory neuron carries signal from receptor to CNS

4. CNS processes info, makes decision

5. motor neuron carries response signal to effector cells

6. effector cells cause response

slower, more complex reactions to stimuli

involves brain, spinal cord and peripheral nerves

fast, simple, automatic, involuntary responses to stimuli

involves peripheral nerves, often spinal cord (not brain)

caused by gradual dmg to neurons in brain

affects ability to remember + carry out normal activities

1. pancreas receptors detect inc. blood sugar lvl

2. pancreas stimulates, secretes insulin in blood

3. insulin travels to insulin receptors on muscle + liver cells

4. muscle + liver cells remove excess glucose from blood, stored as glucagon

5. blood sugar lvls dec.

1. pancreas receptors detect dec. blood sugar lvl

2. pancreas stimulated to secrete glucagon into blood

3. glucagon travels to glucagon receptors on muscle + liver cells (target cells)

4. these cells release glucose into blood

5. blood sugar lvls inc.

chemical messengers used to carry info

glands secrete hormones

responsible for growth, repair, digestion, sexual reproduction, homeostasis

nerve tissues

pituitary gland

links nervous system to endocrine

thyroid stimulating hormone (TSH)

growth hormone

controls rate of thyroxin released

stimulates muscle growth + bone size

prepares body for “flight or fight” response

causes immediate release of energy

female sexual development, maintenance of pregnancy

male sexual development + activity (sperm)

thyroxine

regulation of chemical reactions in cells e.g. respiration (metabolism)

insulin

glucagon

control blood sugar levels

hypothal. constantly checks internal environment. if the conditions change, it responds by secreting hormones to the pituitary gland, which then responds to the information by secreting other hormones or producing fewer.

conditions within tissues, organs and systems

pancreas progressively decreases insulin produced until there’s none at all

pancreas makes insulin but cells don’t respond to it as they should (insulin resistance)

physical barriers

prevents pathogens from entering body

skin, saliva, eyes (tears), mucus membrane (trap), acid (stomach), reflexes

innate immune response

1. broad response

2. wbc get involved

blood clotting, inflammation, fever

prevents pathogens entering through damaged skin

increased no. of wbc reaching infected area (becomes red, hot)

destroys weaker pathogens that can’t handle the heat

• neutrophils

• macrophages

wbc arrive in blood, eat any foreign substances

phagocytosis, die, become pus

phagocytosis, present particles to next defence line

adaptive immune response

wbc in this line are made to target specific pathogens

• b-cells

• t-cells

• produce antibodies

• antibodies fit exactly on specific ptg to prevent spreading + help t-cells

attack + destroy specific, recognised pathogens

• bacteria

• virus

• parasites

• fungi

• single celled, living organisms

• some killable w/ antibiotics

• e.g. necrotising faciitis (flesh eating disease)

• much smaller than bacteria, non-living

• insert selves into cells, use body’s DNA to replicate + spread

• e.g. ebola, covid

• organism, lives on another host organism

• benefits from nutrients causing harm to host organism

• e.g. malaria

• caused by fungus

• feed off a protein in skin, nails, hair etc

• red + itchy skin

• most harmless, easily treated

• e.g. ringworm

made with killed/weakened versions of the disease-causing germs/parts of germs (antigens)

each pathogen has a specific antibody that acts on it

1st time we’re exposed, our body is slow to make antibodies to fight it

2nd time, antibodies are made much faster + pathogen destroyed because you’re immune

• adaptive defence has memory b&t-cells made especially for the disease

• cells remember disease if it enters our body again + kills it very quickly

disease causing micro-organisms

anything that causes your body to stop working properly

diseases that can be spread

diseases easily spread

→ passed by touching infected person/items touched by them