2nd Semester 39 - BIOLOGY JUNCTION

Algal & Fungal Protist

Algal & Fungal-like Protists
Kingdom Protista
All Materials © Cmassengale

Algal-Like Protists

Characteristics of Algae:

Plantlike members of the kingdom Protista
Eukaryotes
Most unicellular, but some multicellular
Autotrophic – contain chlorophyll & make food by photosynthesis
Plankton = communities of organisms, mostly microscopic, that drift passively or swim weakly near the surface of oceans, ponds, and lakes
Produce oxygen that is returned to the atmosphere
Range in size from microscopic to seaweeds hundreds of feet in length
Do not have true roots, stems, nor leaves
Form gametes (eggs & sperm) in single-celled gametangia (chambers) instead of multicellular gametangia like true plants
Found in freshwater, marine, and moist soil habitats
Most have flagella at some time in life cycle
Algae cells contain organelles called pyrenoids organelles that make & store starch

Structure of Algal Cells:

The body of algae is called the thallus (1n)
Algae may be unicellular, colonial, filamentous, or multicellular
Unicellular algae are single-celled & make up phytoplankton (a population of photosynthetic organisms that begins many aquatic food chains)
Phytoplankton make much world’s carbohydrates & are the major producers of oxygen

Chlamydomonas
Copyright © by Holt, Rinehart and Winston

Colonial algae consist of groups of cells working together
Some colonial algal cells may specialize for movement, feeding, or reproduction showing for division of labor

Volvox
Copyright © by Holt, Rinehart and Winston

Filamentous algae have slender, rod-shaped thallus arranged in rows joined end-to-end
Holdfasts are specialized structures in some filamentous algae that attaches the algae so it can grow toward sunlight at the surface

Spirogyra
Copyright © by Holt, Rinehart and Winston

Multicellular algae often have a large, complex leaf-like thallus & may have stem-like sections and air bladders
Macrocystis is among the largest multicellular algae

Macrocystis
Copyright © by Holt, Rinehart and Winston

Reproduction in Unicellular Algae:

Asexual Phase

Algae absorbs its flagellum
Haploid algal cell then divides mitotically from 2 to 3 times
From 4 – 8 haploid flagellated cells called zoospores develop in this parent cell
Zoospores break out of the parent cell & eventually grow to full size

Sexual Phase

Haploid cells dividing mitotically to produce either “plus” or “minus” gametes
A plus gamete and a minus gamete come into contact with one another, shed their cell walls, and fuse to form a diploid zygote
This resting stage of a zygote is called a zygospore & an withstand bad environmental conditions
When conditions are bad, the thick wall opens and the living zoospore emerges

Life Cycle of Chlamydomonas
Copyright © by Holt, Rinehart and Winston

Reproduction in Multicellular Algae:

Oedogonium is a multicellular, filamentous green algae with specialized cells called gametangia that form gametes
The male gametangia or antheridium makes sperm, & the female gametangia or oogonium makes eggs
Sperm are released into the water & swim to the egg to fertilize them
The fertilized egg or zygote is released from the oogonium & forms thick-walled zoospores
Zoospores undergo meiosis so one cell attaches to the bottom & develops a holdfast while the other zoospores divide & form a filament

Oedogonium Life Cycle
Copyright © by Holt, Rinehart and Winston

Spirogyra, another filamentous green algae, reproduces by conjugation

spirogyra conjugating.jpg (91550 bytes)

Two filaments align side by side, their adjacent cell walls dissolve, & a conjugation tube forms between them
Fertilization occurs when a + gamete cell moves through the tube & fuses to the – gamete cell
Zygote forms a thick walled spore (sporangium) that breaks away from the parent & forms a new filament

Spirogyra: conjugation begining.
Conjugation Tube between Spirogyra

The leaflike algae Ulva has a sexual reproductive cycle characterized by a pattern called alternation of generations
Alternation of generations has two distinct multicellular phases- a haploid, gamete-producing phase called a gametophyte and a diploid, spore-producing phase called a sporophyte
Alternation of Generation also occurs in more complex land plants, but the gametophyte & sporophyte do not resemble each other

Ulva Life cycle
Copyright © by Holt, Rinehart and Winston

Classification:

Algae are classified into 7 phyla, based on color, type of chlorophyll, form of food-storage substance, and cell wall composition
All phyla contain chlorophyll a
All algae live in water or moist areas (ponds, seas, moist soil, ice…)
Act as producers making food & oxygen
Many species of algae reproduce sexually and asexually
Sexual reproduction in algae is often triggered by environmental stress

