What are distinguishing traits of animals? What are major characteristics of animal cells?
Animals are multicellular, heterotrophic (ingest their food), eukaryotes with tissues that develop
from embryonic layers; bodies held together by structural proteins (collagen), nervous tissues
and muscle tissues, most reproductive sexually (diploid stage being the dominating life cycle);
have hox genes
Major characteristics- Lack cell walls, no central vacuole, no chloroplasts, and have an
Distinguish tight junctions, gap junctions, desmosomes (anchoring) and tell the function
tight junctions- The plasma membrane of neighboring cells are very tightly pressed against
each other, bound together by specific proteins. Forming continuous seals around the cells, tight
junctions prevent leakage of extracellular fluid across a layer of epithelial cells. For example
tight junctions between skin cells make us watertight by preventing leakage between cells in our
gap junctions (communicating junctions)- provide cytoplasmic channels from one cell to an
adjacent cell and in this way are similar in their function to the plasmodesmata in plants. Gap
junctions consist of membrane proteins that surround a pore through which ions, sugars, amino
acids, and other small molecules may pass. Gap junctions are necessary for communication
between cells in many types of tissues, such as heart muscle, and in animal embryos.
desmosomes (anchoring junctions)- function like rivets, fastening cells together into strong
sheets. Intermediate filaments made of sturdy keratin proteins anchor desmosomes into the
cytoplasm. Desmosomes attach muscle cells to each other in a muscle. Some “muscle tears”
involve the rupture of desmosomes.
Describe some specializations (cell shape, which organelles abundant, cell-cell
junctions) found in these cells: a sperm, intestine transport epithelium, pancreatic
secretory epithelium, a macrophage, heart muscle.
Sperm- lots of mitochondria (need energy for movement) ~> get rid of all the extra stuff that
hinders fast movement like cytoplasm
Intestine transport epithelial - microvilli (for absorption), lysosomes, some have golgi, regular
supply of mitochondria
Pancreatic secretory epithelium - surface area important, rough ER, golgi
Macrophages - lysosomes, [strength, changeable, flexible]
Heart muscle -desmosomes, lots of mitochondria
Name the four major animal tissue types, tell how they differ from each other, and give
examples. Epithelial Tissue- Occurring as sheets of cells, epithelial tissues, or epithelia cover the outside
of the body and line organs and cavities within the body. They are closely packed often with tight
junctions and function as a barrier against mechanical injury, pathogens, and fluid loss. Epithelia
also form active interfaces with the environment are are polarized (two different sides). The
apical surface faces the lumen (cavity) or outside of the organ and is therefore exposed to fluid
or air. The opposite side of each epithelium is the basal surface. The basal surface is attached
to a basal lamina, a dense mat of extracellular matrix that separates the epithelium from the
Connective Tissue- Consisting of a sparse population of cells scattered through an
extracellular matrix, holds many tissues and organs together in place. The matrix generally
consists of a web of fibers embedded in a liquid, jellylike, or solid foundation. Within the matrix
are numerous cells called fibroblasts which secrete fiber proteins and macrophages.
Muscle Tissue- The tissue responsible for nearly all types of body movement. Consists of
filaments containing the proteins actions and myosin, which together enable muscles to
contract. There are three types of muscle tissue in the vertebrate body: skeletal, smooth, and
Nervous Tissue- Functions in the receipt, processing, and transmission of information. Nervous
tissue contains neurons, or nerve cells, which transmit nerve impulses and well as supports
cells called glial cells, or simply glia. In many animals, a concentration of nervous tissue forms a
brain, an information-processing center.
Tell how animal embryos are organized, and name the three embryonic germ layers.
Early Embryonic Development:
1. The zygote of an animal undergoes a series of mitotic cell divisions called cleavage.
2. An eight-cell embryo is formed by three rounds of cellular division.
3. In most animals, cleavage produces a multicellular stage called a blastula. The blastula is
typically a hollow ball of cells that surround a cavity called the blastocoel.
