Bio 1220- Final exam (complete coverage)

What is a gamete?

A specialized sex cell carrying 23 chromosomes (haploid).

What is the central regulator of endocrine function in reproduction?

The hypothalamus-pituitary unit.

Which hormone is released by the hypothalamus to start the reproductive axis?

Gonadotropin-releasing hormone (GnRH).

What two hormones are released by the pituitary gland in response to GnRH?

Luteinizing hormone (LH) and follicle stimulating hormone (FSH).

Where does sperm development take place?

In the seminiferous tubules within the testes.

What is the function of Sertoli cells?

They act as support cells for developing sperm and have receptors for FSH.

What is the function of Leydig cells?

They have LH receptors and produce testosterone to stimulate sperm production.

Where is mature sperm stored?

In the epididymis.

Which accessory gland provides fructose as an energy source for sperm?

Seminal Vesicles (contributing ~60% of semen volume).

What is the role of the Prostate Gland’s fluid?

It provides an alkaline fluid to offset the acidity of the female reproductive tract.

Which gland releases a lubricating fluid that cleans urine residue from the urethra?

Bulbourethral Glands.

What gas is released to trigger a penile erection?

Nitric oxide, which relaxes smooth muscles and dilates arteries.

What are the two main phases of the Ovarian Cycle?

The Follicular Phase (days 1-14) and the Luteal Phase (days 15-28).

What occurs during the Follicular Phase?

Egg development, moving from a primordial follicle to a vesicular follicle.

What is the "antrum" in a vesicular follicle?

A fluid-filled cavity that develops when there are 6-7 layers of granulosa cells.

What hormone spike triggers ovulation?

A high level of Luteinizing hormone (LH).

What structure does the ruptured follicle become after ovulation?

The corpus luteum.

What hormone does the corpus luteum primarily produce?

Progesterone.

What are the three phases of the Uterine (menstrual) cycle?

Menstrual Phase (1-5), Proliferative Phase (6-14), and Secretory Phase (15-28).

What is sperm capacitation?

Functional and morphological changes in sperm (e.g., faster tail beating) to prepare for fertilization.

What is the "block to polyspermy"?

The cortical reaction that destroys sperm receptors and hardens the area around the egg to prevent more than one sperm from entering.

Where does fertilization typically occur?

In the Fallopian tube.

What is the difference between dizygotic and monozygotic twins?

Dizygotic are fraternal (two eggs fertilized); monozygotic are identical (one zygote splits).

At what stage does the embryo implant into the uterine wall?

The blastocyst stage.

What part of the blastocyst embeds into the uterine wall?

The trophoblast cells.

Why can a pregnancy test give a positive result shortly after implantation?

Because trophoblast cells secrete a hormone (hCG) detectable in urine.

What is the primary characteristic of an endocrine gland?

They are ductless glands that secrete hormones directly into surrounding interstitial fluid and blood.

What are the two chemical classifications of hormones?

Amino acid-based (variable size) and Steroids (synthesized from cholesterol).

Which hormones are lipid-soluble and can pass through the plasma membrane?

Steroids.

What is the function of a "second messenger"?

It is used by water-soluble (amino acid-based) hormones to initiate a cellular response since they cannot enter the cell.

What are the three types of stimuli that trigger hormone release?

Humoral (blood levels), Neural (nerve fibers), and Hormonal (other hormones).

Which gland is known as the "master gland" and has two distinct lobes?

The Pituitary gland (Hypophysis).

What are the two lobes of the pituitary gland called?

The Anterior Pituitary (adenohypophysis) and the Posterior Pituitary (neurohypophysis).

What hormone stimulates the thyroid gland to release thyroxine?

Thyroid-stimulating hormone (TSH).

What are the two hormones stored and released by the posterior pituitary?

Oxytocin and Antidiuretic Hormone (ADH).

What is the primary role of Oxytocin?

Stimulating uterine contractions during childbirth and milk release during breastfeeding.

What does Antidiuretic Hormone (ADH) target and what is its effect?

It targets kidney tubules to inhibit urine formation and prevent dehydration.

How does the hypothalamus control the anterior pituitary?

By secreting "releasing hormones."

What are the two distinct parts of the adrenal glands?

The Adrenal Medulla (inner) and the Adrenal Cortex (outer).

What does the Adrenal Medulla secrete?

Epinephrine and norepinephrine (in a 4:1 ratio).

Which corticosteroid is essential for regulating sodium and potassium concentrations?

Aldosterone (a mineralocorticoid).

What is the primary role of Cortisol?

It is a glucocorticoid that helps keep blood glucose levels constant between meals.

Where is the thyroid gland located?

In the anterior neck, on the trachea just inferior to the larynx.

What is the largest purely endocrine gland in the body?

The Thyroid gland.

Which hormone is the body's major metabolic hormone?

Thyroid hormone (TH).

What is the function of the Parathyroid glands?

They produce Parathyroid Hormone (PTH) to control calcium balance in the blood.

What are the two main endocrine hormones of the pancreas?

Glucagon (increases blood glucose) and Insulin (decreases blood glucose).