SEVEN PHYLA OF ALGAE
Phylum	Structure of Thallus	Pigments	Food Storage	Cell Wall composition
Chlorophyta (Green Algae)	Unicellular Colonial Filamentous Multicellular	Chlorophyll a & b Carotenoids	Starch	Mainly Cellulose
Phaeophyta (Brown Algae)	Multicellular	Chlorophyll a & c Carotenoids Fucoxanthin Peridinin	Laminarin	Cellulose Algin
Rhodophyta (Red Algae)	Multicellular	Chlorophyll a Phycobilins Carotenoid	Starch	Cellulose CaCO3
Bacillariophyta (Diatoms)	Unicellular Some Colonial	Chlorophyll a & c Carotenoids Xanthophyll	Starch	Pectin SiO2
Dinoflagellata (Dinoflagellates)	Unicellular	Chlorophyll a & c Carotenoids	Starch	Cellulose
Chrysophyta (Golden Algae)	Unicellular Some Colonial	Chlorophyll a & c Xanthophyll Carotenoids	Laminarin	Cellulose
Euglenophyta (Euglenoids)	Unicellular	Chlorophyll a & b Carotenoids Xanthophyll	Paramylon	No Cell Wall Pellicle

Chlorophyta (green Algae):7000 species

May be unicellular, multicellular, or colonial
Include Spirogyra, Ulva, & Chlamydomonas
Contain chlorophyll a & chlorophyll b and carotenoids (orange & yellow pigments) as accessory pigments
Store food as starch
Cell walls mainly cellulose, but some marine forms add CaCO3
Habitat may be freshwater, moist surfaces, or marine environments
Some have whip-like flagella for movement
May live symbiotically as lichens
Thought to have given rise to terrestrial plants

Phaeophyta (brown algae):1500 species

Contain chlorophyll a & chlorophyll c and fucoxanthin (brown pigment) as accessory pigments
Most are multicellular growing in cooler marine habitats
Include kelps & seaweeds
Largest protists
Specialized rootlike holdfasts anchor thallus to rocks
Specialized air bladders keep leaflike blades afloat near surface to get light for photosynthesis
Stemlike structures are called the stipe and support the blades
Store food as a carbohydrate called laminarin
Include Laminaria & Fucus


Laminaria	Fucus

Macrocystis or giant kelp contains algin in its cell walls which is used in cosmetics, some drugs, ice cream, etc.

Rhodophyta (red algae):4000 species

Multicellular algae that mainly grow deep in warm marine waters
Some freshwater species exist
Highly branched thallus
Contain chlorophyll a & phycobilins (red pigments) to trap sunlight for photosynthesis

Polysiphonia (red algae)

Store food as starch
Cell walls contain cellulose and agar (used as a base in culture dishes to grow microbes)
Some species contain carageenan in their cell walls used for gelatin capsules & in some cheeses

Bacillariophyta (diatoms):11,500 species

Abundant in marine & freshwater habitats
Called phytoplankton & start many aquatic food chains
Contain chlorophyll a & c, carotenoids (orange pigments), & xanthophyll (yellow pigments)
Store food as starch & contain mainly cellulose in their cell walls
Lack cilia & flagella
Have glass like shells or valves containing SiO2 that fit together in 2 parts

Diatoms
Copyright © by Holt, Rinehart and Winston

Centric diatoms are marine & have circular or triangular shells
Pennate diatoms are found in freshwater & have rectangular shells
When diatoms die, they form a layer called diatomaceous earth that is abrasive and used in detergents, toothpaste, fertilizers, etc.

Dinoflagellata or Pyrrophyta (dinoflagellates):1100 species

Major producers in marine habitats
Small, unicellular organisms making up plankton
Many are photosynthetic, but some are colorless heterotrophs
Photosynthetic dinoflagellates are yellow to brown in color due to chlorophyll a & c and carotenoids

Have 2 flagella that spin and move the dinoflagellate through water

Store food as starch
Some dinoflagellates are covered with armor like plates & spines made of cellulose
Often undergo algal blooms where their numbers greatly increase
Produce a toxic substance and cause poisonous red tides (water appears red due to red pigments in the dinoflagellates)

Red Tide

Some such as Noctiluca can produce light by bioluminescence

Photograph by Robert Brons

Chrysophyta (golden algae)850 Species:

Most are live in freshwater habitats, but some are marine
Unicellular algae containing chlorophyll a & c and the brown pigment fucoxanthin and carotenoids
Many have flagella for movement
May be naked or have cellulose cell walls or silica scales or shells
May form highly resistant cysts to survive beneath frozen lake surfaces in winter

