MCAT Biology/biochemistry review || very Flawless.
Hypothalamus function correct answers The bridge between the nervous system and the
endocrine system. This is because it regulates the pituitary gland
It is regulated by negative feedback
and helps with homeostasis
Steroid Hormones: bloodstream travel correct answers Not water soluble and thus must be
carried by proteins in the bloodstream to be able to travel around the body
Peptide hormones: bloodstream travel correct answers Water soluble so they travel freely in the
bloodstream and do not require carriers
Steroid Hormones: effects correct answers Slower but longer lived then peptides
this is because steroid hormones cause alterations in the amount of mRNA and protein present in
a cell by direct action of DNA
Steroid Hormones: How they work correct answers They cross the cell membrane receptors are
intracellular
When binding to receptor complexes undergo conformational changes
the receptor then binds directly to DNA
Peptide Hormones: effects correct answers Usually rapid but short lived because they act through
secondary messengers
It is quicker to turn them on and off when compared with steroid hormones
Peptide hormones: How they work correct answers Bind to the outside of the cell considered first
messengers
triggers second signal known as secondary messenger
causes signal cascade which causes amplification
Common Secondary messengers correct answers cAMP, IP3, Calcium, Inosital
Monosynaptic reflex vs polysynaptic reflex correct answers Mono: a reflex arc in an animal
consisting of only one sensory neuron and one motor neuron
poly: one or more interneurons connect afferent (sensory) and efferent (motor) signals
What is the neurotransmitter responsible for the parasympathetic response in the body? correct
answers Acetylcholine
Main role of parasympathetic nervous system correct answers to conserve energy
afferent vs efferent neurons correct answers Afferent neurons are sensory neurons that carry
nerve impulses from sensory stimuli towards the central nervous system and brain, while efferent
neurons are motor neurons that carry neural impulses away from the central nervous systme and
towards muscles to cause movement.
,Thymosin; source, type, and action? correct answers 1. Source = thymus.
2. Peptide hormone.
3. Action = stimulates T-cell development.
Atrial naturetic peptide ANP; source, type, and action? correct answers 1. Source = Heart (Atria)
2. Peptide hormone
3.Promotes salt and water excretion
Erythropoietin; source, type, and action? correct answers 1. Source = Kidney.
2. Peptide hormone.
3. Action = stimulates bone marrow to produce erythrocytes.
Melatonin; source, type, and action? correct answers 1. Source = Pineal gland.
2. Peptide hormone.
3. Action = involved in circadian rhythm.
Progesterone; source, type, and action? correct answers 1. Source: Ovary (and placenta)
2. Type: Steroid
3. Action: Promotes maintenance of the endometrium
Estrogen; source, type, and action? correct answers 1. Source = ovary and placenta.
2. Steroid.
3. Action = develop and maintains female reproductive system and female secondary sex
characteristics.
testosterone; source, type, and action? correct answers 1. Source = testis and adrenal cortex.
2. Steroid.
3. Action = develops and maintains male reproductive system and male secondary sex
characteristics.
Somatostatin; source, type, and action? correct answers 1. Source = pancreas, delta-cells.
2. peptide hormone.
3. Action = suppresses secretion of glucagon and insulin.
Insulin; source, type, and action? correct answers 1. Source = pancreas, beta-cells.
2. Peptide hormone.
3. Action = lowers blood glucose concentrations and increases anabolic processes.
Glucagon; source, type, and action? correct answers 1. Source = pancreas, alpha cells.
2. Peptide hormone.
3. Action = stimulates glycogen breakdown [glycogenolysis]; increase blood glucose
concentrations.
Epinephrine + Norepinephrine; source, type, and action? correct answers 1. Source = Adrenal
medulla
, 2. Amino Acid-derivative
3. Increases blood glucose & heart rate; dilate bronchi; alter blood flow patterns (adrenaline)
Aldosterone (mineralocorticoids); source, type, and action? correct answers 1. Adrenal Cortex
2. Steroid
3. Increases water reabsorption in kidneys by increasing sodium reabsorption: promote
potassium and hydrogen ion excretion
Parathyroid (PTH); source, type, and action? correct answers 1. Parathyroids
2. Peptide hormone
3 Increases blood calcium concentrations
Glucocorticoids (cortisol & cortisone) ; source, type, and action? correct answers 1. Adrenal
Cortex
2. Steroid
3. Increases blood glucose concentration decreases protein synthesis; anti inflammatory
Calcitonin; source, type, and action? correct answers 1. Source = thyroid parathyroid cells or c-
cells.
2. Peptide hormone.
3. Action = decreases blood calcium concentrations.
T3 & T4; source, type, and action? correct answers 1. Source = thyroid (follicle cells)
2. Amino Acid-derivative
3. Stimulates metabolic activity
Oxytocin; source, type, and action? correct answers 1. Source: Hypothalamus (released by
posterior pituitary)
2. Type: Peptide
3. Action: Stimulates uterine contractions during labor and milk secretion during lactation; may
promote bonding behavior
ADH; Vasopressin; source, type, and action? correct answers 1. Hypothalamus: posterior
pituitary
2. Peptide Hormone
3 Stimulates water reabsorption in kidneys by increasing permeability of collecting duct
Growth Hormones; source, type, and action? correct answers 1. Anterior Pituitary
2. Peptide Hormone
3. Stimulates bone and muscle growth; raises blood glucose levels
Endorphins; source, type, and action? correct answers 1. Source = anterior pituitary.
2. Peptide hormone.
3. Action = Decrease sensation of pain; can promote euphoria.
prolactin; source, type, and action? correct answers 1. Source = anterior pituitary.