What is the difference between Type I and Type II Diabetes?

Type I is a lack of insulin production; Type II is resistance to insulin or insufficient production.

Which gland secretes melatonin?

The Pineal gland.

What happens to the size of the thymus after puberty?

It decreases in size (atrophies).

Which organ is a temporary endocrine organ that influences pregnancy?

The placenta.

What are the primary endocrine products of the ovaries?

Estradiol and progesterone.

What are the primary endocrine products of the testes?

Testosterone.

What is an example of a hormone produced by the gastrointestinal tract?

Gastrin or Secretin.

What are the three categories of muscle?

Skeletal, cardiac, and smooth.

Which muscle type is long, cylindrical, multinucleated, and voluntary?

Skeletal muscle.

What defines "striated" muscle at the protein level?

Actin and myosin proteins are arranged very regularly within the fibers.

What is the basic unit of muscle contraction?

The sarcomere.

What structure acts as the border of a sarcomere and creates striations?

Z lines.

In a sarcomere, why are A bands dark?

Because myosin is thick.

What neurotransmitter is released into the synaptic cleft to trigger skeletal muscle contraction?

Acetylcholine (ACh).

What structure carries the electrical signal to the interior of a muscle fiber?

T-tubules.

The release of which ion from the sarcoplasmic reticulum initiates contraction?

Calcium (Ca2+).

Which two proteins are bound to actin and regulate its interaction with myosin?

Tropomyosin and troponin.

What is the "power stroke" in muscle contraction?

The bending of the myosin head toward the center of the sarcomere, pulling actin along.

What is required for the myosin head to detach from actin after a power stroke?

One molecule of ATP.

What causes rigor mortis after death?

ATP synthesis stops, so myosin cannot detach from actin, leaving muscles stiff.

What is a motor unit?

One neuron and all the muscle fibers it connects to.

What are the three phases of a muscle twitch?

Latent period, contraction, and relaxation.

How does increasing the frequency of stimulation affect muscle tension?

It increases tension by allowing more calcium, more myosin binding sites, and more cross-bridges.

What is physiological tetanus?

A state where high-frequency signals cause muscle relaxation to disappear.

How does the strength of stimulation affect muscle recruitment?

Smallest fibers are stimulated first; larger fibers are added as more force is needed.

What determines the velocity of a muscle contraction?

How quickly cross-bridges recycle, which is limited by the rate of ATP synthesis.

What are the characteristics of oxidative fibers?

Rich in mitochondria, lots of capillaries, contain red myoglobin, and produce ATP efficiently.

What are the characteristics of glycolytic fibers?

High glycolytic enzymes, few mitochondria, larger diameter, and no myoglobin.

Which fiber type is best for maintaining posture or running a marathon?

Slow oxidative (SO) fibers. ( fast oxidative would also be good for a marathon ).

Which fiber type is used for rapid, intense movements like weight lifting?

Fast Glycolytic (FG) fibers.

What structure allows cardiac muscle cells to behave as a single functional unit?

Gap junctions (intercalated discs).

Where is smooth muscle typically found?

In the walls of blood vessels, the digestive tract, and the uterus.

Does smooth muscle contain sarcomeres?

No, but it does contain actin and myosin in an arrangement that permits more stretching.

What is the difference between single-unit and multi-unit smooth muscle?

Single-unit cells contract as a synchronized unit; multi-unit cells contract independently for precise control.

Isotonic?

Muscle shortens.

Isometric?

Muscle does not shorten but force is created.

What are the two main components that make up blood as a connective tissue?

Cellular elements (formed elements) and an extracellular matrix (plasma).

What percentage of plasma is typically composed of water?

Approximately 92%.

What is the most abundant plasma protein, and what is its primary function?

Albumin; it is manufactured by the liver and serves as a binding protein for transporting fatty acids and steroid hormones.

Which plasma proteins are known as antibodies and are involved in immunity?

Gamma globulins (immunoglobulins).

What is the primary function of erythrocytes (red blood cells)?

To transport oxygen and some carbon dioxide between the lungs and tissues.

What is the lifespan of a typical red blood cell?

Approximately 120 days.

What iron-rich protein in RBCs is responsible for oxygen transport?

Hemoglobin (Hb).

Which hormone, released by the kidneys and liver, triggers RBC production in bone marrow?

Erythropoietin.

In which organ is blood cells stored and old RBCs removed from circulation?

In the spleen.

What is the term for the percentage of red blood cells in a blood sample?

Hematocrit.

What are the two major groups of leukocytes (white blood cells)?

Granular leukocytes and agranular leukocytes.

Which leukocyte is the most common?

Neutrophils.

What are the three major groups of granular lymphocytes?

Neutrophils, Eosinophils, Basophils.

What are the three major groups of agranular lymphocytes?

Natural killer (NK) cells, B cells, and T cells.

What are platelets fragments of, and where are they formed?

They are fragments of megakaryocytes formed in the red bone marrow.

What are the four blood types in the ABO system?

Type A, type B, type AB, and type O.

Why is blood type O considered the "universal donor"?

Because it lacks A and B antigens, so any recipient antibodies have nothing to attach to.