Euglenophyta1000 Species:

Unicellular algae that lack cell walls
Have a flexible protein covering called the pellicle
Called euglenoids
Possess chlorophyll a & b and carotenoids
Store food as paramylon (polysaccharide)
Most live in freshwater, but some live in moist soil & the digestive tracts of certain animals

Euglena is a common euglenoid found in freshwater
a. Elastic, transparent pellicle below cell membrane
b. Contractile vacuole to pump out excess water
c. Chloroplasts to make food by photosynthesis
d. Can be heterotrophic in the absence of light

Fungal-Like Protists

Characteristics of Fungal Protists:

Includes cellular slime molds, plasmodial slime molds, & water molds
Unique life cycles with two phases
Multicellular, heterotrophic organisms
Little tissue specialization
Usually small & live in moist or watery habitats
Act as decomposers breaking down dead organic matter

Slime molds:

Shiny, wet appearance
Often brightly colored (yellow or orange)
Have unique life cycles with 2 phases — a mobile feeding stage & a nonmotile reproductive stage

Feeding Stage of Slime Mold
Copyright © by Holt, Rinehart and Winston

Fungal-like in nutrition (absorptive heterotrophs that break down dead organic matter)
May be saprophytes or parasites

Saprophytic Slime Mold

Multinucleate body mass
May have a mobile, ameba-like feeding stage
Make a reproductive structure or fruiting body that produces spores
Often found on decaying wood or leaves

some slime mold fruiting bodies
A is Lycogala epidendrum, B is Comatricha typhoides, C is Badhamia utricularia, D is Dictydium

Two groups of slime molds exist — Cellular slime molds & Plasmodial slime molds
Cellular Slime Molds (Phylum Acrasiomycota)
Plasmodial Slime Molds (Phylum Myxomycota)

Acrasiomycota (Cellular Slime Molds):

Alternate in their life cycle between amoeboid feeding stage & spore-producing fruiting body

Live in freshwater, moist soil
Clump together into masses called pseudoplasmodium whenever little food is available

Cells in the pseudoplasmodium are independent but move together “slug-like”
Pseudoplasmodium settles & forms fruiting body with spores
Spores spread by wind to new location & form individual amoeboid feeding stage

Myxomycota (Plasmodial Slime Molds):

Exist as a plasmodium ( a mass of cytoplasm with many nuclei)
Plasmodium creeps along over decaying material

Decomposes & absorbs plant material as food
When food is scarce, the plasmodium forms stalked fruiting bodies with spores that are resistant to bad environmental conditions
When conditions turn favorable, spores form a new plasmodium

Oomycota (Water Molds):

Fungal-like organism made of branching filaments with cell walls of cellulose

Branching Filaments of Water Mold

Aquatic water molds are parasites on fish forming furry growths on their gills
May act as decomposers in water of dead plants & animals
May be pathogenic to plants
e.g. Phytophthora infestans caused blight in potatoes (Irish Potato Famine in 19th century)
Blight in plants decays & discolors stems & leaves

Blight on Leaves & Potatoes

Water molds reproduce sexually & asexually
Motile zoospores are asexually produced from reproductive structures called sporangium
In sexual reproduction, cells with eggs form tubes to cells with sperm to fertilize & form new branching filaments

Chytridiomycota (Chytrids):

Aquatic protists that form gametes & zoospores
Most are unicellular or filamentous

May be saprophytes (decomposers) or parasites on algae, plants, or insects
May be a link between protists & fungi

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Amphibian

Amphibians All Materials © Cmassengale

Amphibian Evolution:

	Arose from lobe-fined ancestor called Crossopterygians
	Land plants & insects provided new food source
	Had primitive lungs & short, limb like fins for short periods on land
	Appeared during late Devonian
	Icthyostega early amphibian with 4 limbs, lungs, & a tail for swimming

Adaptations:

	Four limbs with claws on digits (toes)
	Lungs instead of gills
	Both internal & external nares (nostrils)
	Three chambered heart (two atria & one ventricle)
	Double loop blood circulation to lungs & rest of body cells

	Skin with keratin (protein) to prevent water loss
	Necks to more easily see & feed
	Most with smooth, moist skin to take in dissolved oxygen
	Some with oral glands to moisten food they eat
	Webbed toes without claws
	Ectothermic – body temperature changes with environment
	Show dormancy or torpor (state of inactivity during unfavorable environmental conditions)
	Hibernate in winter and aestivate in summer
	Aquatic larva called tadpole goes through metamorphosis to adult
	Metamorphosis controlled by hormone called thyroxine

