Year 9 bio

Definitions and Functions

Specialised cell

A cell with a specific structure and function that performs a particular job.

Neuron (nerve cell)

A specialised cell that sends and receives electrical signals.

Afferent Neurons

carry sensory information towards the CNS

Efferent Neurons

carry motor signals away from the CNS to effectors

Function of Neuron

Receive signals, interpret incoming signals and transmit the message and communicate and send the information to target cells

Multicellular organism

An organism made of many cells that work together.

Muscle cell (myocyte)

Long thing elastic specialised cells that contracts to produce voluntary and involuntary movement.

Skeletal muscle

Muscle attached to bones for voluntary movement.

Smooth muscle

Muscle in organs that works involuntarily.

Cardiac muscle

Muscle in the heart that pumps blood.

Plant cell

A cell with a cell wall, chloroplasts and vacuole.

Cell wall

A rigid outer layer that supports plant cells.

Gamete

A reproductive (sex) cell such as sperm or egg.

Sperm cell

The male reproductive cell.

Egg cell (ovum)

The female reproductive cell.

Fertilisation

Fusion of sperm and egg to form a zygote.

Zygote

The first cell formed after fertilisation.

Sexual reproduction

Reproduction involving two parents and genetic mixing.

Asexual reproduction

Reproduction from one parent producing identical offspring.

Binary fission

A cell splits into two identical cells.

Budding

A new organism grows from the parent.

Vegetative propagation

Plant reproduction using stems, roots or leaves.

Hormone

A chemical messenger in the body.

Testosterone

Male sex hormone for development and sperm production.

Oestrogen

Female sex hormone for reproductive development.

Nervous system

System that detects and responds to stimuli using signals.

Central nervous system (CNS)

Made up of the brain and spinal cord

Function of CNS: Receives information, processes the information and responds by sending out messages to the body

Receptor

A specialised cell or protein that detects stimuli in the environment and converts them into a signal

Reflexes

automatic involuntary actions produced by the body due to a certain stimulus

Importance of reflexes

protect the body from danger and help with survival, maintains homeostasis

Stimulus

A change or event that triggers a response.

Effector

Carries out an action or response (muscle/gland).

Axon

A long cable-like projection of a neuron that transmits electrical signals away from the neurons cell body to other neurons, glands or muscles

Dendrite

Branching extensions that receive signals from other neurons at synapses

Cell body (soma)

contains the nucleus and controls the cell.

Myelin sheath

A fatty insulating layer known as myelin that insulates the axon and speeds signals.

Axon terminal

End of a neuron that passes signals and forms synapses with other cells

Effector

any part of the body ( typically muscles or glands) that produces a specific response when stimulated by nerve impulses

Synapse

Transmission of signals from one neuron to another across a gap

Synaptic cleft

Small space where signals are transmitted

Neurotransmitter

Travel across the synaptic cleft, triggering the electrical impulse the travel along the second neuron

Sensory neuron

Carries signals from sense organs to the CNS. Activated by sensory input

Motor neuron

Carries signals from the CNS to effectors (muscles, glands, organs)

Relay neuron

Found only in the CNS and connects and transfers signals between motor and sensory in the CNS

Brain

Control centre of the body.

Brain Functions

Controlling body movement, balance and coordination, regulating behaviour and emotions and processing sensory info

Spinal cord

Carries messages between the brain and body, enables movement, sensations and coordinated body functions

Spinal Cord Functions

Transmits sensory Information, independently processes simple reflexes

White matter

Transmits signals in the brain because it contains neurons.

Grey matter

Processes information, contains mainly soma

Cerebrum (how many lobes)

Largest part of the brain has four lobes: Frontal, Parietal, Temporal and Occipital

Function of Cerebrum

Controls thinking and movement.

Cerebellum

Controls balance and coordination.

Brain Hemispheres

Two Halves: Left Hemisphere and Right Hemisphere

Brain Regions

Cerebrum, Cerebellum and Brain Stem

Brainstem

Controls vital functions such as breathing, blood pressure and heart rate

Frontal lobe

Decision making, behaviour and impulse control

Parietal lobe

Processes sensory information.

Temporal lobe

Strong links with Memory, language, emotion.

Occipital lobe

Processes vision.

Cranium

The skull, outer layer (bone)

Cranial

Nerves inside the brain

Peripheral Nervous System

Is made up of all the nerves and sensory structures outside the brain and spinal cord

Function of the Peripheral Nervous System

allow for the CNS to communicate with the sensory organs, muscles and glands

Autonomic Nervous System

regulates involuntary body functions

Two Subdivisions of Autonomic Nervous System

Parasympathetic system and Sympathetic System

Parasympathetic

Known as "rest and digest" system, promotes relaxation and conservation of energy and slows down function of body

Sympathetic

"Fight or Flight" system, produces responses to stressful situations, speeds up body function to work efficiently

Somatic Nervous System

A component of the peripheral nervous system, and is responsible for the voluntary control of body movements

Two main jobs of the Somatic Nervous System

Sensory Input and Movement control

Which senses travel through the Somatic Nervous System

Ears, nose, tongue, and skin travel through the SNS, which relays signals to your brain

Steps of Sensory Stimulus Pathway

1. Stimulus Detection 2. Converts environmental stimulus to electrical signals 3. Signals are transmitted via relay neurons towards CNS and processes response

Reflex Arc Pathway

Is a pathway along which impulses are transmitted from a receptors to an effector without involving conscious regions of the brain

Reflex Arc Pathway steps

1. Receptors in sense organs detect a change in stimulus 2. A sensory neuron sends a nerve impulse to a relay neuron 3. A relay neuron passes electrical signals directly to a motor neuron which sends the impulses to an effector 4. The effector carries out the response 5. A message is sent to the brain afterwards to process after the reflex has been carried out