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MCAT Biology > Nervous and Endocrine systems > Flashcards

Nervous and Endocrine systems Flashcards

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1
Q

What are the two broad components of the forebrain?

A
  • Telencephalon

- Diencephalon

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2
Q

True or false? The midbrain is part of the brainstem

A

true

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3
Q

What is the telencephalon?

A

The cerebral hemispheres (cerebrum), which contain an outer surface (cortex) of grey matter.

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4
Q

What is the diencephalon?

A
  • Thalamus
  • Hypothalamus
  • Pituitary gland
  • Limbic system (cerebellum, medula, basal ganglia etc.)
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5
Q

List the 12 cranial nerves and their functions

A
  • I olfactory nerve
  • II optic nerve
  • III oculomotor nerve (eye movement)
  • IV trochlear (eye movement)
  • V trigeminal (chewing and head sensory)
  • VI abducens (eye movement)
  • VII facial nerve (for taste)
  • VIII vestibulo-cochlear (equilibrium)
  • IX glosso-pharyngeal (taste and swollowing)
  • X vagus nerve (speech, swallowing, heart rate)
  • XI accessory nerve (head rotation and shoulder movement)
  • XII hypoglossal (tongue movement)
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6
Q

List the three meninges (from outer to inner)

A
  • dura mater
  • arachnoid mater
  • pia mater
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7
Q

What are effector receptors?

A

Every organ that can be stimulated by nerve impulses (eg. skeletal muscle)

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8
Q

Where does the sympathetic nervous system originate in the spinal cord?

A

Neurons located in the lateral horns of the grey matter

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9
Q

What nerves do parasympathetic nervous system fibers pass through?

A

Primarily the vagus nerves
- Others pass through other cranial nerves and the anterior roots of the sacral segments of the spinal cord.

parasympathetic fibres do not spread as extensively through the body as do sympathetic fibres. But they do innervate some of the thoracic and abdominal organs, as well as the pupillary sphincter and ciliary muscles. of the eye and the salivary glands.

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10
Q

Give the pathway of an autonomic impulse from the brain.

A
  • Cell body in brain/spinal cord
  • Axon projects outside of CNS to synapse with the cell body of a second neuron in an autonomic ganglion
  • The axon of the second neuron (postganglionic fibre) extends to a visceral effector
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11
Q

Why do parasympathetic postganglionic fibres relatively short compared to sympathetic fibres in the PNS?

A

parasympathetic ganglia are located near or within various visceral organs.

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12
Q

What do Golgi tendons and muscle spindles detect?

A

Golgi tendons: tension in tendons

Muscle spindles: muscle fibre stretching

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13
Q

Give the components of the outer, middle and inner ear

A

Outer

  • The pinna (cartilaginous, includes earlobe)
  • Auditory meatus (ear canal)

Middle

  • Tempanic membrane
  • Tympanic cavity
  • auditory ossicles (malleus, incus and stapes)
  • Oval window

Inner

  • 3 Semicircular canals
  • Cochlea
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14
Q

What is the eustachian tube?

A

A hollow tube that connects the middle ear (tympanic cavity) to the pharynx. It maintains equal pressure on both sides of the tympanic membrane.

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15
Q

How is the image that is formed on the retina orientated?

A

Inversely (upside down and reversed from left to right)

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16
Q

What is myopia?

A

(short sightedness/nearsighted). An image is formed in front of the retina because the lens converges light too much (long eyeballs).

A concave lens helps correct this

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17
Q

What is hyperopia?

A

Long-sightedness or farsighted.

An image is formed behind the retina, since the eyeballs are too short. A converging (convex) lens helps focus teh image on the retina

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18
Q

What is an astigmatism?

A

The curvatures of either the cornea or the lens are different at different angles. A cylindrical lens helps to correct this.

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19
Q

What is presbyopia?

A

Inability to focus vision, especially on objects that are close up. Seen commonly in elderly.

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20
Q

What are the three major ways in which hormones function?

A
  1. Controlling transport of substances through cell membranes
  2. Controlling activity of some of the specific genes, which in turn determine the formation of specific enzymes
  3. Controlling some metabolic systems of cells directly
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21
Q

Contrast steroid/non-steroid hormones.

