Neurons

Question 1

What is a neuron? What are the three main types of neurons?

Answer 1

Functional unit of nervous system. Motor neuron, sensory neuron, interneuron.

Question 2

What are the structures in a neuron and what are their functions?

Answer 2

Dendrite, Axon, Nodes of Ranvier, Myelin Sheath, Cell body, nucleus

Dendrite detects stimulus

Cell body - integration- converts stimulus to response

Axon conducts response

Synapse transmits response

NTs coordinate metabolic activities

Question 3

How does the action potential move along an axon without requiring another stimulus?

Answer 3

Saltatory conduction (jumping) = transmission of action potential along a myelinated axon. Jumping node over myelin.

Question 4

What is the reflex arc? Five parts to the reflex arc. Why is it faster than a neural response that requires voluntary action?

Answer 4

Reflex arc = involuntary response to stimulus (faster than adrenaline). Fast because they have few synapses to travel across.
5 parts
Receptor
Sensory neuron
Interneuron
Motor neuron
Effector

Question 5

What is a synapse? How do they work?

Answer 5

Synapse is the transmission site of electrical nerve impulses between 2 neurons.

Question 6

CNS - what is it composed of? What are the meninges?

Answer 6

Brain, spinal cord, optic nerve. Meninges = 3 layer membrane that surrounds CNS. Contains cerebrospinal fluid, which is a shock absorber & transports. Spinal cord has gray matter (unmyelinated interneurons) and white matter (myelinated motor neurons). Brain maintains homeostasis.

Question 7

Forebrain

Answer 7

Forebrain = largest, Thalamus = relays sensory information. Hypothalamus= important functions in the endocrine system, controls the pituitary. Cerebrum= largest part. 4 lobes = frontal, temporal, temporal, parietal, occipital. Control intellect, speech, memory.

Question 8

Midbrain

Answer 8

Midbrain= 4 spheres of gray matter, eyes + ears

Question 9

Hindbrain

Answer 9

Hindbrain- Behind midbrain. Cerebellum = unconscious. Medulla oblongata = heart & breathing rate. Pons= relays messages from cerebellum to medulla.

Question 10

PNS - what is it composed of, what are the two main divisions and their functions?

Answer 10

Somatic = voluntary control, sensory + motor
Autonomic= involuntary, adjust to external conditions. Controlled by hypothalamus/medulla oblongata.

Divided into 2 sections → sympathetic & parasympathetic. Sympathetic = fight or flight. Secretes Ach, norepinephrine. Raises heart rate. Parasympathetic= Returns body back to normal. Secretes Ach. Decrease heart rate.

Question 11

What are hormones? What are their characteristics (ie., how do they work). Protein vs. Steroid hormones.

Answer 11

Hormones = chemical messengers that send signals in the body. Secreted in small amounts, act slow but last long. Effect depends on receptors in the cell. Travel by blood. Steroid = fat soluble, Protein = water soluble.

Question 12

What is the master gland? Why is it called this? Where is it located? What is it connected to? How many hormones does it release?

Answer 12

Master gland = pituitary. Small gland attached to hypothalamus. 2 lobes (anterior & posterior).

Posterior is part of NS, doesn’t produce hormones. Nerves stimulate release of ADH and oxytocin.

Anterior releases 6 hormones: TSH (thyroid) ACTH, PRL, hGH, FSH (follicle stimulating) LH (luteinizing).
Anterior- series of blood vessels from hypothalamus → anterior to control release of hormones.

Question 13

Short term stress

Answer 13

Short term stress → NS
Hypothalamus detects stress, sympathetic NS activates adrenal
Adrenal glands activate adrenal medulla
Adrenal medulla secretes epinephrine to increase glucose release & norepinephrine which constrict blood vessels to increase heart rate & initiate fight or flight ** feedback loop

Question 14

Long term stress

Answer 14

Long term stress → Hormone response
Hypothalamus detects stress & target pituitary, secrete ACTH
ACTH travels in blood to adrenal glands.
Adrenal cortex is activated
Adrenal cortex secretes cortisol, saves glucose, and uses fats & proteins for fuel. Aldosterone increases Na, water absorption, blood pressure

Question 15

What is the parathyroid gland involved in monitoring?

Answer 15

Calcium. If it is too low in the blood, it secretes PTH. Bones release calcium, kidneys reabsorb it from urine. Activates vitamin D to stimulate absorption of calcium in blood to raise levels.

Question 16

What are the four phases to the menstrual cycle? What happens to the levels of estrogen, progesterone, LH and FSH in each of these cycles and what are the effects of these hormones?

Answer 16

Flow phase, follicular, ovulation, luteal. Levels = see graph. Flow → lining sheds. Follicular → follicle matures due to FSH. estrogen allows pituitary to release LH and triggers ovulation. Progesterone allows uterine line thickness. Ovulation → follicle ruptures, egg & corpus luteum produced. Luteal → LH allows corpus luteum to release progesterone and estrogen. increasing uterine lining, ready for implantation. FSH and LH production stops.

Question 17

What is the role of the corpus luteum?

Answer 17

It secretes progesterone, and degenerates if there is no pregnancy. Lowers progesterone and estrogen, raises FSH. Cycle repeats.

Question 18

Testosterone role

Answer 18

Promotes secondary sex characteristics, muscle development, facial hair, inhibit LH release

Question 19

How is urine formed?

Answer 19

Uric acid is created by purine digestion from nucleic acids. Enter blood. Liver rids body of toxins, soluble components enter blood. Protein metabolism creates ammonia (toxic). Reacts with NH3 to CO2 to urea, enters blood. Kidney accepts and filters blood containing uric acid, and products from liver. Waste forms, enters ureters, bladder, urethra, exits body.

Question 20

When is glucagon vs insulin used

Answer 20

Glucagon - blood glucose too low
Insulin- blood glucose too high