Human Biology Y9

Biology Year 9 Semester 1

Diffusion

Movement from high to low concentration areas.

Equilibrium

State where substance is evenly dispersed.

Fluid Movement

Particles constantly move in fluids.

Diffusion Examples

Perfume scent spreading in air.

Diffusion in Water

Cordial mixing evenly in water.

Oxygen Diffusion

Oxygen moves from lungs to blood.

CO2 Diffusion

Carbon dioxide moves from blood to lungs.

Diffusion in Air

Gas particles spreading in the atmosphere.

Diffusion Process

Continuous movement until equilibrium is achieved.

Metabolism

All chemical reactions involved in maintaining the living state of the cells and the organism.

Anabolic reactions

Reactions where energy is stored.

Catabolic reactions

Reactions where energy is released.

Enzymes

Proteins that speed up reactions that occur in living systems.

Lock and key model

Enzymes have an active site that is complementary to only one substrate.

Factors affecting enzyme activity

Enzymes have a specific set of conditions that will favour their action on the substrate and where they function optimally.

Denaturing

The process where the enzyme shape changes, preventing it from functioning.

Temperature effects on enzymes

If temperatures are too high, the enzyme shape changes, preventing it from functioning. If temperatures are too low, the enzyme has not got enough kinetic (movement) energy to collide with the substrates as often and therefore action is reduced.

pH effects on enzymes

The rate of reaction increases to the optimum (maximum) point and then decreases either side of this.

Digestion

Breaking down complex molecules into simple nutrients that the body can use.

Carbohydrates breakdown

Carbohydrates are broken down into glucose.

Proteins breakdown

Proteins are broken down into amino acids.

Lipids breakdown

Lipids are broken down into fatty acids and glycerol.

Rate of reaction with increased enzymes

The rate of reaction increases. The reaction will stop when all of the substrates have been turned into products.

Rate of reaction with increased substrates

The rate of reaction increases until all of the available active sites are filled (substrates have to wait until an active site becomes available).

Endocrine System

Controls specific functions of the human body by the use of chemical substances called Hormones produced in various endocrine glands.

Pituitary Gland

Controls other glands; secretes a variety of hormones, is linked to the nervous system by the hypothalamus

Role of the Hypothalamus

Checks internal environment, responds to changes, links nervous system to endocrine system by secreting hormones which act on the pituitary gland.

Processes Controlled by Hypothalamus

Controls body temperature, metabolism, water levels.

Role of the Pituitary Gland

Secretes a variety of hormones and controls other glands.

Endocrine Glands

Testis, Pancreas, Thymus, Adrenal, Hypothalamus, Thyroid & parathyroid, Pituitary, Ovary.

Hormones

Instructs cells to make changes that restore the body-balance.

Brain

Organ responsible for behavior and regulation.

Nervous System

System coordinating body responses via neurons.

Central Nervous System (CNS)

Includes brain and spinal cord; control center.

Peripheral Nervous System (PNS)

Nerves outside CNS; connects body to CNS.

Brainstem

Relay station for messages between body and brain.

Cerebellum

Coordinates movement, balance, and posture.

Cerebrum

Largest brain region; divided into two hemispheres.

Hemispheres of the Brain

Two halves; left controls right side, vice versa.

Motor Neurons

Carry messages from CNS to muscles or glands.

Sensory Neurons

Transmit signals from sense organs to CNS.

Neurotransmission

Chemical communication between neurons via neurotransmitters.

Synapse

Space between axon and dendrites for neurotransmission.

Somatic Nervous System

Controls voluntary muscle movements.

Autonomic Nervous System

Regulates involuntary muscle movements.

Sympathetic Nervous System

Prepares body for fight or flight response.

Parasympathetic Nervous System

Restores body functions; promotes relaxation.

Reflex Action

Automatic response to stimuli, bypassing brain.

Stimulus

Change detected by sensory organs.

Neurons

Specialized cells transmitting electrical impulses.

Neurotransmitters

Chemicals released for neuron communication.

Effectors

Muscles or glands responding to motor neuron signals.

Receptors

Nerve endings detecting environmental changes.

Five Senses

Sight, hearing, touch, taste, smell.

Reflex Examples

Knee-jerk, withdrawal from pain, blinking.

anabolic

a process involving chemical reactions that produce complex molecules from simpler substances

axon

a nerve fibre that sends nerve impulses away from the cell

brain stem

the part of the brain where the spinal cord enters the skull; it controls the body's vital functions such as breathing, blood pressure and heart rate

catabolic

a process involving chemical reactions that breaks down complex molecules into smaller ones

cell body

the part of the neuron that contains the nucleus

central nervous system (CNS)

the brain and spinal cord

cerebellum

the part of the brain that is responsible for coordination and balance

effectors

muscles or glands that put the messages into effect

endocrine glands

glands that produce hormones

endocrine system

all the endocrine glands of the body

endothermic

able to maintain a constant body temperature

cerebrospinal fluid (CSF)

a fluid surrounding the brain and spinal cord, which provides nutrients to the neurons and acts as a shock absorber

cerebrum

the part of the brain that controls conscious thoughts, and the movement of every body part, and receives sensory messages from each body part

connector neurons

these neurons transmit messages between neurons in the CNS

cranium

a bony structure that surrounds the brain

dendrites

branches from the cell body that receive messages from other neurons

diffusion

the movement of particles of a substance from an area of high concentration to an area of low concentration

ectothermic

animals that rely on environmental temperature to regulate body temperature.

enzyme

a protien that speeds up a rate of reaction

feedback system

body systems regulate themselves by monitoring and self-correction adjusting output depending on stimulus

homeostasis

the process of maintaining a constant internal environment

hormones

chemical substances that act as messengers in the body

hypothalamus

a portion of the brain that constantly checks the internal environment of the body

medulla

the lower half of the brain stem

metabolism

all the chemical reactions occurring in the cells

mitochondria

organelles where cellular respiration occurs

motor neurons

nerve cells that carry messages from the CNS to effectors

myelin sheath

the insulating layer that covers a neuron

ribosome

the structure where proteins are manufactured

nerve impulse

the electrical message carried by a nerve cell

neuron

a nerve cell

neurotransmitter

a chemical message released at the end of an axon to be received by the next neuron's dendrites

peripheral nervous system (PNS)

the nerves that carry messages to and from the central nervous system and other parts of the body

pituitary gland

the endocrine gland that controls the activities of other endocrine glands; it is often called the 'master gland'

receptor

a specialised cell that detects stimuli (changes)

reflex actions

quick, automatic actions that protect the body from danger; also known as reflexes

reflex arc

the nerve pathway operating in a reflex action

sensory neurons

nerve cells that carry messages from cells in the sense organs to the CNS

stimulus

any factor that stimulates a receptor and brings about a response

substrate

the molecule that is going to be changed by a chemical reaction involving an enzyme

synapse

the space between two neurons

target cells

the cells on which a hormone acts

vertebrae

bones that surround the spinal cord and provide attachment for muscles