A

These can diffuse across the plasma membrane and thus, they tend to have a direct intracellular effect.

Non-steroid hormones do not diffuse across the plasma membrane, they tend to bind plasma membrane receptors, which increase intracellular cyclic AMP concentration, which in turn brings about cellular changes, which are recognized as the hormone’s actions.

22
Q

List the pituitary hormones (8)

A

Anterior pituitary

  • Growth hormone (GH)
  • Thyroid stimulating hormone (TSH)
  • Adrenocorticotropic hormone (ACTH)
  • Prolactin
  • Follicle stimulating hormone (FSH)
  • Luteinizing hormone (LH)

Posterior pituitary

  • Vasopressin (ADH)
  • Oxytocin
23
Q

In what two ways does the hypothalamus effect the pituitary gland?

A
  1. Portal system, releasing factors in blood effect the anterior pituitary
  2. The hypothalamus contains neurosecretory cells that secrete their products (especially oxytocin and vasopressin) directly into the posterior pituitary, where they can be released to the rest of the body
24
Q

What does thyroid stimulating hormone do?

A

Stimulates the thyroid gland to produce:

  • thyroxine/T4
  • Triiodothyronine/T3

Which contain 4 and 3 iodine atoms, respectively. These increase the basal metabolic rate of the body (BMR).

25
Q

What does adrenocorticotropic hormone do?

A

Strongly stimulates the production of cortisol by the adrenal cortex, and stimulates the production of the other adrenocortical hormones (to a lesser extent)

26
Q

What does prolactin do?

A

Development of breasts during pregnancy and promotion of milk secretion after childbirth

27
Q

What does vasopressin (ADH) do?

A

Enhances the rate of water reabsorption from the renal tubules. ADH also constricts the arterioles and causes a rise in arterial blood pressure.

28
Q

What does oxytocin do?

A

Oxytocin causes contraction of the uterus and to a lesser extent the other smooth muscles of the body. It also stimulates the myoepithelial cells of the breast in a manner that makes the milk flow into the ducts. This is termed milk ejection, or milk let-down

29
Q

What are the three different steroid hormones secreted by the adrenal gland?

A
  • Mineralocorticoids (eg. aldosterone)
  • Glucocorticoids (eg. cortisol, cortisone)
  • Sex hormones (eg. androgens and estrogens)
30
Q

What are mineralocorticoids (eg. aldosterone)?

A

These influence the electrolyte balances of teh body.

Aldosterone promotes sodium retention and potassium excretion (through urine).

31
Q

What are glucocorticoids (eg. cortisol)?

A

Also called hydrocortisone. Glucocorticoids affect the metabolism of carbohydrates, proteins and lipids. Causes increase in blood concentration of glucose by decreasing the uptake of glucose into cells. It causes degradation of proteins and causes increased use of fate for energy.

32
Q

What is secreted from the adrenal medulla?

A

Epinephrine and norepinephrine

33
Q

What do thyroid glandular cells secrete? What controls the rate of synthesis?

A

Thyroglobulin thyroxine

TSH from the pituitary influences synthesis rate

34
Q

What do thyroid hormones do?

A
  • Increase synthesis rate of proteins in most cells

- Increase size and number of mitochondria to promote cellular metabolism

35
Q

What is hyperthyroidism?

A

Excess of thyroid secretion above that needed for normal function. Increased rate of metabolism throughout the body.

36
Q

What is hypothyroidism?

A

Inadequate amount of thyroid hormone secreted into the blood stream. Slows down the metabolic rate and enhances the collection of mucinous fluid in tissue spaces, creating edematous (fluid filled) state called myxedema

37
Q

How does the thyroid and parathyroid glands effect blood calcium concentration?

A
  • Thyroid produces calcitonin, which inhibits osteoclast activity and stimulates osteoblasts to form bone tissue; thus blood [Ca2+] decreases.
  • The parathyroid glands produce parathormone, which stimulates osteocasts to break down bone, thus raising Ca2+ and PO4 in the blood
38
Q

Describe pancreatic endocrine function

A

The pancreas contains clusters of cells (islets of Langerhans) closely associated with blood vessels. The islets of Langerhans contain alpha cells, which secrete glucagon and beta cells, which secrete insulin.