American Toad Tadpole photograph
Tadpole

	External fertilization with amplexus (male clasps back of female as sperm & eggs deposited into water)
	Eggs coated with sticky, jelly like material so they attach to objects in water & do not float away
	Eggs hatch into tadpoles in about 12 days

Eggs

Males with vocal sacs to croak
Digested system adapted to swallow prey whole
Well developed muscular system

Classification:

Anura – frogs & toads
Urodela – salamanders & newts
Apoda – caecilians
Trachystoma – sirens or mud eels

Anuran Characteristics:

Both terrestrial & freshwater species
Tadpole with tail, gills, & two-chambered heart
Adults without a tail, four limbs, & lungs
Frog skin smooth & moist for cutaneous respiration, while toads is rough & warty (poison glands)

Frog

Toad

Long hind limbs for jumping
Long, forked tongue hinged at front of mouth

Urodela Characteristics:

Includes salamanders & newts
Have elongated bodies with a tail & four limbs
Smooth, moist skin for cutaneous respiration
Less able to stay on dry land than anurans

Spotted salamander photograph
Spotted Salamander

Size from a few centimeters long to 1.5 meters
Nocturnal when live in drier areas
Newts are aquatic species

red-spotted newt photograph
Red Spotted Newt

Lay eggs in water or damp soil
Some bear live young
May or may not go through tadpole stage (some hatch & look like small adult)

Apodan Characteristics:

Includes caecilians
Tropical, burrowing, worm like amphibians
Legless
Small eyes & often blind
Eat worms & other invertebrates
Average length 30 centimeters, but can grow up to 1.3 meters
internal fertilization
Female bear live young

Caecilian

Trachystoma Characteristics:

Includes mud eels or sirens
Known as “rough mouth” amphibians
Found in eastern U.S. & southern Europe
Have minute forelimbs & no hindlimbs

Mud Eel or Siren

External Frog Anatomy:

Live double life on land & water
Powerful hind legs for jumping & swimming fold under body when at rest
Bulging eyes to stay submerged but still see predators
Blinking eyelids protect eyes from dust & dehydration
Nictitating membranes clear to moisten eye & see underwater
Internal nostrils or nares allow frog to breathe underwater
Tympanic membranes or eardrums behind each eye transmit sound through bone called columella to inner ear
Eustachian tubes connect mouth & middle ear to equalize pressure

Males croak or make sound to attract females & ward off other males
Have protective coloration from cells called chromatophores
Granular glands secrete foul tasting or poisonous substance
Mucus glands lubricate skin for oxygen to be dissolved & absorbed

Internal Frog Anatomy:
Skeletal System

Nine spinal vertebrae (1 cervical in neck, 7 trunk, & 1 sacral supporting hind legs)
Urostyle long, slim bone connecting sacral vertebrae & trunk
No rib cage, but pectoral girdle forms shoulders & connects front legs
Pelvic girdle connects to hind legs

Digestive System

Tongue sticky, forked, & hinged at front of mouth so can be extended out to catch insects
Can pull eyes inward to help swallow food
Two, sharp, backward-pointing vomerine teeth in roof of mouth help prevent prey from escaping
Maxillary teeth line the edge of the upper jaw
Alimentary canal (mouth, esophagus, stomach, small & large intestines, and cloaca) is where food is digested, absorbed & wastes eliminated
Stomach makes gastric juices to break down food
Pyloric sphincter muscle controls movement of food from stomach into first part of small intestine called duodenum
Liver makes bile to digest fats; stored in gall bladder
Pancreas makes pancreatic juice to digest food in small intestine
Ileum is coiled mid portion of small intestine
Mesentery is a fanlike membrane holding the intestine in place
Wastes collect in large intestine & then move into cloaca along with eggs, sperm, & urine until they leave body through the anus

Circulatory System

Need more oxygen to burn increased amount of food needed to live on land
3 chambered heart (right atrium receives deoxygenated blood from body, left atrium receives oxygenated blood from lungs, & ventricle pumps blood to lungs & rest of the body)
Double loop blood circulation (pulmonary from heart to lungs & systemic from heart to rest of body)
Conus arteriosus carries blood from ventricle to body cells

Respiratory System

Tadpoles use gills to breathe
Adult frogs breathe through lungs & moist skin (cutaneous respiration)
Glottis is the opening into throat & lungs