4. Most animals undergo gastrulation, a process in which one end of the embryo folds inward,
expands, and eventually fills the blastocoel, producing layers of embryonic tissues
5. The pouch formed by gastrulation, called the archenteron, opens to the outside via the
6. The endoderm of the archenteron develops into the tissue lining the animal’s digestive tract
3 embryonic germ layers: Ectoderm (outer layer), Mesoderm (middle layer), Endoderm (inner
Tell major evolutionary trends in the animal kingdom with respect to embryonic tissue
layers (2-3 tissue layers), gut (one opening or tube with mouth & anus), and body
symmetry (radial, bilateral). - Many radial animals are sessile (living attached to a substrate) or planktonic (drifting or weekly
swimming, such as jellyfish. Their symmetry equips them to meet the environment equally well
from all sides. In contrast bilateral animals typically move actively from place to place. Most
bilateral animals have a central nervous system that enables them to coordinate complex
movements (pg. 659).
What are hox genes? As more complex animals evolved, what happened to number of
All animals have Hox genes that regulate the development of body form from anterior to
posterior.. Although Hox genes have been highly conserved over the course of evolution, they
can produce a wide diversity of animal morphology. Hox genes increase with complexity.
What is the advantage of animals having a complete gut (with two openings rather than
It permits functional specialization -- different parts of the system may be specially adapted for
various functions of food digestion, nutrient absorption, and waste excretion. The complete digestive tube allows animals to continuously feed themselves without waiting for
residuals to be eliminated before beginning the digestion of new foods. In this way the
absorption of larger amount of nutrients is possible and therefore bigger and more complex
species can develop. Digestive tubes with two openings also make digestion more efficient
since they provide different sites with different physical and chemical conditions (mouth,
stomach, bowels) for the action of different complementary digestive enzymatic systems.
What is the function of internal skeletons, external skeletons, and hydrostatic skeletons?
Give an example of an animal with each. How is the skeleton related to muscle movement
● It shapes and supports the organism, protects inner organs, stores minerals, and helps
movement. Human skeleton is an example. Muscles on skeleton flex moving it allowing us to
● As the animal grows, it molts the old exoskeleton and secretes a new, larger one, a process called ecdysis.
Anthropods have an exoskeleton.
● found in soft-bodied animals consisting of a fluid-filled cavity surrounded by muscle, such as
jellyfish. The pressure of the fluid and action of the muscles are used to change an organism's
shape and produce movement.
Tell the advantage of each of these major evolutionary developments (derived traits)
within the vertebrates: jaws, lungs, tetrapod body form, amniotic egg.
● Allowed the animal to bite and tear their food.
● Allows vertebrate able to utilize gas exchange with oxygen in air and allowed to them to breath
Tetrapod Body Form
● Allowed vertebrates to walk on land with the pectoral and pelvic fins, changing to limbs with
digits. Gave them a way to move and chase pray.
● Key to Terrestrial life. Allowed the embryo to develop on land the dependence of tetrapods
reproducing in an aqueous environment. What animals were the immediate ancestors of birds, and to what class of vertebrates do
Theropods. Reptiles (dinosaurs). (If you’re curious, there is debate that birds evolved from
What is homeostasis? How does negative feedback help maintain homeostasis
Homeostasis- maintenance of internal balance (“steady state”) To achieve: animals maintain a
relatively constant internal environment even when the external environment changes
significantly (pg 860)
Negative feedback (a control mechanism) that reduces or “damps” the stimulus ... helps return
the body back to setpoint. (861 monitor/detector senses change > effector stimulates
sweat/blood vessels dilate > body cools down and returns to set point
Body temp falls below set point > monitor senses change > effector stimulates blood vessels to
constrict > body warms up back to set point
Negative feedback: response of body sweat that causes the initial change (body temp increase)
to return back to the set point
Define: hormone, endocrine gland, neurosecretory cell, tropic hormone ( = “tropin”)
Hormone- a chemical released by a cell, a gland, or an organ that sends out messages that
affect cells in other parts of the organism Endocrine Gland- a gland that secretes hormones into the surrounding fluid of blood rather
than a duct to reach target cells
Neurosecretory Cell- neurons that secrete molecules a very short distance across a synapse
to target cells, such as other neurons and muscle cells.
Tropic Hormone- hormones that regulate the function of other endocrine cells or glands.