Glucagon increases blood glucose concentration by promoting the following events in the liver: the conversion of glycogen to glucose (glycogenolysis) and the production of glucose from amino acids (gluconeogenesis).

Insulin decreases blood glucose by increasing cellular uptake of glucose. A deficiency in insulin results in diabetes mellitus.

39
Q

What do alpha/beta cells of the pancreas secrete?

A

Alpha: Glucagon (promotes glucogenolysis and gluconeogenesis in the liver)

Beta: Insulin (increases cellular uptake of glucose)

40
Q

Describe the endocrine functions of the kidney

A
  • Produces renin (water resorption) and erythropoietin (increases production of erythrocytes in red bone marrow)
  • Helps activate vitamin D
41
Q

How must vitamin D be activated?

A

By hydroxylation in the liver and kidney

42
Q

Describe the activity of renin (secreted from kidney)

A

Increases water resorption and blood pressure through the activation of the Renin-Angiotensin system, which produces angiotensin II from angiotensin I.

Angiotensin II acts on the adrenal cortex to increase the synthesis and release of aldosterone, it also constricts blood vessels.

43
Q

Cholesterol is a precursor of which of the following hormones?

  1. Insulin
  2. Gastin
  3. Thyroxin
  4. Estrogen
A

Cholesterol is a precursor of steroid hormones, only estrogen is a steroid hormone in this list.

44
Q

What are the five groups of steroid hormones? What are these all derived from?

A
  • Glucocorticoids
  • Mineralocorticoids
  • Androgens
  • Estrogens
  • Progesterones

These groups are categorized according to the receptors they bind to (of the same name)

45
Q

Vasoconstriction of which vessels will most effectively reduce fat absorption from the small intestine into the bloodstream?

A

Lacteals inside intestinal villi of the small intestine

46
Q

Production of which of the following hormones will be inhibited by the administration of dietary calcium to prevent osteoporosis?

  1. Growth hormone
  2. Calcitonin
  3. Thyroid hormone
  4. Parathyroid hormone
A
  1. Parathyroid hormone

Parathyroid hormone is inhibited by high levels of calcium, it also stimulates resorption of bone through stimulation of osteoclasts.

A mnemonic to remember what calcitonin/parathyroid hormone does is:

Calcitonin-in, parathyroid-rid

47
Q

Osteoporosis is seen in women following estrogen withdrawal.

A man is treated with low doses of an estrogen analogue to destroy an estrogen-responsive adrenal tumor. Compared to an age-matched control (no estrogen treatment), this patient’s chances of developing osteoporosis will most likely be increased/decreased/the same?

A

Approximately the same. Men never had high levels of estrogen in the first place, so they do not experience withdrawal of it.

48
Q

Aldosterone is a mineralocorticoid steroid released from the adrenal gland. What does it do?

A

It causes sodium retention in the body and potassium excretion through urine.

It acts on distal tubules and collecting ducts of the kidneys. When sodium is retained, water is also reabsorbed. So aldosterone causes a rise in blood pressure through water retention.

49
Q

Would an increase in the level of plasma aldosterone be expected to follow ingestion of excessive quantities of NaCl?

A

No, aldosterone causes Na reabsorption by kidney tubules, decreasing Na concentration in the urine.

50
Q

The temporary increase in the sarcolemmal permeability to Na and K ions that occurs at the motor end plate of a neuromuscular junction is immediately preceded by what?

A

The release of acetylcholine from the motor neuron into the synaptic gap

51
Q

How does taking excess testosterone possibly render a man infertile?

A

Testosterone engages in a negative feedback loop with the hypothalamus.

Excess testosterone will reduce GnRF secretion from the hypothalamus, limiting the secretion of both FSH and LH.

Reduced FSH would inhibit Sertoli cells from promoting and maintaining spermatogenesis in the seminiferous tubules.

52
Q

Damage to what pair of nerves comprising the descending pathways, would likely cause persons with spinal cord damage to have no control over the micturition process?

A

Micturition = urination

Damage to the vagus nerve would likely cause this. The vagus nerve innervates smooth muscle of internal organs.

MCAT Biology (29 decks)

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