Excretory System

Carbon dioxide excreted through skin & lungs
Kidneys filter blood & store urine in urinary bladder until leaves cloaca

Nervous System

Olfactory lobes at base of brain detect smells
Cerebrum behind olfactory lobes controls muscles
Optic lobes detect sight
Cerebellum controls balance & coordination
Medulla oblongata controls heart rate & breathing
Cranial nerves connect brain & spinal cord, while spinal nerves branch off the spinal cord to muscles & sensory receptors

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Sponge Coloring Diagram and Questions

Found at the Biology Corner Name __________________ Period ______

Sponges – A Coloring Worksheet

Since sponges look like plants, it is understandable why early biologists thought they were plants. Today, we know that sponges are simple, multicellular animals in the Kingdom Animalia, Phylum Porifera. This phylum is thought to represent the transition from unicellular animals to multicellular animals. Most (but not all) sponges are asymmetrical and have no definite shape. Sponges, like all animals, are eukaryotic – meaning their cells have a nucleus. Porifera in Latin means “pore-bearer” and refers to the many pores or openings in these animals. Because of these pores, a sponge can soak up and release water. At one time, real sponges were used for cleaning and bathing. Today, most are artificially made.

All adult sponges are sessile, meaning they are attached to some surface. Since they cannot move, sponges cannot pursue their food. Instead, they are filter feeders, meaning they obtain their food by straining the water for small bits of food like bacteria, algae or protozoans.

Sponges exhibit less specialization (adaptation of a cell for a particular function) of cells than most invertebrates. The primitive structure of a sponge consists of only two layers of cells separated by a non-living jelly like substance. The outer layer of the sponge is the epidermis which is made of flat cells called epithelial cells. Color all the epithelial cells (B) of the epidermis peach or pink.

The inner layer consists of collar cells (A) whose function is to circulate water through the sponge. They do this by swishing their flagella which pulls water through the incurrent pore – water then travels out the osculum at the top of the sponge. As water passes through the sponge in this way, cells absorb food and oxygen and waste is excreted. Color the osculum (D) dark blue, the incurrent pores (C) light blue. Color the inside of the sponge where water circulates the same light blue as you colored the incurrent pores. Color all the collar cells (A) red.

In the jelly-like substance between the epidermis and the collar cells are cells called amebocytes – because they look like amebas. The job of the amebocytes is to travel around distributing food and oxygen to the cells of the epidermis. Because of the amebocytes, scientists believe that sponges evolved from protists. Color all of the amebocytes (E) green – look for them carefully.

The body of the sponge would collapse if it did not have some type of supporting structure. Some sponges have a soft network of protein fibers called spongin. Others have tiny, hard particles called spicules. Many of these spicules also stick out of the epidermis and provide the sponge with protection. Most sponges have a combination of spicules and spongin, the ratio often determines how soft or hard the sponge is. Search for and color all the pointy spicules (F) brown.

Reproduction for sponges can be accomplished both sexually and asexually. There are three ways for a sponge to reproduce asexually: budding, gemmules, and regeneration. Sponges can simply reproduce by budding, where a new sponge grows from older ones and eventually break off. Color the adult sponge (J) pink and all the buds (G) you can find red. Sponges can also reproduce by regeneration, where missing body parts are regrown. People who harvest sponges often take advantage of this by breaking off pieces of their catch and throwing them back in the water, to be harvested later. Finally, sponges can reproduce by creating gemmules – which is a group of amebocytes covered by a hard outer covering. Color the gemmule (H) yellow.

Sexual reproduction occurs when one sponge releases sperm into the water. This sperm travels to another sponge and fertilizes its eggs. The larva form will then swim to another location using its flagella where it will grow into an adult sponge. Most sponge species are hermaphrodites, they can produce both eggs and sperm.

Questions:

1. What did early biologists think sponges were? ______________________

2. Sponges belong to the Kingdom _________________ and the Phylum _______________

3. Sponges are [ unicellular or multicelluar ] and [ prokaryotic or eukaryotic ]

4. What type of symmetry do sponges have? ___________________________________

5. What does it mean to be sessile? ____________________________________

6. How do sponges get their food? ___________________________________

7. Water enters the sponge through the _____________________ and leaves through the
_____________________.

8. What is the job of the amebocyte? ________________________________________

9. What two substances give the sponge support? _________________________________

10. Tiny sponges growing from the main body of the sponge are called _________________

11. What is a gemmule? ___________________________________________________

12. What is a hermaphrodite? ______________________________________________

Label the letters on the diagrams

SciSpongesColoringWSP3.bmp (1403574 bytes)

Label the letters on the diagrams
SciSpongesColoringWSP4.bmp (2585142 bytes)

Found at www.biologycorner.com

Endocrine System

The Endocrine System

Click here to view an animation of the endocrine system

The endocrine system is a set of hormone secreting glands within the body of an animal. The function of the endocrine system is homeostasis, communication and response to stimuli. The endocrine system regulates the internal environment of the animal for growth, survival and reproduction as well as allowing it to respond to changes in its external environment.

