biology 22 hand-out (scope of second lab exam) · pdf filebiology 22 hand-out (scope of second...

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Bio22 Handout/1stSem2016-2017/NECRamirez (Taken from the PowerPoint Presentations of Mr. Jeremy G. Vicencio, DB-CAS)

BIOLOGY 22 HAND-OUT (Scope of Second Lab Exam)

Exercise 7: Integuments

Invertebrate Integument

Amoeba Plasmalemma

Paramecium Pellicle

Sponge (Grantia) Pinacoderm and Choanoderm

Hydra Epidermis and Gastrodermis

Planarian (Dugesia) Ciliated ventral epidermis, dorsal epidermis with rhabdites

Trematode (Fasciola) Syncytial tegument

Nematode (Ascaris) Non-chitinized cuticle and epidermis

Annelid (Lumbricus) Non-chitinized cuticle, epidermis, and dermis

Arthropod (Cockroach) Chitinized cuticle and epidermis

Echinoderm (Starfish) Epidermis and dermis (with embedded ossicles and/or spines composed of calcium

carbonate)

Sponge (Grantia sp.)

Cnidarian (Hydra sp.)

Planarian (Dugesia sp.)

• Pinacoderm – outer layer of cells (pinacocytes),

simple squamous epithelium

• Mesohyl – middle layer of connective tissue,

sponge wall

• Choanoderm – inner layer of flagellated collar

cells (choanocytes)

A Epidermis

B Mesoglea

C Gastrodermis

D Coelenteron

(Gastrovascular cavity)

• The body is covered by a monolayered,

secretory epidermis

• The ventral, but not the dorsal, surface is

ciliated

• An underlying basal lamina is distinct

• The epidermis contains numerous secretory

vesicles and rod-shaped, membrane-enclosed

secretions (rhabdites)

• When expelled at the surface, rhabdites

absorb water and expand to become sticky

mucus which assists in trapping prey

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Trematode (Fasciola sp.)

Nematode (Ascaris sp.)

Annelid (Earthworm: Lumbricus sp.)

Insect (Cockroach)

• Syncytial, noncuticularized epidermis

• Syncytium – a multinucleated mass of cytoplasm that is not separated into individual

cells (occurs when a cell divides without cytokinesis)

• The tegument is armed with various penetration glands as well as organs for adhesion

such as suckers, hooks, and spines

• The body is covered by a thick extracellular cuticle

(heavy, transparent layer)

• The cuticle is secreted by the epidermis (thin, pale, pink

layer that may be separated from the cuticle by a white

space)

• In the absence of circular muscles, the cuticle plays an

important role in containing the hydrostatic pressure of

the hemocoel

• The outermost layer is the thin, tough, iridescent cuticle

composed of collagen fibers secreted by the epidermis

beneath it

• The epidermis is composed of simple columnar epithelium

containing a number of sensory and secretory cells

• A dermis composed of connective tissue lies beneath the

epidermis

• The epidermis secretes a complex cuticular exoskeleton

which must undergo ecdysis (molting) to permit

increase in size

• The cuticle is a thin, non-cellular material

• Epicuticle – non-chitinized, highly resistant to water and

other solvents

• Endocuticle – extremely tough and flexible due to cross-

linking of protein and chitin fibers in a laminated pattern

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Echinoderm (Starfish)

Vertebrate (Frog)

Vertebrate (Human)

• Ossicles – calacareous (composed of calcium carbonate)

plates that forms the endoskeleton

• Spines and granules are external expressions of the

endoskeleton and are also composed of calcium carbonate

• The integument of echinoderms are particularly important

for defense or protection

2 Dermal ossicles

5 Spines

• Epidermis is subdivided into stratum corneum and

stratum germinativum

• Dermis is subdivided into stratum spongiosum and

stratum compactum

• Poison glands – produce substances that may range

from mildly irritating to very toxic; the epithelium

is simple squamous

• Mucus glands – produce mucus to maintain the

skin’s moisture and permeability for gas exchange;

the epithelium is cuboidal

• Both poison and mucus glands arise as

invaginations of the epidermis which migrate down

to the dermis

• Chromatophores – produce pigment that is absorbed

by the neighboring epithelial cells

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Layer Description/Function

Epidermis Surface layer of the skin covering and protecting the dermis; it contains proteins that

make the skin impermeable and block UV rays

Stratum Corneum Layer of the epidermis consisting of dead cells rich in keratin (the protein that protects

the skin); it is shed as a new layer is formed.

