Homeostasis and Response

Homeostasis

Homeostasis

The regulation of internal conditions to maintain optimal conditions for enzyme action and cell function, involving control of blood glucose concentration, body temperature, and water levels through automatic control systems.

Human Nervous System

Enables reactions to surroundings and coordination of behavior, consisting of the central nervous system (CNS) and peripheral nervous system, with reflex arcs for immediate responses to stimuli.

Central Nervous System (CNS)

The brain and spinal cord

Peripheral Nervous System

the nerve cells that carry information to or from the CNS

Ganglion

A cluster of nerve cells found in the peripheral nervous system

Reflex Arc

A neurological and sensory mechanism that controls a reflex, an immediate response to a particular stimulus

Reflex actions

Actions that are are automatic and rapid; they do not involve the conscious part of the brain.

Sensory Neurone

The nerve cells activated by sensory input from the environment

Synapse

Connect neurons and help transmit information from one neuron to the next

Relay Neurone

(found in the brain and spinal cord) allows sensory and motor neurons to communicate

Motor Neurone

(found in the CNS) controls muscle movements

The Brain

A complex organ controlling various functions like thought, memory, emotion, and motor skills, with structures including the cerebral cortex, cerebellum, medulla, hypothalamus, and pituitary gland.

Cerebral Cortex

Outer layer of the brain’s surface that carries out essential functions such as memory, thinking, learning, reasoning, problem-solving, emotions, consciousness, and sensory functions

Cerebellum

Responsible for coordinating movement and balance

Medulla

Manages heart, circulation and breathin

Hypothalamus

Helps manage your body temperature, hunger and thirst, mood, sex drive, blood pressure and sleep

Pituitary gland

Monitors and regulates many bodily functions through the hormones that it produces

The Eye

A sense organ containing receptors sensitive to light intensity and colour

Suspensory Ligament

A series of fibres that connect the ciliary body of the eye with the lens, holding it in place

Cornea

Acts as the outermost lens and functions like a window that controls and focuses the entry of light into the eye

Iris

The coloured tissue of the eye that controls the size of the pupil to let more or less light into the eye

Pupil

The opening in the centre of the iris that allows light to enter the eye so it can be focused on the retina to begin the process of sight

Ciliary body and muscle

The ciliary body produces aqueous humour. It also contains the ciliary muscle, which changes the shape of the lens when your eyes focus on a near object

Lens

Its function is to transmit and focus light onto the retina

Sclera

The white outer coating of the eye that maintains your eye's shape and protects it from injuries

Retina

It converts light that enters your eye into electrical signals your optic nerve sends to your brain which creates the images you see

Fovea

A small depression within the neurosensory retina where visual acuity is the highest

Optic Nerve

It transmits electrical impulses from your eyes to your brain

Accommodation

The process of changing the shape of the lens to focus on near or distant objects

Two Common Defects of the Eye

Myopia and Hyperopia

Myopia

short-sightedness

Hyperopia

long-sightedness

Body Temperature

A measure of how well your body can make and get rid of heat

Thermoregulatory Centre

Contains receptors sensitive to the temperature of the blood

Hormones

Are chemical messengers that enter the blood directly upon their secretion from endocrine glands

Hormonal Coordination

Involves the interaction between hormones and target cells or tissues, which regulate functions such as metabolism, growth, reproduction, and stress response

Endocrine System

Composed of glands which secrete chemicals called hormones directly into the bloodstream

Blood Glucose Concentration

Monitored and controlled by the pancreas which is measured from capillary blood obtained from a finger prick

Insulin

A hormone that tells cells throughout your body to take in glucose from your bloodstream

Diabetes

A chronic disease that occurs either when the pancreas does not produce enough insulin or when the body cannot effectively use the insulin it produces

Types 1 Diabetes

A disorder in which the pancreas fails to produce sufficient insulin

Types 2 Diabetes

A disorder where the body cells no longer respond to insulin produced by the pancreas

Osmosis Changes

(shock or stress) is a physiologic dysfunction caused by a sudden change in the solute concentration around a cell, which causes a rapid change in water movement across its cell membrane

Kidney

One of a pair of organs in the abdomen that removes waste and extra water from the blood (as urine) and helps keep chemicals (such as sodium, potassium, and calcium) balanced in the body

Kidney Failure

One or both of your kidneys no longer function well on their own

Kidney Dialysis

Treatment for kidney failure involving the removal of waste products from the blood, with advantages like normal life and disadvantages like lifestyle impacts.

Reproductive Hormones

A hormone involved in puberty, fertility, and sexuality, with hormones like oestrogen and testosterone regulating secondary sex characteristics and the menstrual cycle

Puberty

The process of physical maturation where an adolescent reaches sexual maturity and becomes capable of reproduction

Oestrogen

The main female reproductive hormone produced in the ovary. At puberty, eggs begin to mature and one is released approximately every 28 days (ovulation)

Testosterone

The main male reproductive hormone produced by the testes and it stimulates sperm production

Hormones Involved in the Menstrual Cycle

Follicle stimulating hormone (FSH), Luteinising hormone (LH), and Ostrogen and Progesterone.

Follicle stimulating hormone (FSH)

Causes maturation of an egg in the ovary

Luteinising hormone (LH)

Stimulates the release of the egg

Oestrogen and Progesterone

Involved in maintaining the uterus lining

Contraception

Methods to control fertility, including hormonal methods like injections and oral contraceptives, and non-hormonal methods like barriers and surgical sterilization

Hormonal Contraceptive Methods

• Injection, Implant, and Skin Patches

• Intrauterine Device (IUD)

• Oral Contraceptives (Pills)

Non-Hormonal Contraceptive Methods

• Permanent Sterilisation (surgical method)

• Chemical/Physical Barriers (spermicides and condoms) 

• Withdrawal and Rhythm Method

Plant Hormones

Regulate growth and responses to light and gravity in plants, with auxin stimulating cell elongation and being used for various purposes like weed killers and growth promotion.

Auxin

Any of a group of plant hormones that regulate growth, particularly by stimulating cell elongation in stems