The endocrine system’s glands secrete chemical messages we call hormones. These signals are passed through the blood to arrive at a target organ, which has cells possessing the appropriate receptor. Exocrine glands (not part of the endocrine system) secrete products that are passed outside the body. Sweat glands, salivary glands, and digestive glands are examples of exocrine glands.

The other communication method in the body is the nervous system. Although there are differences between them, they complement each other in many responses, e.g., response to danger.

The difference between nervous and endocrine control are as follows:

1. Nervous response is faster.

2. Nervous response is shorter in duration.

3. Nervous response stops quicker.

Nervous response is much more local.
Nerve ‘messages’ are conducted electrically; endocrine ‘messages’ are carried chemically.

Hormones

Most hormones are made of protein. They are called peptides. Peptides are short chains of amino acids; most hormones are peptides. They are secreted by the pituitary, parathyroid, heart, stomach, liver, and kidneys.

Some hormones are steroid based. Steroids are lipids derived from cholesterol. Testosterone is the male sex hormone. Estradiol, similar in structure to testosterone, is responsible for many female sex characteristics. Steroid hormones are secreted by the gonads, adrenal cortex, and placenta.

Hormones are usually slow to act but, once they act, they remain active for long periods of time and, also, their effects remain for a long time.

Endocrine Glands

There are 10 endocrine glands. As stated previously, other organs such as the stomach, intestines, kidneys, heart, brain, and placenta also make hormones.

Click here to take an online quiz on the location of the endocrine glands

The Pituitary Gland

The pituitary gland is often called the master gland. That is because the pituitary gland produces hormones that regulate other endocrine glands. Some hormones produced by the pituitary gland are:

1. Follicle Stimulating Hormone (FSH): Will be discussed in a later Chapter of the syllabus.

2. Luteinising Hormone (LH): Will be discussed in a later Chapter of the syllabus.

3. Growth Hormone (GH): Causes body cells to absorb amino acids and form protein for growth. The main function is to cause the elongation of bones.

4. Prolactin: stimulates milk formation by the breast after the birth of the baby.

5. Oxytocin: stimulates muscle contraction of uterus during birth, stimulates muscle contraction in the milk ducts during breast-feeding.

6. Antidiuretic Hormone (ADH): causes increased water reabsorption by kidneys.

7. Thyroid Stimulating Hormone (TSH): Combines with iodine at the thyroid gland to produce thyroxine.

Overproduction of GH causes gigantism and underproduction causes dwarfism.

The Hypothalamus

The hypothalamus links the nervous system with the endocrine system. It produces hormones that control the pituitary gland’s responses to messages from the brain and other hormones. Some these hormones, called releasing hormones, stimulate the pituitary gland to make other hormones. Others, called release inhibiting hormones, prevent the production of pituitary hormones.

An example is growth hormone releasing factor. This causes the production of growth hormone (GH) by the pituitary gland.

The Pineal Gland

This gland is in the brain. One hormone produced there is melatonin. Synthesis and release of melatonin is stimulated by darkness and inhibited by light. But even without visual cues, the level of melatonin in the blood rises and falls on a daily (circadian) cycle with peak levels occurring in the wee hours of the morning. Melatonin is readily available in drug stores and health food stores, and it has become quite popular. Ingesting even modest doses of melatonin raises the melatonin level in the blood to as much as 100 times greater than normal. These levels appear to promote going to sleep and thus help, insomnia to hasten recovery from jet lag, and to not to have dangerous side effects.

The Thyroid Gland

The thyroid gland produces the hormone called thyroxin. Thyroxin controls the rate of all the body’s internal reactions. In other words, thyroxin controls the rate of the body’s metabolism.

Physical conditions related to abnormal thyroid function are:

Hypothyroidism- Under Production of Thyroxine

1. Cretinism– Under production of thyroxin in young children. This results in low metabolic rates and results in retarded physical and mental development.

2. Myxoedema- Under production of thyroxin in adults. Characteristics are tiredness, lack of energy, slow mental and physical activity, and weight gain.