Stratum Lucidum Layer of the epidermis usually present only in the thick skin of the palms of the hands

and soles of the feet.

Stratum Granulosum Layer of the epidermis whose cells help to form keratin, which renders the skin

impermeable.

Stratum Spinosum Layer of the epidermis consisting of cells from the stratum basale, which continue to

divide to form the stratum granulosum.

Stratum Basale Layer of the epidermis whose cells divide and migrate toward the surface to form the

upper layers, thus ensuring renewal of the epidermis.

Dermis Layer of skin enclosing tactile receptors ensuring nutrition and support of the epidermis

Papillary dermis Uppermost layer of the dermis composed of fine and loosely arranged collagen fibers.

Reticular dermis Lower layer of the dermis composed of thick, densely packed collagen fibers, and the

primary location of dermal elastic fibers.

Subcutaneous tissue Tissue rich in veins and nerves at the base of the dermis enabling especially the

absorption of shocks.

Eccrine sweat gland Sweat-secreting organ whose excretory duct opens onto the surface of the skin; the

sweat glands help especially in the elimination of waste.

Sudoriferous duct Duct carrying sweat produced by the sweat gland to the surface of the skin.

Apocrine sweat gland Sweat-secreting organ whose excretory duct opens into the hair follicle.

Sebaceous gland Organ connected to a hair follicle secreting a fatty substance (sebum) that lubricates the

hair and skin, making them impermeable to air and water.

Pore Orifice in which the sweat duct opens, allowing excretion of sweat onto the surface of

the skin.

Hair Threadlike epidermal outgrowth present on almost the entire body having a sebaceous

gland and an arrector pili muscle; it plays a protective role.

Arrector pili muscle Muscle attached to a hair follicle and whose contraction raises the hair on end as a result

of cold or fear.

Hair follicle Small cavity of the dermis and hypodermis in which the hair root is implanted and which

receives secretions from the sebaceous and sweat glands.

Hair bulb Enlarged terminal part of the follicle from which hair develops and whose base receives

the papilla.

Exercise 8: External Anatomy of the Frog

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Exercise 9: Skeletal System

*Refer to the lab manual for the list of parts of the frog skeletal system

Types of Skeletal System:

• Support for the animal body

• Terrestrial environment – prevents the animal’s body from collapsing under its own weight.

• Aquatic environment – supports the shape of the animal’s body to counteract the pressure that acts on it.

Bone always arises by the replacement of some pre-existing tissue

• If the pre-existing tissue is hyaline cartilage, the process is called endochondral ossification (long bones)

• If the pre-existing material is embryonic mesenchyme, the process is called intramembranous ossification

(flat bones of the skull)

Examples of Cartilage Bones and Dermal Bones

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Exercise 10: Muscular System

*Refer to the lab manual for the list of parts and action of the muscles

Muscle Function

Extensor Straightens a joint

Flexor Bends a joint

Abductor Moves a body part away from the midline of the body

Adductor Moves a body part toward the midline of the body

Levator Raises a body part

Depressor Lowers a body part

Protractor Causes a body part to be thrust forward or outward

Rotator Rotates a body part

Exercise 11: Muscle Physiology

Muscle twitch - the response of the muscle to a single brief threshold stimulus

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Phases of a Muscle Twitch

1. Latent Period

the sarcolemma and the T tubules depolarize

calcium ions are released into the cytosol

cross bridges begin to cycle but there is no visible shortening of the muscle

2. Contraction

myosin cross bridge cycling causes sarcomeres to shorten

3. Relaxation

calcium ions are actively transported back into terminal cisternae

cross bridge cycling decreases and ends

muscle returns to its original length

Muscle Response to Increased Frequency of Stimulation: Wave Summation

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Summation - if two stimuli are delivered in rapid succession, the second twitch will be greater than the first; this only

occurs if repolarization is not complete.

