Organism Level Systems

ADH

ADH

A hormone secreted by the pituitary gland which increases water reabsorption in the kidney (making the kidney tubules more permeable to water)

Adrenaline

• A hormone released by the adrenal gland which increases heart rate and breathing rate (involved in fight/flight).

• It also raises blood sugar levels by increasing the conversion of glycogen into glucose

Auxin

A plant hormone that is responsible for cell elongation

Central Nervous System (CNS)

The brain and the spinal cord

Cerebellum

The region of the brain that controls unconscious functions such as posture, balance, and muscular movement

Cerebral Cortex

The outer layer of the cerebrum

Cerebrum

• The highly folded region of the brain that is responsible for controlling voluntary actions such as learning, personality, and memory.

• It is divided into the right and left hemispheres

Ciliary Body

• An extension of the iris

• It contains the ciliary muscle which can contract or relax allowing the eye to focus

Colour Blindness

A condition where a person has a defect in the receptors or a lack of receptors in the retina

Contraception

Methods that are used to prevent pregnancy

Cornea

The part of the eye that refracts light as it enters, focusing it onto the retina

Dormancy

• A period of time in which seeds hibernate

• This stops when they germinate

Effector

A gland or muscle that produces a response to the stimulus to restore optimum conditions

Endocrine Glands

A group of cells that are specialized in secreting chemical (hormones) directly into the bloodstream

Endocrine System

A chemical messenger system that releases hormones directly into the bloodstream to control metabolism, development, growth, and reproduction

Ethene

A plant hormone that promotes fruit ripening

Follicle Stimulating Hormone (FSH)

• A female reproductive hormone that is released by the pituitary gland

• It is responsible for the maturation of an egg in the ovary

Geotropism

The growth response of a plant to gravity

Germination

The process by which seeds develop into plants

Gibberellins

Plant hormones that initiate germination and flowering

Glucagon

• A hormone produced by the pancreas which works with insulin to control blood sugar levels.

• It increases blood glucose concentration by converting glycogen into glucose

Herbicide

A type of pesticide used to kill unwanted plants (weeds)

Homeostasis

• The maintenance of a stable internal environment in the body despite fluctuations in internal and external conditions

Hormone

A chemical messenger secreted by the endocrine glands into the bloodstream and transported to receptors on target organs

Hypothalamus

The part of the brain that is the regulation center for temperature and water balance of the body

Infertility

The inability to reproduce after 12 months or more of unprotected sex

Insulin

• A hormone produced by the pancreas which controls the body’s blood sugar levels

• It works to decrease glucose levels

In Vitro Fertilization (IVF)

• The fertilization of an egg using sperm outside of the body

• IVF is used when a couple are having difficulty conceiving

Iris

The part of the eye that contracts or relaxes to control the amount of light entering the eye

Kidney

The organ in the body that maintains water balance and produces urine

Lens

A part of the eye that further refracts light to focus it onto the retina

Long-Sightedness (Hyperopia)

A defect of the eye where distant objects appear out of focus due to the convergence of light rays in front of the retina

Luteinizing Hormone (LH)

A female reproductive hormone released by the pituitary gland that stimulates the release of an egg

Medulla

The part of the brain responsible for non-voluntary movement such as breathing rate and heart rate

Menstrual Cycle

The monthly cycle in women that involves the development of the uterus lining, ovulation, maintenance of the uterus lining and it shedding

Motor Neuron

The neuron that transmits impulses from the relay neuron to the effector to produce a response

Negative Feedback System

A system which works to reverse the initial stimulus

Nephron

A kidney filtering unit

Estrogen

A female sex hormone produced in the ovaries that regulates the menstrual cycle and controls the development of secondary sexual characteristics

Optic Nerve

The nerve that carries impulses between the brain and the eye

Osmosis

The net movement of water molecules from a region of high water concentration to a region of low water concentration across a partially permeable membrane

Osmotic Lysis

When water moves into an animal cell causing it to burst

Osmotic Shrinking

When water moves out of an animal cell causing the cell to shrink

Parthenocarpic Fruit Development

The development of seedless fruit

Phototropism

The growth response of a plant to unilateral light

Pituitary Gland

The gland that stores and releases hormones which regulate many bodily functions

Progesterone

The hormone that maintains the uterus lining during the later stages of the menstrual cycle and pregnancy

Pupil

A hole in the center of the iris

Receptor

A cell or organ that recognizes the stimulus

Reflex Arc

The pathway of neurons involved in a reflex action

Relay Neuron

The neuron that transmits electrical impulses from the sensory neuron to the motor neuron

Renal Artery

The blood vessel that provides the kidney with blood

Renal Vein

The blood vessel that takes blood away from the kidney

Retina

The layer at the back of the eye that contains light receptors and is sensitive to light

Root Cuttings

A method of cloning plants in which a root is cut from a parent plant and replanted in compost

Rooting Powder

• A powder that contains auxins

• The cut root is dipped into this before being replanted (during root cuttings)

Sensory Neuron

The neuron that detects the stimulus and transmits the electrical impulse to the relay neuron located in the spinal cord

Short-Sightedness (Myopia)

A defect of the eye where distant objects appear out of focus due to the convergence of light rays in front of the retina

Suspensory Ligaments

Attach the lens to the ciliary muscle

Synapse

The junction between two neurons (nerve cells)

Testosterone

The male reproductive hormone that controls sperm production and the development of the secondary sexual characteristics

Thyrozine

• A hormone released by an endocrine gland (thyroid gland) that controls the metabolic rate and the rate of glucose uptake during respiration