3. Goitre- Swelling of the thyroid caused by myxoedema.

Goitre

In cases of low production of thyroxine tablets are available to increase the thyroxine in the body. Since thyroxine needs iodine to be produced iodine is also administered to boost thyroxine levels.

Thyroxine Excess (Hyperthyroidism)

Thyroxine secretion is above normal. This causes a raised level of metabolism. Symptoms of over production of thyroxin are bulging eyes, weight loss heat production, nervousness, irritability, and anxiety. This condition is called Grave’s Disease. Corrective measures for Grave’s Disease are:

1. Drugs to suppress thyroid activity

2. Surgically remove part of the gland

3. Use radioactive iodine to destroy some of the gland.

The Parathyroids

parathyroids behind thyroid gland

There are 4 parathyroid glands. They are located within the thyroid gland. The hormone they produce is called parathormone. This hormone stimulates the release of calcium from the bones. That is why we must continue to include calcium in our diet even when our bones are fully grown.

The Thymus Gland

This gland is located behind the breastbone. It produces the hormone thymosin. This hormone causes white blood cells (lymphocytes) to become mature and active. These blood cells, as previously discussed in the Blood web page, are involved in the body’s immune system.

The Adrenal Glands

Click here to view an animation of the adrenal glands

Diagram showing the location of the adrenal glands

The adrenal glands are located on top of each kidney. They secrete the hormone called adrenaline (also called epinephrine). This hormone prepares the body for stress and is released when we are frightened or feel stress. It does the following:

1. Increases blood flow to the heart, muscles, and brain.

2. Reduces blood flow to the kidneys. This helps reduce blood loss if we are cut. It causes us to get pale.

3. Opens the bronchioles allowing us to get more air.

4. Increases glucose levels in the blood.

5. Increases heartbeat rate.

6. Increase muscular contraction and strength.

7. Increases mental alertness.

Pancreas

As discussed in the Human Nutrition web page the pancreas secretes pancreatic juice for the digestive system.

In addition, the pancreas produces the hormone called insulin. This hormone is produced in groups of cells called Islets of Langerhans. Insulin is needed because it reduces blood glucose levels in the blood. It causes cells, especially fat and muscle cells, to absorb glucose from the blood. The glucose is needed for cellular respiration or converted into glycogen. The glycogen is stored in the liver or the muscles for future use in cellular respiration.

Diabetes is a serious condition that results from 1 of 2 causes. In type 1 diabetes, the pancreas no longer makes insulin and therefore blood glucose cannot enter the cells to be used for energy. In type 2 diabetes, either the pancreas does not make enough insulin or the body is unable to use insulin correctly. Symptoms of diabetes are high glucose levels in the blood and urine, the production of large amounts of urine, severe thirst, loss of weight, and tiredness.

Injections of insulin, which are taken daily, the control of carbohydrate intake, exercise, and weight control treat diabetes.

Anabolic Steroids

Anabolic steroids are hormone supplements that habe been used. They build up muscle, speed up recovery of muscle from injury, and help strengthen bones. There are many serious side effects such as liver and adrenal gland failure, infertility, impotence, and the development of male characteristics in females that can result if they are misused. They are also, sometimes given to animals to promote increased lean muscle (meat) production. This practice is banned in the EU.

Control of Thyroxine Level

Control of thyroxine level as well as many other hormones is done by negative feedback. If the thyroxine level is normal the pituitary gland is inhibited from releasing thyroid stimulating hormone (TSH). As a result, no further thyroxine is produced. When thyroxine levels are low the pituitary gland produces TSH. This causes more thyroxine to be produced by the thyroid gland.

An Example of negative feedback in the role of the thyroid in maintaining body temperature at 37°C.:

The hypothalamus of the brain detects a drop in blood temperature.
The hypothalamus stimulates the pituitary to secrete TSH (thyroid-stimulating hormone).
This hormone stimulates the thyroid to increase its secretion of thyroxine.
The higher concentration of thyroxine increases metabolism and heat production increases.
The blood is warmed back to normal temperature.

OR:

Hypothalamus detecting raised blood temperature and reduces its stimulation of the pituitary.
High thyroxine levels inhibiting the release of TSH from the pituitary.
The increased level of thyroxine leads to the limitation or reduction of its secretion.
Body’s metabolism slows down as a result of less thyroxin. The body’s temperature goes down.