Tetanus - a state of continuous muscular contraction, especially when induced artificially by rapidly repeated stimuli

Incomplete tetanus - there is still evidence of partial relaxation or reduction in measured tension

Complete tetanus - there is no evidence of partial relaxation or reduction in measured tension

Fatigue - inability of the muscle to respond to stimulation

Caused by:

a build-up of acidic compounds which affect protein functioning

a relative but not total lack of ATP

and ionic imbalances resulting from membrane activities

Treppe (Staircase Effect) - a phenomenon in muscle tissue in which a number of stimuli of the same strength are

applied to the muscle after a period of rest in the relaxed state, the first few contractions of the series show a

successive increase in amplitude (strength)

the increase in efficiency is due to local temperature increase, increased enzyme efficiency, increased calcium

ion availability and some increase in structural elasticity

“the warm-up effect"

Stimuli

• Subthreshold stimulus: A stimulus which does not evoke a visible response. The number of motor units

responding is not sufficient to cause visible movement.

• Threshold: The minimum stimulus which can evoke a response.

• Recruitment: A stronger response than threshold because additional motor units join in to generate an

increase in tension.

• Maximal stimulus: When all motor units are being recruited and more intense stimulus does not evoke

greater tension.

Length-Tension relationship

The strength of a muscle contraction can be altered by

changing the starting length of a muscle.

Unstretched Muscle

• The overlapping thin filaments from opposite ends of the sarcomere, interfere

and conflict with each other.

• This restricts productive cross bridge building and less tension develops. The

unstretched muscle produces a relatively weak contraction.

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Moderately Stretched Muscle

• Maximum tension is developed when there is an optimum overlap of thin and

thick filaments so that all cross bridges can participate in the contraction.

Overstretched Muscle

• The thin filaments are pulled almost to the ends of the thick filaments where

little tension can be developed.

Isotonic vs. Isometric Contractions

• Isotonic – tension rises and the skeletal muscle’s length changes.

• lifting an object off the desk, walking, running

• Isometric – the muscle as a whole does not change length, and the tension produced never exceeds the resistance

• holding a heavy weight above the ground, pushing against a locked door, trying to pick up a car

Exercise 12: Nervous System

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Central Nervous System Parts and Functions

Part Functions

Cerebrum Movement, sensory processing, olfaction, language and communication, learning and

memory

Thalamus Relays sensations, special sense and motor signals to the cerebral cortex, regulates

consciousness, sleep, and alertness

Hypothalamus Links the nervous system to the endocrine system via the pituitary gland (hypophysis);

synthesizes and secretes neurohormones; secretes ADH and oxytocin; controls body

temperature, hunger, thirst, sexual desire, fatigue, and circadian cycles

Optic lobes Integrates visual information with other sensory inputs; relays auditory information

Midbrain nuclei Involuntary control of muscle tone; processing of incoming sensations and outgoing motor

commands

Cerebellum Important in motor control (coordination, precision, and timing); involved in cognitive

functions, as well as emotional functions such as regulating fear and pleasure responses;

control of outgoing movements for equilibrium, muscle tone, posture

Pons The pons contains nuclei that relay signals from the cerebrum to the cerebellum, along with

nuclei that deal primarily with sleep, respiration, swallowing, bladder control, hearing,

equilibrium, taste, eye movement, facial expressions, facial sensation, and posture

Medulla Oblongata The medulla contains the cardiac, respiratory, vomiting and vasomotor centers and deals

with autonomic functions, such as breathing, heart rate and blood pressure.