• It also promotes growth

Tissue Culture

A method of cloning plants where plants are grown in a growth medium containing many nutrients

Type 1 Diabetes

A condition in which the pancreas fails to produce insulin resulting in high blood sugar levels

Type 2 Diabetes

A condition in which a person develops insulin resistance or doesn’t produce enough insulin

Urine

• Liquid produced by the kidneys to help maintain water balance

• It contains mineral ions, water, and urea

Vasoconstriction

The constriction of blood vessels

Vasodilation

The dilation of blood vessels

Water Potential

• A measure for the tendency of water to move from one area to another

• It is represented by the Ψ (Psi)

Brain and the Spinal Cord

The central nervous system (CNS) consists of the ___ and ___

Central Nervous System (CNS)

It allows us to make sense of our surroundings and respond to it in order to survive

Receptor cells

(How the Nervous System Coordinates Responses)

___ ___ convert a stimulus (such as a bright light) into an electrical impulse

Sensory Neurons

(How the Nervous System Coordinates Responses)

This electrical impulse travels along cells called ___ ___ to the central nervous system (CNS)

Electrical Impulse

(How the Nervous System Coordinates Responses)

Here, the information is processed and the appropriate response is coordinated, resulting in an ___ ___ being sent along motor neurons to effectors

Effectors

(How the Nervous System Coordinates Responses)

The ___ carry out the response (this may be muscles contracting or glands secreting hormones)

Reflex Arc

• A subconscious response to a dangerous stimuli, such as a hot surface

• Sometimes an extremely quick response is needed and there is not enough time for it to go through the conscious portion of brain so the CNS is involved instead

Stimulus

(Reflex Arc)

• A ___ is detected by receptors, such as thermoreceptors in fingertips detecting heat

Impulses

(Reflex Arc)

___ are sent along a sensory neuron

Relay neuron

(Reflex Arc)

In the CNS the impulse passes to a ___ ___

Motor Neuron

(Reflex Arc)

Impulses are sent along a___ ___

Effector

(Reflex Arc)

The impulse reaches an ___ resulting in the appropriate response, such as a contraction of the biceps to move the arm away from the heat source

Cornea

(Structures of the Eye)

• The transparent outer part of the eye

• It refracts light to reach the retina

Iris

(Structures of the Eye)

• The colored part of the eye that does not allow light to go through

  Controls how much light enters the eye

• In bright light, the circular muscles contract and radial muscles relax to make the pupil smaller, avoiding damage to the retina

• In dim light, the circular muscles relax and the radial muscles contract to make the pupil larger, so more light can enter to create a better image

Lens

(Structures of the Eye)

• Transparent, biconvex disc that attaches to ciliary muscles by the suspensory ligaments

• Focuses light onto the retina

Retina

(Structures of the Eye)

• Contains light receptors

• Contains rods (respond to dim light) and cones (respond to color)

Optic Nerve

(Structure of the Eye)

• Carries impulses between the eye and the brain

Color Blindness

(Eye: Common Defects)

• The inability to tell the difference between different colors due to the lack of or defects in the receptors in the retina

• It is an inherited condition and the most common form is red-green color blindness

Myopia (Short-Sightedness)

(Eye: Common Defects)

• The ability to see near objects but not distant objects, due to the lens focusing the image in front of the retina.

• They are treated by concave lenses in glasses

Hyperopia (Long-Sightedness)

(Eye: Common Defects)

• Ability to see distant objects but not near objects, due to the lens focusing the image behind the retina

• They are treated by convex lenses in glasses

Cerebrum

(Structure of the Brain)

• Functions

  • Intelligence

  • Vocabulary

  • Personality

  • Conscious Thought

Cerebrum

(Structure of the Brain)

• Features

  • The largest part of the brain and divides into 2 cerebral hemispheres

  • Each half processes the information it receives from the opposite side of the body

  • The outside is made from grey matter (containing myelinated nerves) and the inside is made of white matter

Cerebellum

(Structure of the Brain)

Coordinate voluntary body movements and help with balance

Medulla

(Structure of the Brain)

Control center for heart rate, blood pressure, and breathing rate

Hypothalamus

(Structure of the Brain)

Control temperature and water balance in the body through the hormonal system

Pituitary gland

(Structure of the Brain)

An important gland releasing hormones, such as growth hormone into the blood

Endocrine System

• Hormones are chemical messengers that are secreted by endocrine glands into the bloodstream, where they are transported around the body to receptors on the target organ

• The pituitary gland, mentioned before, it one of the most important glands

Adrenaline

• Produced by the adrenal glands that sit on top of kidneys

• Targets many different organs, such as the heart and lungs

• Responsible for the ‘fight or flight’ response for survival

  • Increases heart rate, dilates pupils, makes hairs stand erect, increasing breathing rate

Thyroxine

• Produced by thyroid gland in the neck

• Responsible for controlling metabolic rate, meaning it controls how quickly oxygen and food react to release energy. It is therefore responsible for growth.

• Example of negative feedback

  • If ___ levels are too low it stimulates the hypothalamus to produce a hormone called TRH and the pituitary then releases TSH (thyroid stimulating hormone) which causes the thyroid to produce more ___.

  • When the levels are returned to normal these hormones are inhibited to stop further increases.

Hormones

___ are responsible for controlling puberty and also the menstrual cycle

Testosterone

(Puberty)

• Produced by the testes, are responsible for the development of sperm and also secondary sexual characteristics in males, such as deepening voices and increased hair.