Review Chart of Major Hormonal Glands

Where the Hormone is Produced	Hormone(s) Secreted	Hormone Function
Adrenal Glands	Adrenalin	Causes Emergency Responses (fight/flight)
Pituitary Gland	Growth hormone	Affects growth and development; stimulates protein production
Pancreas	Insulin	Lowers blood sugar levels; stimulates metabolism of glucose, protein, and fat
Hypothalamus	Growth Hormone Releasing Factor	Causes growth hormone to be made
Pineal Gland	Melatonin	Controls body rhythms
Parathyroid Glands	Parathyroid hormone (Parathormone)	Affects bone formation and excretion of calcium and phosphorus
Thyroid	Thyroxine	Controls Metabolism
Thymus	Thymosin	Matures white blood cells

Eye Dissection

Cow Eye Dissection

Introduction:
How do we see? The eye processes the light through photoreceptors located in the eye that send signals to the brain and tells us what we are seeing. There are two types of photoreceptors, rods and cones. These photoreceptors are sensitive to the light. Rods are the most sensitive to light and therefore provide gray vision at night. Cones are mainly active in bright light and enable you to see color. There are 100 million rods compared to the 3 million cones located in your retina. The photoreceptors help you adjust to night and day. For example, if you walk inside from the sun, you can not initially see anything. This is due to the activity of the cones and the lack of activity of the rods. The rods become activated and adapted to the dim light, resulting in gray images formed in the dark. The same thing happens when you leave a dark movie theatre during the day. The rods are mainly activated and the cones have to adjust to sunlight when you leave the theatre.

Objective:
By dissecting the eye of a cow, which is similar to the eyes of all mammals including humans, you will gain an understanding of the structure and function of the parts of the eye.

Materials:
Cow eye, dissecting pan, dissecting kit, safety glasses, lab apron, and gloves

Procedure (External Structure):

Obtain a cow eye, place it in your dissecting pan, & rinse the eye with water.
Rotate the eye until the larger bulge or tear gland is on the top of the eye. The eye is now in the position it would be in a body as you face the body.
On the outside of the eye, locate the following parts:

fat– surrounds the eye & cushions it from shock
tear or lacrimal gland – forms a bulge on the top outer area of the eye & produces tears to wash the surface of the eye
tear ducts – tubes to carry the tears from the gland to the eye
optic nerve – a white cord on the back of the eye about 3mm thick just toward the nasal side; carries messages between the eye & brain
muscles – reddish, flat muscles found around the eye to raise, lower, & turn (right & left) the eye

Turn the eye so that it is facing you & examine these structures on the front surface of the eye:

eyelids – two moveable covers that protect the eye from dust, bright light, and impact
sclera – this is the tough, white outer coat of the eye that extends completely around the back & sides of the eye
cornea – a clear covering over the front of the eye that allows light to come into the eye (preservative often makes this appear cloudy)
iris – round black tissue through the cornea that controls the amount of light that enters the inner part of the eye (may be colored in humans)
pupil – the round opening in the center of the eye that allows light to enter and whose size is controlled by the iris

Click here for labeled eye model

Procedure (Internal Structure):

Place the eye in the dissecting pan so it is again facing you. Using your scalpel, pierce the white part of the eye or sclera just behind the edge of the cornea. Make a hole large enough for your scissors.
Using your scissors, carefully cut around the eye using the edge of the cornea as a guide. Lift the eye & turn it as needed to make the cut and be careful not to squeeze the liquid out of the eye.
After completing the cut, carefully remove the front of the eye and lay it in your dissecting pan.
Place the back part of the eye in the pan with the inner part facing upward.
Locate the following internal structures of the eye:

cornea – observe the tough tissue of the removed cornea; cut across the cornea with your scalpel to note its thickness
aqueous humor – fluid in front the eye that runs out when the eye is cut
iris – black tissue of the eye that contains curved muscle fibers
ciliary body – located on the back of the iris that has muscle fibers to change the shape of the lens
lens – can be seen through the pupil; use your scalpel & dissecting needle to carefully lift & work around the edges of the lens to remove it
vitreous humor – fluid inside the back cavity of the eye behind the lens
retina – tissue in the back of the eye where light is focused; connects to the optic nerve; use forceps to separate the retina from the back of the eye & see the dark layer below it

10. Answer the worksheet questions on the cow eye dissection.

Click here for eye dissection questions

Dispose of the eye as your teacher advises and rinse and return all equipment to the supply cart. Wash your hands thoroughly.

BACK

SEVEN PHYLA OF ALGAE

Sponges – A Coloring Worksheet

Review Chart of Major Hormonal Glands

Hypothalamus