Spinal Cord The spinal cord has three major functions:

1) Serve as a conduit for motor information, which travels down the spinal cord; 2) Serve

as a conduit for sensory information, which travels up the spinal cord and 3) Serve as a

center for coordinating certain reflexes.

Development of the Nervous System

Early Development Late Development Maturity

Forebrain (prosencephalon) Telencephalon Cerebrum

Diencephalon Thalamus

Hypothalamus

Midbrain (mesencephalon) Mesencephalon Optic lobes

Midbrain nuclei

Hindbrain (rhombencephalon) Metencephalon Cerebellum

Pons

Myelencephalon Medulla Oblongata

Cranial Nerves of the Frog

Number Name Nature Function

I Olfactory Purely Sensory Transmits the sense of smell

II Optic Purely Sensory Transmits visual information

III Oculomotor Mainly Motor Movement of eye muscles

IV Trochlear Mainly Motor Movement of eye muslces

V Trigeminal Sensory and Motor Muscles of mastication, conveys sensation

VI Abducens Mainly Motor Movement of eye muscles

VII Facial Sensory and Motor Movement of facial muscles, chewing,

movement of neck

VIII Auditory Mostly Sensory Hearing and sense of equilibrium

IX Glossopharyngeal Sensory and Motor Taste and touch, movement in the pharynx

X Vagus Sensory and Motor Taste, controls muscles for voice and resonance

and the soft palate

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Spinal Nerves of the Frog

Number Function

I Forms brachial plexus that controls motor reflex of upper body

II

III

IV Supply the musculature and the skin of abdomen

V

VI

VII Unite to form the sciatic plexus which results in the sciatic nerve of the hind leg

VIII

IX

X Supplies the cloaca, urinary bladder, and oviducts

Plexus - an area where the nerves branch and rejoin

• Brachial plexus

– An arrangement of nerve fibers that run from the spine and proceed through the neck, the axilla

(armpit region), and into the arm

– Responsible for cutaneous and muscular innervation of the upper limb

– Lesions can lead to severe functional impairment

• Sacral plexus

– Part of the lumbosacral plexus and emerges from the sacral vertebrae

– Provides motor and sensory nerves for the posterior thigh, most of the lower leg, the entire foot, and

part of the pelvis

Meninges - continuous sheets of connective tissue that cover the brain and spinal cord

From outside in, these are the:

• Dura mater – pressed against the bony surface of the interior of the vertebrae and the cranium

• Arachnoid mater – so named because of its spider web-like appearance, covered by a sheet of flat cells

thought to be impermeable to fluid

• Pia mater – very delicate membrane which firmly adheres to the surface of the brain and spinal cord, also

covered by a sheet of flat cells thought to be impermeable to fluid; pierced by blood vessels which travel to

the brain and spinal cord, and its capillaries are responsible for nourishing the brain

Cerebro-spinal fluid - a cushion between the arachnoid mater and pia mater, produced by the choroid plexus

• Buoyancy: allows the brain to maintain its density without being impaired by its own weight, which would cut

off blood supply and kill neurons in the lower sections without CSF

• Protection: protects the brain tissue from injury when jolted or hit

• Chemical stability: rinsing of metabolic waste from the CNS allows for homeostatic regulation of the

distribution of neuroendocrine factors, to which slight changes can cause problems or damage to the nervous

system

• Prevention of brain ischemia: decreasing the amount of CSF in the limited space inside the skull decreases

total intracranial pressure and facilitates blood flow

White matter vs. Gray Matter

• Both the spinal cord and brain consist of

– White matter: bundles of axons each coated with a sheath of myelin

– Gray matter: masses of cell bodies and dendrites – each covered

with synapses

• The spinal cord is arranged with white matter on the outside and gray

matter in the center

• In the brain of mammals, this pattern is reversed. However, the brains

of lower vertebrates like fishes and amphibians have their white matter

on the outside of their brain as well as their spinal cord

Exercise 13: Nervous Responses

(Refer to your Oral Reports/PowerPoint presentations, which are sufficient.)

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