How do peptide (water-soluble) & steroid (lipid-soluble) hormones differ in action on
Peptide (water-soluble) hormones bind to plasma membrane receptors, generating a chemical
signal while steroid (lipid-soluble) hormones pass through the plasma membrane and bind to
receptors once inside the cell
Use insulin to explain homeostasis of blood glucose, including regulation by negative
Negative feedback (reduction of increased blood sugar):
Increase in blood sugar levels > change in level is detected > pancreas (beta cells) stimulated to
produce insulin > insulin is released and reduces blood sugar levels > blood sugar returns to set
Decrease in blood sugar levels > change in level is detected > pancreas (alpha cells) stimulated
to release glucagon > liver breaks down glycogen and releases it into the blood > blood sugars
rise to acceptable levels
Explain how type I and type II diabetes mellitus differ in cause and how each can be
Type I diabetes: body does not produce insulin to regulate levels of blood sugar, therefore
insulin injections may be used as treatment
Type II diabetes: blood sugar levels are high and there is an insufficient response of increased
blood sugar: body does not produce enough insulin, or does not respond to the hormone; this is
controlled by a change in diet (low sugar foods)
(application problem) One cause of juvenile-onset diabetes is an autoimmune attack of
the beta cells of pancreas. Which type of diabetes would result?
Type I diabetes is characterized by the inability to create insulin.
Draw a homeostatic feedback diagram involving thyroxine, TSH (thyroid-stimulating
hormone) and TRH (a TSH-releasing hormone). Indicate what stimulates what, also indicate two possible negative feedback loops.
Why can a hyperactive thyroid (high thyroxine) lead to a slightly elevated body
temperature? (application problem) Patient A is found to have a deficiency of dietary
iodine. Explain how this dietary deficiency could lead to goiter (enlarged thyroid gland).
(page 988): Without sufficient iodine, the thyroid gland cannot synthesize adequate amounts of
T3 and T4, and the resulting low blood levels of T3 and T4 cannot exert the usual negative
feedback on the hypothalamus and anterior pituitary. As a consequence, the pituitary continues
to secrete TSH. and elevated TSH levels cause the enlargement of the thyroid gland resulting in
Compare and contrast the adrenal medulla and the adrenal cortex (how each gland is
stimulated, their hormone products, relative speed and duration of response) in the
body's stress response. (990) Adrenal glands -- associated with the kidneys
Adrenal Medulla- produces hormones i.e. epinephrine/norepinephrine, [simple neurohormone
pathway] triggers signal transduction//derive from neural tissue during embryonic
development//epinephrine--stronger effect on heart and metabolic rates norepinephrine--
modulating blood pressure
***Nerve signals carried from the brain via involuntary (autonomic) neurons regulate secretion
by the adrenal medulla. In response to a stressful stimulus, nerve impulses travel to the adrenal
medulla, where they trigger the release of catecholamines from neurosecretory cells.
Adrenal Cortex- produces steroids, glucocorticoids, mineralocorticoids// Consists of true
Peptide hormones respond faster because they bind to receptors on the surface of the cell.
Steroids have a longer response and bind to transcription factors within the cell.
How can the same hormone - e.g., epinephrine - affect different target organs in different
Different target organs have different receptors and different signal transduction pathways in
response to the hormone.
(application problem, later) When neurons in the brain's hypothalamus detect an
increase in blood solute concentration, the pituitary secretes antidiuretic hormone
(ADH). (ADH in blood circulation causes the transport epithelium in the kidney excretory
tubules to be more permeable to water; as a result more water is reabsorbed back into
the blood and the urine produced is more concentrated.) Explain how ADH thus helps
maintain homeostasis of solute-water in the blood. Alcohol inhibits ADH secretion—what
ADH allows water to re-enter blood, so to maintain homeostasis to the increased blood solute,
the increase of water counteracts the increased solute concentration (i.e. larger volume to
solute concentration = equilibrated blood solute concentration). ADH transports the water that
would be excreted in urine and redirects it back into the blood to balance out blood solute
The inhibition of ADH caused by alcohol would result in dehydration, because the increase of
blood solute would not experience negative feedback (to return to homeostasis).
Name two endocrine systems that are regulated by the hypothalamus and two hormone
systems that are regulated with no input from the hypothalamus.
2 endocrine systems regulated by the hypothalamus- pituitary [ACTH affects adrenal cortex],
thyroid, adrenal cortex Not regulated by hypothalamus- Pancreas [glucose regulation.. insulin & glucagon... not
receiving signalings from hypothalamus], adrenal medulla